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Thread: How sharp can you get?

  1. #71
    David J. Heinrich
    Join Date
    Oct 2008
    Posts
    575

    Re: How sharp can you get?

    Quote Originally Posted by bensyverson View Post
    Actually, lots of people claim to have issues with film flatness when using standard LF film holders. The theory is that while rollfilm can be stretched and pressed onto the film aperture, sheet film can "rattle around" within the guide rails.

    I've never had problems with film flatness, but I shoot color film, so what do I know? I'd probably never see the difference.
    I think that's a lot of nit-picking. For things where you'd want everything in focus, the lowest you'd go is f/11 while using tilts. That's still around being equivalent to f/3 for a 35mm camera. Not microscopic DOF.

    From what I've read, that's more of a problem on some of the poorly made film-holders, and more-so for 8x10 where pointing down. I've held junk-film in the holder upside down and I see no noticeable bow in the film. When focusing my 90/4.5 even wide-open, I don't see real noticeable changes in DOF if I move the rail less than a mm.

    I think this would matter most if you're doing very narrow DOF work with lenses wide-open, like my 135/3.5, which would be like using a 38/1 on 35mm. I'll have to see if I notice anything there with problems with DOF when doing very shallow DOF work. But even so, probably the much greater factor is going to be subject movement if it's a person.

    Btw, when stopping down, beyond f/22, I think film-flatness hardly means anything at all. My first piece of film, I jammed in the same way the dark-slides go (I didn't realize it had to go the other way, behind the rails). So it was jammed in there, completely misaligned, not anywhere near standards. At with my 203/7.7 at f/45, I still got a very tack sharp exposure. That's a huge screw-up (on my part) beyond any kind of film-flatness issues you're going to see, but it still turned out ok for a large f-stop.

  2. #72

    Join Date
    Sep 2003
    Location
    South Carolina
    Posts
    5,165

    Re: How sharp can you get?

    Quote Originally Posted by dh003i View Post
    I think that's a lot of nit-picking. For things where you'd want everything in focus, the lowest you'd go is f/11 while using tilts. That's still around being equivalent to f/3 for a 35mm camera. Not microscopic DOF.
    With small sheet film (4X5 and 5X7) I don't believe that the film moving around in the guides will cause a loss of resolution, so long as it does not sag. Large sheet film will definitely sag if the camera is pointed down.

    The bigger issue for resolution is that the T-dimension of film holders varies quite a bit, even with ANSI made holders. This probably will not make a difference at f/22 with 4X5 fillm, but it can definitely make a difference in testing film for resolution at f/5.6 or f/8.


    Sandy

  3. #73

    Join Date
    Dec 2006
    Location
    Chicago, IL
    Posts
    1,420

    Re: How sharp can you get?

    My biggest problem with the M7 is focusing accuracy at close (portrait) ranges. Sometimes it's dead on, other times, it's not. Given what the lenses are capable of, I don't think any rangefinder on earth could match them.

    Also, having been spoiled by LF, the lack of movements would keep me from doing critical work with it.

  4. #74
    David J. Heinrich
    Join Date
    Oct 2008
    Posts
    575

    Re: How sharp can you get?

    Quote Originally Posted by sanking View Post
    With small sheet film (4X5 and 5X7) I don't believe that the film moving around in the guides will cause a loss of resolution, so long as it does not sag. Large sheet film will definitely sag if the camera is pointed down.

    The bigger issue for resolution is that the T-dimension of film holders varies quite a bit, even with ANSI made holders. This probably will not make a difference at f/22 with 4X5 fillm, but it can definitely make a difference in testing film for resolution at f/5.6 or f/8.

    Sandy
    I've read that the old Riteway holders with the metal light-guards are some of the best at compliance with standards and keeping the film in place. I also read that some of the older wooden ones are a class above other film holders, partly because they can be disassembled and completely cleaned; although I don't know about wood.

  5. #75

    Join Date
    Jun 2005
    Posts
    52

    Re: How sharp can you get?

    I gave up my 4 x 5 to use a Mamyia 7. I found using a tripod when shooting 1/30-1/60 sec makes a big difference in sharpness. The range finder couple does require adjustment, especially if the equipment gets banged around a lot. The repair people I have talked with mentioned that this is not unusual with several rangefinder cameras. I also found that after I shot several rolls of test film I could get very accurate with the focus and require almost no cropping. I still shoot 8x10 and 5x7, however I just returned from Europe after shooting with medium format for the first time and it was a pleasureable experience.

    Tom

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