• ot optics question for Phil

    From John Larkin@21:1/5 to All on Thu Aug 11 16:38:38 2022
    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?



    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From a a@21:1/5 to John Larkin on Thu Aug 11 17:57:38 2022
    On Friday, 12 August 2022 at 02:46:38 UTC+2, John Larkin wrote:
    On Thu, 11 Aug 2022 17:32:40 -0700 (PDT), a a <mant...@gmail.com>
    wrote:
    On Friday, 12 August 2022 at 01:38:57 UTC+2, John Larkin wrote:
    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?



    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
    Optical Diopter Strength Explained

    https://focusers.com/pages/explanation-of-diopter-strength
    Thanks, but that doesn't answer my question.
    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
    https://wiki.endmyopia.org/wiki/Diopters

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From a a@21:1/5 to John Larkin on Thu Aug 11 17:32:40 2022
    On Friday, 12 August 2022 at 01:38:57 UTC+2, John Larkin wrote:
    What's a good way to measure the negative diopter of my glasses, given minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?



    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
    Optical Diopter Strength Explained

    https://focusers.com/pages/explanation-of-diopter-strength

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to All on Thu Aug 11 17:46:22 2022
    On Thu, 11 Aug 2022 17:32:40 -0700 (PDT), a a <manta103g@gmail.com>
    wrote:

    On Friday, 12 August 2022 at 01:38:57 UTC+2, John Larkin wrote:
    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?



    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason" >Optical Diopter Strength Explained

    https://focusers.com/pages/explanation-of-diopter-strength

    Thanks, but that doesn't answer my question.

    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to jjlarkin@highlandtechnology.com on Thu Aug 11 18:09:36 2022
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are over-correcting.

    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cydrome Leader@21:1/5 to John Larkin on Fri Aug 12 04:40:54 2022
    John Larkin <jjlarkin@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Next question is where the hell did you get those glasses in the first
    place, if you have no idea of what their prescription even is?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to presence@MUNGEpanix.com on Thu Aug 11 22:02:18 2022
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >lense" and then concluding a focal length of -11 inches.

    That conversion is not difficult.


    Next question is where the hell did you get those glasses in the first
    place, if you have no idea of what their prescription even is?

    I don't have the prescription handy. And I like to measure things.

    I think my eye has changed since I got the glasses.

    Are you always so rude?



    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Joe Gwinn@21:1/5 to presence@MUNGEpanix.com on Fri Aug 12 09:25:59 2022
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.

    This well predates NASA, having been developed by Isaac Newton in the
    16th century:

    .<https://en.wikipedia.org/wiki/Opticks>


    Diopters are the inverse of the focal length in meters. Yes, a lens
    can have negative power expressed in diopters:

    .<https://en.wikipedia.org/wiki/Thin_lens>


    Joe Gwinn

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Fri Aug 12 12:51:30 2022
    John Larkin wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are over-correcting.

    You'll get a better measurement by making the aperture much smaller than
    the focal length. (The magnitude of the FL, that is.)

    An object at a distance d_o from the center of a thin lens of focal
    length f produces an image at a distance d_i, where

    1/d_o + 1/d_i = 1/f.

    The sun is very distant, so we can ignore 1/d_0, so that the image of
    the sun is at f, which for a concave lens is on the side towards the sun.

    You figure the FL using similar triangles as usual, except
    backwards--given two projections, find the focal point. That takes one
    more line of algebra.

    The sun 's angular subtense is about 0.5 degrees, so you have to take
    that contribution out somehow--if you measure the disk diameter out to
    where the intensity falls to nearly zero, your measured angle will be
    0.5 degrees too large, and your measured FL correspondingly too short.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to presence@MUNGEpanix.com on Fri Aug 12 11:43:08 2022
    On Fri, 12 Aug 2022 18:24:25 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    Joe Gwinn <joegwinn@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>>>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>>the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a >>>> screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >>>lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.

