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Thread: Chamonix Fresnel

  1. #1

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    Chamonix Fresnel

    I just got a Chamonix 45n-2 and really love the camera. Exactly what I was looking for and couldn't be more pleased with it.

    EXCEPT

    Not sure I'm into the fresnel. I've never really used one before. It feels like the image never gets really sharp for focusing, even with the loupe. I don't have a proper view camera loupe, I bought the cheap Peak 5x that someone here recomended, so it could be that the loupe is not properly focused on the ground glass.

    Anyway, from reading a bit about the Chamonix and the Fresnels, it seems like it can only be replaced by the factory? Do I have that right? If I took off the Fresnel myself, would I be able to use the camera with just the groundglass? Would I be able to replace the Fresnel myself?

    Thanks
    Paul

  2. #2

    Re: Chamonix Fresnel

    Get a good loupe first before anything else.

  3. #3

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    Re: Chamonix Fresnel

    Quote Originally Posted by sully75 View Post
    It feels like the image never gets really sharp for focusing, even with the loupe.
    That's correct, for off-center with wider-angle lenses. The center has no issues.

    If your loupe has a removable base, take it off and hold it close to the groundglass to get perfect focus (on the loupe).

    With that said, I quite like the fresnel+gg... done a lot of shots with it without even using a loupe and gotten them sharp:

    Nikkor 65mm f/4 SW wide open:
    http://www.flickr.com/photos/genotypewriter/6834544293

    Xenotar 150mm f/2.8 wide open:
    http://www.flickr.com/photos/genotypewriter/6806479707

    (Anyone who's not familiar with flickr, right click on the images and select 'original' to see approximately 12MP images.)

  4. #4

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    Simply turn you loupe around, using the base as a sort of eyepiece and then move your head and loupe (as a unit) closer and farther from the ground glass until it is in focus. Yes, you have to find the right spot and hold it there without resting anything on the ground glass, but this works really well with Fresnel screens.

    For shorter lenses that are often more of a focusing problem with Fresnel screens you can now change the angle of the loupe to the ground glass to find the sweet spot, i.e., somewhere not exactly perpendicular to the ground glass. The correct angle is always in line with the lens, easy to find.

    If you focus on the frosted/ground side of the ground glass, you should have a sharp image this way. I've been focusing for years like this and would never go back; it's just more convenient for me.

    FWIW, I have cameras with both Fresnel and plain ground glass and have no problems with either. The advantage to the Fresnel is that I can often dispense with the dark cloth. That's never the case with plain ground glass.

    There have been a few discussions here and on APUG about focusing lately. A quick search should turn them up.

    Best,

    Doremus

  5. #5

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    Re: Chamonix Fresnel

    Quote Originally Posted by genotypewriter View Post
    That's correct, for off-center with wider-angle lenses. The center has no issues.
    This was correct for the 045-N1 but according to Hugo has been corrected with the 045-N2, so off center and wider-angle lenses should no longer cause focus issues. The fresnel on the -N2 has been mounted on the outside of the gg, not the inside (and a protective glass is placed outside the fresnel, so it is now a sandwich).

  6. #6

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    Re: Chamonix Fresnel

    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.
    Michael W. Graves
    Michael's Pub

    If it ain't broke....don't fix it!

  7. #7

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    Re: Chamonix Fresnel

    Quote Originally Posted by chuck94022 View Post
    This was correct for the 045-N1 but according to Hugo has been corrected with the 045-N2, so off center and wider-angle lenses should no longer cause focus issues. The fresnel on the -N2 has been mounted on the outside of the gg, not the inside (and a protective glass is placed outside the fresnel, so it is now a sandwich).
    There are no focus issues in the sense where the gg/fresnel is placed at a wrong distance. I think this was the problem with the first version. Please correct me if I'm wrong.

  8. #8
    Unwitting Thread Killer Ari's Avatar
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    Re: Chamonix Fresnel

    The loupe of which you speak was probably my recommendation; I've used it for years without problems.
    I have a Linhof with a Yanke GG/fresnel and a Wista with the same type of screen, and both work very well with the Peak 5x loupe.

    I'm not familiar with Chamonix accessories, but I used to wrestle with separate GGs and fresnels, now I much prefer when they are one piece; brightness is much more even, as well.

  9. #9

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    Re: Chamonix Fresnel

    A somewhat related question...
    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?
    thanks!
    Robert

  10. #10
    Unwitting Thread Killer Ari's Avatar
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    Re: Chamonix Fresnel

    Quote Originally Posted by rknewcomb View Post
    A somewhat related question...
    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?
    Robert
    No; it is one piece, with a plain acrylic overlay.
    Pretty hard to screw up, much like the superior Wista screen.

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