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Thread: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experience.

  1. #1
    Thalmees's Avatar
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    Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experience.

    Tolerance of Fidelity 11X14 Holders; Flatness Issue ?
    Hi Folks,
    Good morning/evening and thanks in advance for your valuable contribution/help.
    Wondering how much a film holder should be flat, specially the ULF Fidelity 11X14 ?
    Just acquired a used pair of them, thought Fidelity is the best among others specially wood types.
    Did not yet used them. But did a simple flatness test. I aligned both holders parallel, each holder is resting on the Rib-lock of the other holder. If both holders are flat, the space between them should be the same in the middle and at both ends.
    .
    Unfortunately, I noticed they are curved away from each other at center when aligned parallel. A larger space between the two holders at the center compared with the space at both ends.
    The opposite alignment produces opposite observations. The space between the two holders at the center is narrower(holders actually touching each other) compared with the space at both ends.
    .
    Here are some photos at center and at both ends, to compare the space between both holders, and to conclude on their flatness. Each pair of photos was taken at the same alignment scenario:
    Click image for larger version. 

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    .
    I think, plastic holder specially the LF/ULF, when stored in a hot weather for enough time, can lose its flatness.
    Now, my queries:
    1. Is it normal for used Fidelity 11X14 holders ? Holders by the way are in excellent cosmetic condition.
    2. Does it affect sharpness on 11X14 film ?
    3. Can that magnitude of curvature be covered by the depth of focus at say f/32 in landscape photography ?
    4. Is it correctable ?
    .
    Thanks so much again, and please enjoy your time.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

  2. #2
    Thalmees's Avatar
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    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    Hi all,
    Thanks for looking. But, looking(only) is not the norm here.
    Though not frequent poster, I had great help before, really appreciated.
    BTW, the holders was Not acquired from any member in this wonderful forum, Not acquired from any LFP forum.
    Thanks so much.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

  3. #3

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    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    Since no one more knowledgeable has chimed in, I will offer an opinion: the amount of warpage that you see is probably not automatically significant. If it is enough to let light in past the rebate that the holder drops into, then it is clearly unacceptable, but if you look for posts regarding the depth of the rebate (folks making new backs, investigating old cameras, etc.) you will find that there is a good bit of variation. I can't recall anyone who had firmly established that the error (with respect to the old ANSI standard document) was negatively impacting his images.

    The obvious thing to do is to make a test; focus as sharply as possible in the area of the groundglass that matters most to you, and use a sheet of film or paper to find out if the negative is noticeably more blurred than the groundglass image was. You can improve this test somewhat by using a strong green or blue filter, in case your lens has chromatic aberration.

  4. #4
    ic-racer's Avatar
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    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    If you are shooting at f64 then you may be allowed 10mm of leeway (5mm on each side of the film plane, depending on multiple factors) and still have sharp negatives. ( http://www.largeformatphotography.info/fstop.html )

  5. #5

    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    Since I have some experience in this arena I thought I would chime in. I have quite a number of Fidelity 11x14 medical cassettes that I use so I went downstairs and pulled a couple to check.

    First of all it is my opinion that checking for flatness you need to take the rib lock out of the equation (it is nothing more than a calibration reference of non concerning thickness) if you really want to check this properly. Take the rid lock out of the equation and lay the holders against each other. Mine are absolutely as flat as a pancake and absolutely perfectly flat to each other. Secondly lay the holder over a countertop with the rib lock over the edge and out of play and use a flashlight to check its flatness. Again, the ends are perfectly flat with both of my Fidelity holders that I checked. I can send pics if this would help.

    Bear with me in setting up this conclusion. After acquiring a Deardorff v11 camera with a non film holder back, I had Richard Ritter make me a 11x14 back and it was set up for my S&S wooden 11x14 holders. When the new Deardorff company went into business I acquired an original Deardorff GG back. Shortly thereafter I had acquired about ten like new 11x14 Fidelity cassettes that I wanted to use. After coming back from a field excursion where I used the medical cassettes with the Ritter back that was set up for the S&S holders, the less than blazingly sharp results I expected with the slightly macro image I made caused me to have a good friend of mine use his machinist skills to see what was going on between these holders/backs. I focused this with absolute precision so something was going on.

    What the machinist concluded was using the same T Max 400 sheet film thickness in both holders the Fidelity Medical cassette had a probe depth different (shallower) than the S&S holders that required a shim adjustment under the Deardorff GG to raise it to get it to acceptable industry standards. As a result I left the Ritter back alone to use the S&S holders exclusively (since this back was absolutely spot on) and the Deardorff back was aligned to use the Fidelity Medical Cassettes. My machinist friend also commented that the Fidelity holders that he checked all had a very slight curvature to the center of the holders likely was a result of the manufacturing process as they have an aluminum plate center that had to be molded with considerable heat in the process. Now I have two backs optimized for holders that have differing dimensions but work fine. At the end of the day the circle of confusion was such that if I wanted to make a macro shot I would opt for the Ritter back and the S&S holders. For normal shooting as long as I use the proper holders in the correct back set up for it what little curvature is in the Fidelity holders is visually inconsequential. Hope this helps!

