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Thread: Chamonix Fresnel

  1. #11
    Forever Beardless Ari's Avatar
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    Re: Chamonix Fresnel

    Quote Originally Posted by rknewcomb View Post
    A somewhat related question...
    2) If most any groundglass is used with a fresnel on the OUTside, does it keep the focus point the same so the image is focused properly on the film?
    thanks!
    Robert
    Manufacturers vary in their use of the fresnel in front of, or behind, the GG.
    If you're in doubt, best to contact the manufacturer to see what's what, or post the question here for your specific camera make and model.

    So switching the fresnel to the front when it should be behind might cause focusing errors.

  2. #12

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    Re: Chamonix Fresnel

    Quote Originally Posted by rknewcomb View Post
    1) Does a Yanke GG/fresnel change the point of focus such that it creates an error between the focus on the glass and what you get on the film?
    2) If most any groundglass is used with a fresnel on the OUTside, does it keep the focus point the same so the image is focused properly on the film?
    Quote Originally Posted by Ari View Post
    No; it is one piece, with a plain acrylic overlay.
    Pretty hard to screw up, much like the superior Wista screen.
    And similar to the Canham Fresnel but the Canham uses a glass protective cover.

  3. #13

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    Re: Chamonix Fresnel

    Quote Originally Posted by Michael Graves View Post
    I own th 45N-1 and was having similar issues with focus when using a Toyo loupe. It did not have diopter correction and apparently recent eye surgery had affected my vision to the point that it was no longer a good match for my eyes. I purchased a Peak 7x with the ability to adjust for diopter correction and have been happier than a pig in s...I have not had any issues since.
    http://www.bhphotovideo.com/c/produc...ale_Loupe.html

    this one Michael?

    Damn expensive stupid hobby!!

  4. #14

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    Re: Chamonix Fresnel

    What I was wondering about was...
    I have an older plain and dim ground glass. If I replace the old groundglass and put in a Yanke screen, will my focus then be off.

  5. #15

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    Re: Chamonix Fresnel

    Quote Originally Posted by rknewcomb View Post
    What I was wondering about was...
    I have an older plain and dim ground glass. If I replace the old groundglass and put in a Yanke screen, will my focus then be off.
    That depends on the construction of your original GG. If the actual focus plane (frosted plane) of your screen is the front-most part then it'll be fine. If the fresnel is at the front then your focal plane will be off the thickness of the Fresnel.

  6. #16

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    Re: Chamonix Fresnel

    rknewcomb,

    To elaborate a bit on Old-N-Feeble: Since you have just a ground glass screen and no Fresnel at this point, you need a Fresnel-ground-glass sandwich in which the Fresnel is mounted behind the ground glass, i.e, where the frosted surface of the ground glass is closest to the lens and the Fresnel part of the sandwich is closest to you when you are viewing the image.

    Yanke makes several products: a thin Fresnel screen (0.85mm) that placed in front of the ground glass (you don't want this one), a thicker Fresnel screen that can be placed in either position (which would work for you, but you need to keep your original ground glass), or a Fresnel-ground-glass sandwich (which would also be fine for your application and would replace your ground glass).

    Some sandwiches have the opposite configuration, and they will cause a focusing error if you use them. You should, however, be fine with a Yanke screen if you get the one of the proper ones.

    Best,

    Doremus

  7. #17

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    Re: Chamonix Fresnel

    Thanks Doremus for explaining that. It is most helpful!
    Robert

  8. #18
    Luc Benac lbenac's Avatar
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    Re: Chamonix Fresnel

    Well I just changed my 45N2's gg/fresnel for a Hopf GG. First impression is very good. Waiting the week-end to try it out in the field.

    Cheers,

    Luc
    Field # ShenHao XPO45 - Monorail # Sinar F2
    6x6 # Minolta 1965 Autocord, 6x9 # Kodak 1946 Medalist II



    http://www.lucbenacphoto.com/

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