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  1. #1

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    DIY lens- periscope question

    Hi

    I have a simple question. I've got two +1 lenses and I'd like to make periscope type lens +2 diopters.
    It is quite simple, just two parallel lenses, but what should be distance between them?

    greetings

    JW

  2. #2
    Maris's Avatar
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    I'm not sure it is possible to get a +2 lens out of two +1 lenses except by putting the lenses in contact. Gullstrand's Equation seems to apply here.
    Photography, the word itself, invented and defined by its author Sir John.F.W.Herschel, 14 March 1839 at the Royal Society, Somerset House, London. Quote "...Photography or the application of the Chemical rays of light to the purpose of pictorial representation,..". unquote.

  3. #3

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    Click image for larger version. 

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    This is periscope type lens. In my case both lenses are +1 diopters. as a whole, this couple has +2 diopters. My question is about distance between these tho lenses.

  4. #4
    Jim Jones's Avatar
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  5. #5

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    And you can model it with OpticalRayTracer.jar , a GPL download and very simple to use.

  6. #6
    Steve Smith's Avatar
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    Does it need to be exactly +2 Dioptres? Put them as close together as you can and I'm sure it will be accurate enough.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  7. #7

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    Thanks a lot. This is what I really needed :-))

    greetings

    JW

  8. #8
    Jim Jones's Avatar
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    Sometimes the answer to a simple question is more complicated than the answer to a complicated question. Is the focal length of the proposed Periscope critical? As you can see from Gullstrand's Equation the focal length will be slightly less than 500 mm for practical element separation. Will a shutter be used between the elements? What is the required image size? Periscopes have been designed to cover up to 70 degrees at f/30. In primitive cameras, the coverage was less, and the aperture larger. Will the chromatic aberration inherent in the Periscope be a problem? For black & white photography, performance can be improved by color filters. How will you mount the lenses? Some of us are experienced in improvising lenses and lens accessories.

  9. #9
    Mustafa Umut Sarac's Avatar
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    APUG is blind to optical science IMHO. For such forums , these questions are complex , some other forums , they are very easy to answer , nobody bothers. I could not find a sweet spot either.

  10. #10

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    Quote Originally Posted by Jim Jones View Post
    Sometimes the answer to a simple question is more complicated than the answer to a complicated question. Is the focal length of the proposed Periscope critical? As you can see from Gullstrand's Equation the focal length will be slightly less than 500 mm for practical element separation. Will a shutter be used between the elements? What is the required image size? Periscopes have been designed to cover up to 70 degrees at f/30. In primitive cameras, the coverage was less, and the aperture larger. Will the chromatic aberration inherent in the Periscope be a problem? For black & white photography, performance can be improved by color filters. How will you mount the lenses? Some of us are experienced in improvising lenses and lens accessories.
    The focal length is not critical. 500mm +/- 10mm is no problem. There is no shutter inside. Just simple couple of lenses and removable stops inside. The image size is 35x35cm. My periscope lens is done yet. I'l try it when the camera will be ready to use. My LFC camera is DIY as well.


    thanks a lot

    JW

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