    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    I have no issue with inch focal lengths by themselves. Tons of "standard" >sizes in mm for objective lenses are based off the original ones in
    inches.


    Glasses are prescribed in diopters. I measured the focal length of
    that lens as -11 inches. That's about -3.5 diopters.

    Is that weird?

    --

    John Larkin Highland Technology, Inc trk

    The cork popped merrily, and Lord Peter rose to his feet.
    "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cydrome Leader@21:1/5 to Joe Gwinn on Fri Aug 12 18:24:25 2022
    Joe Gwinn <joegwinn@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >>lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.

    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    I have no issue with inch focal lengths by themselves. Tons of "standard"
    sizes in mm for objective lenses are based off the original ones in
    inches.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Cydrome Leader on Fri Aug 12 14:37:08 2022
    Cydrome Leader wrote:
    Joe Gwinn <joegwinn@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>>> minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>> the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a >>>> screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.

    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    I have no issue with inch focal lengths by themselves. Tons of "standard" sizes in mm for objective lenses are based off the original ones in
    inches.



    Eyeglasses prescriptions are in dioptres.

    Don't worry, CD, JL is very unlikely to crash into Mars this week. ;)

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cydrome Leader@21:1/5 to Phil Hobbs on Fri Aug 12 19:33:28 2022
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
    Cydrome Leader wrote:
    Joe Gwinn <joegwinn@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>>>> minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>>> the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a >>>>> screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >>>> lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.

    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    I have no issue with inch focal lengths by themselves. Tons of "standard"
    sizes in mm for objective lenses are based off the original ones in
    inches.



    Eyeglasses prescriptions are in dioptres.

    He doesn't know his rx, or that of the glasses. It's all pointless.

    Don't worry, CD, JL is very unlikely to crash into Mars this week. ;)

    Ha.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Cydrome Leader on Fri Aug 12 16:12:02 2022
    Cydrome Leader wrote:
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
    Cydrome Leader wrote:
    Joe Gwinn <joegwinn@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    John Larkin <jjlarkin@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjlarkin@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>>>>> minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>>>> the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a >>>>>> screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >>>>> lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.

    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    I have no issue with inch focal lengths by themselves. Tons of "standard" >>> sizes in mm for objective lenses are based off the original ones in
    inches.



    Eyeglasses prescriptions are in dioptres.

    He doesn't know his rx, or that of the glasses. It's all pointless.

    If the resting focus of that eye is +2.3 dioptre (17 inch FL), then a
    -3.6 dioptre corrective is indeed too strong. (This is after cataract
    surgery, so there's no accommodation to take into account.)

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Walliker@21:1/5 to Cydrome Leader on Sun Aug 14 15:12:04 2022
    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote:
    Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a >>> screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >>lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked
    in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    I have no issue with inch focal lengths by themselves. Tons of "standard" sizes in mm for objective lenses are based off the original ones in
    inches.

    John

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to jrwalliker@gmail.com on Sun Aug 14 18:32:12 2022
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote:
    Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >> >>>>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a >> >>> screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked
    in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cydrome Leader@21:1/5 to jlarkin@highlandsniptechnology.com on Mon Aug 15 18:26:44 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote:
    Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>> >>>>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>> >>>>the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a >>> >>> screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >>> >>lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    Well, the diopter is just the reciprocal of the focal length in metres, so >>it is relevant. Opticians use diopters because lenses can be stacked
    in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to presence@MUNGEpanix.com on Mon Aug 15 19:18:28 2022
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote:
    Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given >>>> >>>>minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>> >>>>the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a >>>> >>> screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>> >>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >>>> >>lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    Well, the diopter is just the reciprocal of the focal length in metres, so >>>it is relevant. Opticians use diopters because lenses can be stacked
    in front of each other and the powers in diopters simply add or subtract >>>as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cydrome Leader@21:1/5 to jlarkin@highlandsniptechnology.com on Tue Aug 16 21:06:12 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote:
    Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>> >>>>the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>> >>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a >>>>> >>lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so >>>>it is relevant. Opticians use diopters because lenses can be stacked >>>>in front of each other and the powers in diopters simply add or subtract >>>>as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator
    where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance,
    in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Cydrome Leader on Tue Aug 16 23:55:05 2022
    On 2022-08-16 23:06, Cydrome Leader wrote:
    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote:
    Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>>>>>>> the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>>>>>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >>>>> in front of each other and the powers in diopters simply add or subtract >>>>> as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance,
    in siemens of course? Maybe it's time to hawk special "ultra high susceptance" cables to the audiophiles.


