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Thread: Blurry Focus on 4x5 Portraits

  1. #1

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    Mar 2021
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    Blurry Focus on 4x5 Portraits

    I keep coming up against a problem where the focus on my portraits is not quite right , despite using a loop and double checking. My loupes are x10 and x12. When I focus I make sure to center on the eyes, moving and back and forth until I'm certain I've reached the sweet spot. Despite this many of my portraits keep coming out a little soft, and seemingly just fraction or two out of focus. I'm typically shooting at fF5.6.

    I don't seem to have this issue with landscapes, but I'm assuming that's because I typically shoot at a much narrower aperture (f22 for example).

    Recently I have been using a lightweight travel tripod after losing a part for my heavy one. Could it be a vibration issue? Again, this issue does not occur on the same tripod when shooting landscapes.

    I have included some examples of the issue I have been encountering. This issue has only occurred outdoors. I have included an image of accurate focus indoors from the exact same setup.

    Thanks in advance for your help!

    Attached Thumbnails Attached Thumbnails Pierrot.jpg   John .jpg   Josh 003.jpg   Phil_2.jpg  

  2. #2

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    Re: Blurry Focus on 4x5 Portraits

    You definitely seem to have a focus issue. Two recommendations I can offer are (1) use a heavier tripod and (2) look at a DOF table. Portraits with LF are hard enough so eliminating possible sources of problems is a good thing to do. Also be aware that subject movement can be part of the problem. With narrow DOF it doesn’t take much of an unconscious shift or sway to blow the focus.

  3. #3

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    Re: Blurry Focus on 4x5 Portraits

    I would shoot at least one sheet of film at a test target to check the ground glass is aligned properly. If you don't have a test target shooting something like a letter at 45 degrees will work. Personally, I would just shoot at a smaller aperture, why make life difficult for yourself unnecessarily?

  4. #4

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    Re: Blurry Focus on 4x5 Portraits

    If the problem is consistently a slightly forward, i.e., toward the camera, focus plane, I would first check the GG alignment, as indicated above. That is, the plane of the ground glass is not the same as the plane of the film when loaded in the holder. Find someone with callipers who can measure this precisely.
    Philip Ulanowsky

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  5. #5

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    Re: Blurry Focus on 4x5 Portraits

    Quote Originally Posted by Tobias Key View Post
    I would shoot at least one sheet of film at a test target to check the ground glass is aligned properly. If you don't have a test target shooting something like a letter at 45 degrees will work. Personally, I would just shoot at a smaller aperture, why make life difficult for yourself unnecessarily?
    Thanks! I suppose I can shoot at f8 or f11, but I love the creaminess of f5.6, especially on large format. There's a local photo coop that might have a test target I can use.

  6. #6
    Tin Can's Avatar
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    Re: Blurry Focus on 4x5 Portraits

    as suggested shoot a yardstick at 45 degrees

    MARK the yardstick
    Tin Can

  7. #7

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    Re: Blurry Focus on 4x5 Portraits

    A lot of Plasmat type lenses are hard to focus for wide open shorts as they usually have prominent positive spherical aberration (SA) in the outer zones of the pupil and negative spherical aberration in the middle zones of the pupil. When both types of SA are present, it's hard to decide for which of the pupil zones to focus. I avoid using my Convertible Symmars stopped less then to f/11.

    Also, the somewhat softish pictures with both the negative and the positive SA present, look focused at slightly different distances depending on the magnification of the print/image. The finest details visible in serious enlargements only are the sharpest in one part of the subject, and the coarser details that attract the viewer's attention in small enlargements and contact prints are the most sharp in different parts of the subject. You probably do not enlarge your pictures 10x or 12x times. That means your loupes are not the most appropriate for the task. You may want to try a 3x (or thereabout) magnifier.

  8. #8
    multiplex
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    Re: Blurry Focus on 4x5 Portraits

    what shutter speed do you use indoors and out, do you use a shutter release?
    sometimes people have a hard time standing still.

  9. #9

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    Blurry Focus on 4x5 Portraits

    I had equivalent problem with my graflex crown graphic. After many test my conclusion was that focus plane was 0.3mm behind grown glass. To correct it I supplemented the film holders for this camera using wood edging (aprox. 0.3mm).

    For calibration I used my Schneider Xenar 210 f4.5 (the depth of field is very sort) and a calibration chart.

    Click image for larger version. 

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    Last edited by Pedro_fiz; 11-Sep-2022 at 07:58.

  10. #10

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    Blurry Focus on 4x5 Portraits

    I am attaching a photo with the Xenar at maximum aperture after the adjustment. The focus was perfect.

    https://flic.kr/p/2mgwQHA

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