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Thread: Wista 45DX focusing problem, astigmatism? Try a bright screen?

  1. #11

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    Quote Originally Posted by Bob Salomon - HP Marketing View Post
    To adjust the focus of your loupe properly. Turn on a light in front of the camera, remove the lens. Focus your loupe on the ground glass until the grain of the gg is in sharp focus. Now put your lens back on and shoot.

    Assuming that you have a Wista gg and a Wista fresnel installed on your camera and assuming that you had not focused your loupe then when you placed your loupe on the fresnel and focused you were out of focus by the thickness of the fresnel + the thickness of the gg + any space between the 2.

    If you don't have the fresnel then you would have been out of focus by the thickness of the gg.

    In photographic terms those can be large errors in focus.
    Great, this is helpful. When I adjust my loupe I can focus either on a sand pattern (which I assume is the grain of the glass?) or on a series of concentric thin black lines (the fresnel?). I should focus on the sand pattern, right?

  2. #12

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    Quote Originally Posted by laphotographe View Post
    Great, this is helpful. When I adjust my loupe I can focus either on a sand pattern (which I assume is the grain of the glass?) or on a series of concentric thin black lines (the fresnel?). I should focus on the sand pattern, right?
    Correct.
    One man's Mede is another man's Persian.

  3. #13

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    The grain pattern.

  4. #14

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    Quote Originally Posted by laphotographe View Post
    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    I ran some tests based on Brian's and Vaughn's suggestions and I should have the film back in the next few days.
    any results yet? I too have astigmatism and would like to hear how you were able to solve the problem

  5. #15

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    Quote Originally Posted by grinalip View Post
    any results yet? I too have astigmatism and would like to hear how you were able to solve the problem
    So far the issue is only partially solved. I did adjust my loupe as per Bob's suggestion, and that was helpful. The focus tests also seemed to come back ok. However, I am still loosing more images that I would care to loose when I make portraits. The problem is not systematic, so I am having some help tracking it down. For what it is worth, I am being careful to focus with my head right side up (not upside down, as I often compose my photographs) so that my eyeglasses are definitely in the correct position for my eyes when focusing. Grinalip, have you found anything else that helped?

  6. #16

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    Quote Originally Posted by laphotographe View Post
    So far the issue is only partially solved. I did adjust my loupe as per Bob's suggestion, and that was helpful. The focus tests also seemed to come back ok. However, I am still loosing more images that I would care to loose when I make portraits. The problem is not systematic, so I am having some help tracking it down. For what it is worth, I am being careful to focus with my head right side up (not upside down, as I often compose my photographs) so that my eyeglasses are definitely in the correct position for my eyes when focusing. Grinalip, have you found anything else that helped?
    What are you focusing on when you take a portrait? What focal length lens? What f stop? What do you mean by a portrait? Head and Shoulders? 3/4? environmental? etc.

  7. #17

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    Quote Originally Posted by Bob Salomon - HP Marketing View Post
    What are you focusing on when you take a portrait? What focal length lens? What f stop? What do you mean by a portrait? Head and Shoulders? 3/4? environmental? etc.
    Hi Bob, thanks, I am working with a 135mm lens, generally stopped down between f8 and f16. I shoot at a variety of distances, and what I've noticed is that the closer photographs (head and shoulders) tend to be very crisp, but those a bit farther away (full body / environmental) are where the focus tends to be a little bit off. I focus on the eyeballs.

  8. #18

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    What lens? 135mm is too short for a head and shoulders shooting full frame 45. You will have fore shortening exagerate noses, chins, foreheads, etc.

  9. #19
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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    I found that for me the easiest way to adjust my loupe was to just take a pencil and write an "X" in the middle of the frosted side of the ground glass. This gives a target that makes for easy focusing of the loupe. I can use that X to quickly double-check the loupe in the field. Also, I use gaffer's tape to keep my loup properly focused--and, yes, the tape has left hard residue on the loupe after being there for a few years.

    Keith

  10. #20

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    Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?

    The lens is a Nikkor-W 135mm f/5.6, about 7 years old. I have found it to be very appropriate for portraits.

    Quote Originally Posted by Bob Salomon - HP Marketing View Post
    What lens? 135mm is too short for a head and shoulders shooting full frame 45. You will have fore shortening exagerate noses, chins, foreheads, etc.

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