    Conductance, susceptance, admittance, they have their uses. In the
    design of matching networks, filters and pulse forming networks, it's
    common to switch back and forth between those and their reciprocals
    all the time.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to presence@MUNGEpanix.com on Tue Aug 16 15:26:18 2022
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote:
    Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on >>>>>> >>>>the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>>> >>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so >>>>>it is relevant. Opticians use diopters because lenses can be stacked >>>>>in front of each other and the powers in diopters simply add or subtract >>>>>as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator >where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance,
    in siemens of course? Maybe it's time to hawk special "ultra high >susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot
    like a classic HP calculator. Very nice.

    Are kids learning RPN these days?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cydrome Leader@21:1/5 to Jeroen Belleman on Wed Aug 17 04:06:55 2022
    Jeroen Belleman <jeroen@nospam.please> wrote:
    On 2022-08-16 23:06, Cydrome Leader wrote:
    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>>>>>>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >>>>>> in front of each other and the powers in diopters simply add or subtract >>>>>> as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator
    where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance,
    in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.


    Conductance, susceptance, admittance, they have their uses. In the
    design of matching networks, filters and pulse forming networks, it's
    common to switch back and forth between those and their reciprocals
    all the time.

    Jeroen Belleman

    Do you have an example? I'm just curious. Say you're making a 2 stage type
    E network, where do the weird units come into play?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cydrome Leader@21:1/5 to John Larkin on Wed Aug 17 04:12:52 2022
    John Larkin <jlarkin@highland_atwork_technology.com> wrote:
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>>>> >>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >>>>>>in front of each other and the powers in diopters simply add or subtract >>>>>>as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over >>calculations.

    There really is no going back once you learn RPN. Even a fancy calculator >>where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance, >>in siemens of course? Maybe it's time to hawk special "ultra high >>susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot
    like a classic HP calculator. Very nice.

    Are kids learning RPN these days?

    Not directly. They push python as a programming language, and it's real backwards, but no official RPN classes anywhere. TI still runs the
    cartel for school approved graphing calculators.

    I'm not even sure what they teach these days that offers any real value
    outside of constantly taking tests ina school, and learning how to be meek
    and offended by everything.

    Was chatting with a machinist who say they regularly have people apply for assembly jobs at the factory and can't even use a socket wrench. They pass
    on those folks. People are so helpless fewer and fewer cars even come with
    a spare, as they know the driver won't be able to change it in the first
    place. Sad times.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to presence@MUNGEpanix.com on Tue Aug 16 21:49:47 2022
    On Wed, 17 Aug 2022 04:12:52 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    John Larkin <jlarkin@highland_atwork_technology.com> wrote:
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>>>>> >>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >>>>>>>in front of each other and the powers in diopters simply add or subtract >>>>>>>as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over >>>calculations.

    There really is no going back once you learn RPN. Even a fancy calculator >>>where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance, >>>in siemens of course? Maybe it's time to hawk special "ultra high >>>susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot
    like a classic HP calculator. Very nice.

    Are kids learning RPN these days?

    Not directly. They push python as a programming language, and it's real >backwards, but no official RPN classes anywhere. TI still runs the
    cartel for school approved graphing calculators.

    I'm not even sure what they teach these days that offers any real value >outside of constantly taking tests ina school, and learning how to be meek >and offended by everything.