  6. #6
    Tin Can's Avatar
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    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    When I bought my Deardorff SC11 back to use on my SC11 box, I found my factory back to be at least 1/8" in deviation to ANSI standards. I sent my back to Richard Ritter and he installed his custom GG frame and bail handle he also made 11x14 film holders to match.

    I think we are all saying, holders must be flat and dimensionally correct to the back in use. The critical distance is called 'T'. 'T' as called out in this ANSI spec. http://home.earthlink.net/~eahoo/page8/filmhold.html

    Warpage as you seem to have, is not a desirable trait in any holder. Perhaps yours were overheated while in a bad position, like leaning in storage.

  7. #7
    Thalmees's Avatar
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    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    Quote Originally Posted by Harold_4074 View Post
    ... the amount of warpage that you see is probably not automatically significant. If it is enough to let light in past the rebate that the holder drops into, then it is clearly unacceptable, ...
    ... make a test; ... use a sheet of film or paper to find out if .... You can improve this test somewhat by using a strong green or blue filter, in case your lens has chromatic aberration.
    Thanks so much Harold.
    Very valuable and specific points. Some I forgot, others really new to me.
    Highly appreciated.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

  8. #8
    Thalmees's Avatar
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    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    Quote Originally Posted by ic-racer View Post
    If you are shooting at f64 then you may be allowed 10mm of leeway (5mm on each side of the film plane, depending on multiple factors) and still have sharp negatives. ( http://www.largeformatphotography.info/fstop.html )
    Thanks so much ic-racer.
    That's what I hope for.
    The link is great.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

  9. #9
    Thalmees's Avatar
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    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    Quote Originally Posted by Michael Kadillak View Post
    Since I have some experience in this arena I thought I would chime in. I have quite a number of Fidelity 11x14 medical cassettes that I use so I went downstairs and pulled a couple to check.

    First of all it is my opinion that checking for flatness you need to take the rib lock out of the equation ...
    Secondly lay the holder over a countertop with the rib lock over the edge and out of play ...
    I can send pics if this would help.

    ...

    What the machinist concluded ... Fidelity Medical cassette had a probe depth different (shallower) than the S&S holders that required a shim adjustment under the Deardorff GG to raise it to get it to acceptable industry standards. As a result I left the Ritter back alone to use the S&S holders exclusively (since this back was absolutely spot on) and the Deardorff back was aligned to use the Fidelity Medical Cassettes. My machinist friend also commented that the Fidelity holders that he checked all had a very slight curvature to the center of the holders likely was a result of the manufacturing process as they have an aluminum plate center that had to be molded with considerable heat in the process. Now I have two backs optimized for holders that have differing dimensions but work fine. At the end of the day the circle of confusion was such that if I wanted to make a macro shot I would opt for the Ritter back and the S&S holders. For normal shooting as long as I use the proper holders in the correct back set up for it what little curvature is in the Fidelity holders is visually inconsequential. Hope this helps!
    Definitely, it help much Michael.
    Thanks sooooo much.
    Did the tricks, and I can see more now.
    Will test to decide on shimming of the GG and to see how light tight is the holders on the camera back.
    It's a pleasure to read your post.
    Thanks so much.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

  10. #10

    Re: Tolerance of Fidelity 11X14 Holders; Flatness Issue ? Please share your experienc

    Quote Originally Posted by Thalmees View Post
    Definitely, it help much Michael.
    Thanks sooooo much.
    Did the tricks, and I can see more now.
    Will test to decide on shimming of the GG and to see how light tight is the holders on the camera back.
    It's a pleasure to read your post.
    Thanks so much.
    My pleasure fellow ULF shooter. We are a small group and we need to encourage each other to keep things vibrant and dimensional in the supply areas.

    Here is a suggestion to try to assess the mating of your Fidelity Holders and your camera back. Insert a holder in the your camera back and extend your bellows out maybe 15" or so in a dark room. Turn off the lights and with one of your hands holding a small flashlight reach into the bellows from the lens board opening and shine the light at the four corners and the edges of your inner ground glass back and look from the outside at any light that may be visible from the inside of the bellows/camera that would indicate warping or a poor mated surface. The use of a machinists probe micrometer and the assessment of the depth of the inside surface of the GG relative to the depth of a piece of sheet film inside of a holder is a challenging task with a camera that has such a large film area. Checking the accuracy of all four corners as well as the center of the film holder is equally rigorous. That is why I asked my machinist / photographer friend to help me with this task.

    Lastly, with all of my ULF photography I always use a dark cloth over the film holder while making an image. Given the costs of film and the angst you experience when you discover a light leak into your negative area it is what I call my insurance policy. This is a must with wooden holders and I just made it a universal habit in the field with these beasts.

    I am working with some 11x14 X ray film that appears to have some considerable promise. The incentive is the fact that it is $0.50 - $0.70/sheet. Will keep you posted.

    Cheers!

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