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  1. #1
    Mustafa Umut Sarac's Avatar
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    Correspondance with lens design software maker

    I am an old user of summitar , elmar and summicron lenses.

    I was believing each lens have different qualities.

    After taking a mail from lens design software maker - for the last 40 years - ,
    I think i m wrong.

    He says that he is not believing leitz or other lenses have different qualities .
    He says you can make a lens blur free but not skin color expert.
    It was only about coatings and films ... not lenses.

    Is there anyone who changes his lens coating or what about coat the eyewear glasses with these coatings ?

    Best ,

    Mustafa Umut Sarac

  2. #2
    Ole
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    Mustafa, maybe you should have asked a lens design software user instead of a software maker?

    For what it's worth, my eyeglasses are coated. Many of my lenses are not, but some are. The colour rendition seems very similar across all my lenses, with the exception of the slightly yellowish Apo-Lanthar. But the skin rendition varies a lot - "blur free" isn't always best for skin tones!
    -- Ole Tjugen, Luddite Elitist
    Norway

  3. #3

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    Linos, who own Rodenstock, do sell glasses for vision, and handle special optical coatings. Zeiss also have a similar service. The refractive index, and other properties of glass (for lenses) does have an impact on the performance of the lens. It is generally understood that fewer optical elements in a lens can require a higher degree of assembly precision, while having many optical elements can allow for more corrections or wider tolerance during assembly (this is not always true, but a safe assumption).

    So while lens designs could be very straight forward to create, there are issues still with glass selection and manufacturing tolerances. Then you might consider coatings, or other aspects. Simply knowing the construction of a Summicron is quite a way from actually making your own.

    Some lenses are known from their performance at different camera to subject distances, or because of their aberrations. An excellent example of this is the old Nikon 105mm f2.5 AIS. That lens does not have a very favorable MTF at infinity, yet at closer distances wide open gives a very nice defocus rendition to backgrounds, and gives n in-focus rendition that many photographers have found to their liking. This lens was largely designed prior to heavy reliance on computers, and was simply an evolution of early designs. That Nikon got it right, and continued to sell this lens for decades, goes beyond what design specifications might indicate . . . in other words, things are seldom as simple as they might seem.

    Ciao!

    Gordon Moat Photography

  4. #4
    Mustafa Umut Sarac's Avatar
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    There are interesting papers on rendering at microsoft research and one of the paper relates radiance , it is highly technical but it adds shadows to the surface. I think it gives high quality bw picture effect.

    Software engineer says , I have to start interest with rendering.

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    the most variable and imprecise part of the colour equation will be and has always been the film and film processing. Assuming that film gives perfect colour rendition is a big mistake. Given that film will not give perfect colour rendition, then the very small differences in lense colour rendition makes it not worth worrying about for the vast majority of photographic purposes because the film colour rendition error will be far more significant. IMO

  6. #6
    Mustafa Umut Sarac's Avatar
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    There is a zeiss shop in istanbul which can paint the eyeglass to a given color ! There is ultra small , tiffany blue , historic glasses at them.
    I saw similar glasses at Ivan the terrible , lavonian ambassador from Eisenstein.
    And there are huge selection of hunting , golfing , driving glasses for to adapt better to rainy day or fogy day . I think i have a guide about weather , light and the color selection for a eyeglass.
    I think colormatic glasses also gives strange colors.
    I think this is a funny side , real time color vision.

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    The lens has to be designed to provide a flat focus plain, and have even brightness across the film, and also have all the colors ( a range of wave lengths ) focused in the same plane and point. It's not possible with out some trade offs. The cheap lenses have a lot more trade offs than the costly lenses. Most lenses even the old brass lesses have more three or more elements with elements is made from different glasses. The different glasses used in the lens assemble for color correction.
    It's not the camera......

  8. #8

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    i would love to look at the world through rose colored lenses


    interesting topic mustafa

    --john
    im empty, good luck

  9. #9
    Mustafa Umut Sarac's Avatar
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    John , I think you are interesting with laser glasses .
    Best rose colored glasses comes from neodymium additive.
    Lawrence Livermore order door size 2000 slabs from this material.
    They use it for amp the bright flash to laser light.
    Some glass additives make nonlinear filters , i think amp the light with nonlinear glass is very interesting.
    And I am interesting in to make my glass in small electric kiln from this material plus borax.

  10. #10
    Mustafa Umut Sarac's Avatar
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    Attention , i learned that borax is dangerous material for to melt in kiln , it can explode because it is never very dry.

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