    Was chatting with a machinist who say they regularly have people apply for >assembly jobs at the factory and can't even use a socket wrench. They pass
    on those folks. People are so helpless fewer and fewer cars even come with
    a spare, as they know the driver won't be able to change it in the first >place. Sad times.

    I have a relative who has a PhD in Engineering Mechanics. He is hugely
    offended if anyone calls him a mechanical engineer. He's helpless at
    fixing things.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Cydrome Leader on Wed Aug 17 10:36:50 2022
    On 2022-08-17 06:06, Cydrome Leader wrote:
    Jeroen Belleman <jeroen@nospam.please> wrote:
    On 2022-08-16 23:06, Cydrome Leader wrote:
    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>>>>>>>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >>>>>>> in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator >>> where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance, >>> in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.


    Conductance, susceptance, admittance, they have their uses. In the
    design of matching networks, filters and pulse forming networks, it's
    common to switch back and forth between those and their reciprocals
    all the time.

    Jeroen Belleman

    Do you have an example? I'm just curious. Say you're making a 2 stage type
    E network, where do the weird units come into play?


    The typical case is the development of a complex impedance into a ladder network. A continuous fraction expansion has alternating impedance and admittance expressions as you descend into the denominator. Look up
    writings by Wilhelm Cauer, Sid Darlington, Ernst Guillemin and Ronald
    Foster, among many others.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Jeroen Belleman on Thu Aug 18 13:04:14 2022
    On 8/16/22 5:55 PM, Jeroen Belleman wrote:
    On 2022-08-16 23:06, Cydrome Leader wrote:
    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my
    glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged >>>>>>>>>>> circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens


    My lens is 2" wide and sunlight projects a 4" wide image at >>>>>>>>>> 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses >>>>>>>>>> are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the
    diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>>> either known or unknowns in what he's trying to calculate or
    confirm.

    Well, the diopter is just the reciprocal of the focal length in
    metres, so
    it is relevant.  Opticians use diopters because lenses can be stacked >>>>>> in front of each other and the powers in diopters simply add or
    subtract
    as appropriate.  This is much easier than working directly with
    focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator
    where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance,
    in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.


    Conductance, susceptance, admittance, they have their uses. In the
    design of matching networks, filters and pulse forming networks, it's
    common to switch back and forth between those and their reciprocals
    all the time.

    Jeroen Belleman


    Right, which is why most Smith chart pads have both impedance and
    admittance graticules.

    I use admittance all the time in doing mental arithmetic for circuit design.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    https://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Thu Aug 18 13:23:57 2022
    On 8/17/22 12:49 AM, jlarkin@highlandsniptechnology.com wrote:
    On Wed, 17 Aug 2022 04:12:52 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    John Larkin <jlarkin@highland_atwork_technology.com> wrote:
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <presence@MUNGEpanix.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>>>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are >>>>>>>>>>>> over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >>>>>>>> in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator >>>> where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance, >>>> in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot
    like a classic HP calculator. Very nice.

    Are kids learning RPN these days?

    Not directly. They push python as a programming language, and it's real
    backwards, but no official RPN classes anywhere. TI still runs the
    cartel for school approved graphing calculators.

    I'm not even sure what they teach these days that offers any real value
    outside of constantly taking tests ina school, and learning how to be meek >> and offended by everything.

    Was chatting with a machinist who say they regularly have people apply for >> assembly jobs at the factory and can't even use a socket wrench. They pass >> on those folks. People are so helpless fewer and fewer cars even come with >> a spare, as they know the driver won't be able to change it in the first
    place. Sad times.

    I have a relative who has a PhD in Engineering Mechanics. He is hugely offended if anyone calls him a mechanical engineer. He's helpless at
    fixing things.


    Bet he's not as useless as a guy I used to know who has a PhD in
    "Industrial Engineering".

    What is "industrial engineering", anyway? AFAICT it seems to be a
    dumping ground for people who wash out of ME or EE.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    https://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Thu Aug 18 11:41:26 2022
    onsdag den 17. august 2022 kl. 06.12.59 UTC+2 skrev Cydrome Leader:
    John Larkin <jlarkin@highland_atwork_technology.com> wrote:
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwal...@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >>>>>>> either known or unknowns in what he's trying to calculate or confirm. >>>>>>>
    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >>>>>>in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over >>calculations.

    There really is no going back once you learn RPN. Even a fancy calculator >>where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance, >>in siemens of course? Maybe it's time to hawk special "ultra high >>susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot
    like a classic HP calculator. Very nice.

    Are kids learning RPN these days?
    Not directly. They push python as a programming language, and it's real backwards, but no official RPN classes anywhere. TI still runs the
    cartel for school approved graphing calculators.

    I'm not even sure what they teach these days that offers any real value outside of constantly taking tests ina school, and learning how to be meek and offended by everything.

    Was chatting with a machinist who say they regularly have people apply for assembly jobs at the factory and can't even use a socket wrench. They pass
    on those folks. People are so helpless fewer and fewer cars even come with
    a spare, as they know the driver won't be able to change it in the first place. Sad times.

    they did the math, a spare is used so rarely that it is a waste of space and fuel to carry one around

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cydrome Leader@21:1/5 to Lasse Langwadt Christensen on Mon Oct 3 20:37:09 2022
    Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:
    onsdag den 17. august 2022 kl. 06.12.59 UTC+2 skrev Cydrome Leader:
    John Larkin <jlarkin@highland_atwork_technology.com> wrote:
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwal...@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote:
    Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of >> >>>>>>> either known or unknowns in what he's trying to calculate or confirm.

    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >> >>>>>>in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator >> >>where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance, >> >>in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot
    like a classic HP calculator. Very nice.

    Are kids learning RPN these days?
    Not directly. They push python as a programming language, and it's real
    backwards, but no official RPN classes anywhere. TI still runs the
    cartel for school approved graphing calculators.

    I'm not even sure what they teach these days that offers any real value
    outside of constantly taking tests ina school, and learning how to be meek >> and offended by everything.

    Was chatting with a machinist who say they regularly have people apply for >> assembly jobs at the factory and can't even use a socket wrench. They pass >> on those folks. People are so helpless fewer and fewer cars even come with >> a spare, as they know the driver won't be able to change it in the first
    place. Sad times.

    they did the math, a spare is used so rarely that it is a waste of space and fuel to carry one around

    Who did the math? Airbgs and seatbelts seem like a waste too by the same
    MBA logic.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Mon Oct 3 13:43:53 2022
    mandag den 3. oktober 2022 kl. 22.37.16 UTC+2 skrev Cydrome Leader:
    Lasse Langwadt Christensen <lang...@fonz.dk> wrote:
    onsdag den 17. august 2022 kl. 06.12.59 UTC+2 skrev Cydrome Leader:
    John Larkin <jlarkin@highland_atwork_technology.com> wrote:
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwal...@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >> >>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >> >>>>>>in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator
    where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance,
    in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot >> > like a classic HP calculator. Very nice.

    Are kids learning RPN these days?
    Not directly. They push python as a programming language, and it's real
    backwards, but no official RPN classes anywhere. TI still runs the
    cartel for school approved graphing calculators.

    I'm not even sure what they teach these days that offers any real value
    outside of constantly taking tests ina school, and learning how to be meek >> and offended by everything.

    Was chatting with a machinist who say they regularly have people apply for >> assembly jobs at the factory and can't even use a socket wrench. They pass >> on those folks. People are so helpless fewer and fewer cars even come with >> a spare, as they know the driver won't be able to change it in the first >> place. Sad times.

    they did the math, a spare is used so rarely that it is a waste of space and
    fuel to carry one around
    Who did the math? Airbgs and seatbelts seem like a waste too by the same
    MBA logic.

    you can't be silly enough to think that is the same....

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to presence@MUNGEpanix.com on Mon Oct 3 16:32:40 2022
    On Mon, 3 Oct 2022 20:37:09 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:
    onsdag den 17. august 2022 kl. 06.12.59 UTC+2 skrev Cydrome Leader:
    John Larkin <jlarkin@highland_atwork_technology.com> wrote:
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwal...@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>> >>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked >>> >>>>>>in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator >>> >>where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance, >>> >>in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot >>> > like a classic HP calculator. Very nice.

    Are kids learning RPN these days?
    Not directly. They push python as a programming language, and it's real
    backwards, but no official RPN classes anywhere. TI still runs the
    cartel for school approved graphing calculators.

    I'm not even sure what they teach these days that offers any real value
    outside of constantly taking tests ina school, and learning how to be meek >>> and offended by everything.

    Was chatting with a machinist who say they regularly have people apply for >>> assembly jobs at the factory and can't even use a socket wrench. They pass >>> on those folks. People are so helpless fewer and fewer cars even come with >>> a spare, as they know the driver won't be able to change it in the first >>> place. Sad times.

    they did the math, a spare is used so rarely that it is a waste of space and >> fuel to carry one around

    Who did the math? Airbgs and seatbelts seem like a waste too by the same
    MBA logic.


    If you read old books, up to 1960s maybe, "punctures" were very
    common. Nowadays tires rarely go flat, or even lose much air.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Walliker@21:1/5 to John Larkin on Tue Oct 4 02:26:08 2022
    On Tuesday, 4 October 2022 at 00:32:51 UTC+1, John Larkin wrote:
    On Mon, 3 Oct 2022 20:37:09 -0000 (UTC), Cydrome Leader <pres...@MUNGEpanix.com> wrote:

    Lasse Langwadt Christensen <lang...@fonz.dk> wrote:
    onsdag den 17. august 2022 kl. 06.12.59 UTC+2 skrev Cydrome Leader:
    John Larkin <jlarkin@highland_atwork_technology.com> wrote:
    On Tue, 16 Aug 2022 21:06:12 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 15 Aug 2022 18:26:44 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Sun, 14 Aug 2022 15:12:04 -0700 (PDT), John Walliker
    <jrwal...@gmail.com> wrote:

    On Friday, 12 August 2022 at 19:24:32 UTC+1, Cydrome Leader wrote: >>> >>>>>>> Joe Gwinn <joeg...@comcast.net> wrote:
    On Fri, 12 Aug 2022 04:40:54 -0000 (UTC), Cydrome Leader
    <pres...@MUNGEpanix.com> wrote:

    John Larkin <jjla...@highlandtechnology.com> wrote:
    On Thu, 11 Aug 2022 16:38:38 -0700, John Larkin
    <jjla...@highlandtechnology.com> wrote:


    What's a good way to measure the negative diopter of my glasses, given
    minimal tools up the the cabin?

    I can let the sun shine through a lens and see an enlarged circle on
    the ground a few feet away. What's the math on that?

    I found it online.

    https://physics.stackexchange.com/questions/566207/how-to-measure-the-strength-of-a-prescription-eyeglass-lens

    My lens is 2" wide and sunlight projects a 4" wide image at 11" from a
    screen. So the fl of the lens is -11".

    That's bad, since that eye focuses at about 17". These glasses are
    over-correcting.

    You're pulling some weird NASA moves by asking "what's the diopter of a
    lense" and then concluding a focal length of -11 inches.

    Nothing weird here. Just some simple optics.
    It is weird. He's going on about diopters, but they're not a part of
    either known or unknowns in what he's trying to calculate or confirm.

    Well, the diopter is just the reciprocal of the focal length in metres, so
    it is relevant. Opticians use diopters because lenses can be stacked
    in front of each other and the powers in diopters simply add or subtract
    as appropriate. This is much easier than working directly with focal lengths.

    It's just like resistors in parallel.

    When is the last time you use mhos in a calcuation?

    I type

    rval
    1/x

    (RPN) often. I don't call them mhos; they are actually Siemens.


    What resistor do you put across 5 ohms to get 3 ohms?

    3
    1/x
    5
    1/x
    -
    1/x


    Seems like the answer is never. I see lots of repetetive 1 over
    calculations.

    There really is no going back once you learn RPN. Even a fancy calculator
    where you can see rows of nested braces just doesn't compare.

    I always though mhos were just odd. So when did you last use susceptance,
    in siemens of course? Maybe it's time to hawk special "ultra high
    susceptance" cables to the audiophiles.

    I have an app on my Android phone, Free42, which looks and feels a lot >>> > like a classic HP calculator. Very nice.

    Are kids learning RPN these days?
    Not directly. They push python as a programming language, and it's real >>> backwards, but no official RPN classes anywhere. TI still runs the
    cartel for school approved graphing calculators.

    I'm not even sure what they teach these days that offers any real value >>> outside of constantly taking tests ina school, and learning how to be meek
    and offended by everything.

    Was chatting with a machinist who say they regularly have people apply for
    assembly jobs at the factory and can't even use a socket wrench. They pass
    on those folks. People are so helpless fewer and fewer cars even come with
    a spare, as they know the driver won't be able to change it in the first >>> place. Sad times.

    they did the math, a spare is used so rarely that it is a waste of space and
    fuel to carry one around

    Who did the math? Airbgs and seatbelts seem like a waste too by the same >MBA logic.

    If you read old books, up to 1960s maybe, "punctures" were very
    common. Nowadays tires rarely go flat, or even lose much air.

    I have changed wheels a few times over the last decade. The causes of punctures were horseshoe nails, fencing nails, woodscrews and in one case
    a damaged cast iron drain cover.

    I do drive a lot on country roads adjacent to stables and horse breeders.

    John

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Martin Brown@21:1/5 to John Larkin on Tue Oct 4 10:54:07 2022
    On 04/10/2022 00:32, John Larkin wrote:
    On Mon, 3 Oct 2022 20:37:09 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:

    Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:
    onsdag den 17. august 2022 kl. 06.12.59 UTC+2 skrev Cydrome Leader:

    Was chatting with a machinist who say they regularly have people apply for >>>> assembly jobs at the factory and can't even use a socket wrench. They pass >>>> on those folks. People are so helpless fewer and fewer cars even come with >>>> a spare, as they know the driver won't be able to change it in the first >>>> place. Sad times.

    they did the math, a spare is used so rarely that it is a waste of space and
    fuel to carry one around

    Who did the math? Airbgs and seatbelts seem like a waste too by the same
    MBA logic.

    If you read old books, up to 1960s maybe, "punctures" were very
    common. Nowadays tires rarely go flat, or even lose much air.

    Rubber chemistry and tyre manufacture has improved a lot in that time.

    The other snag is that modern cars push tyres hard enough that they have
    a spin handedness so your choice it limited to carrying a generic thin
    space saving spare or runflats. The latter leaves more room in the boot.

    Some of us are on run flats which are hellishly expensive but very
    impressive if you really do have a blowout at motorway speeds. Driver
    action required is pretty much limited to continue to steer, slow down
    and pull over to take a look at the damage. You can limp home at 50mph
    for up to 50 miles on a flat run flat tyre. Although I was inclined to
    give it a break every 15 minutes or so since it runs very hot.

    Doing 50mph on the inside lane of a UK motorway is pretty scary with
    HGVs on their limiters at 56mph overtaking at the last possible moment.

    I have had about half a dozen flat tyres and two of them were motorway
    blowouts after hitting coach bolts/sharp metal shards on the road. One
    went right through the outside tyre wall the other did invisible damage
    to inside tyre wall - only visible once it was up on a ramp. The run
    flat experience was much more user friendly than the classic tyre.

    --
    Regards,
    Martin Brown

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    * Origin: fsxNet Usenet Gateway (21:1/5)