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Thread: Horseman 6x7 back film flatness problem? Or not?

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    Horseman 6x7 back film flatness problem? Or not?

    Hi all,

    I've been going through the paces testing my new Linhof Techno, which I'm using with a Horseman 6x7 film back. I absolutely love the camera and lenses but am wondering if I'm experiencing a film flatness problem...

    I'm just not sure if I'm imagining it or not... On several occasions I've shot several frames of the same image at the same settings (usually f11, 1/125th, same focus exact point) and the second image is soft, seeming to be worst in the middle of the frame. I've not used an interchangeable 120 film back extensively before, having used mostly a Mamiya 7II setup for ten years, but I wonder if this is something people have heard of? It's not a big issue if I bracket but some of you have advise on how to avoid it if it is in fact a known issue an internet search brings up some forum threads but nothing really definitive. Are some backs or film emulsions better / worse than others in this regard? Just thought I might ask peoples opinion to help with the learning process along!

    The long and short of it is that I am very much looking forward to getting a digital back to round out the kit!

    Thanks,

    TJV

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    Re: Horseman 6x7 back film flatness problem? Or not?

    I used Horseman 6x12 backs a great deal and also their 6x7 backs--they have the same basic design. I never experienced the problem. Can you post an image? Is this a consistent problem? Does your film sit in the back for long periods?

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    Re: Horseman 6x7 back film flatness problem? Or not?

    Certain films I think, can be more problematic for film flatness. Efke 25 is quite thin, and when I develop it it's sometimes interesting getting it on the reel prior to emersion. I find the higher ISO films behave better, especially when trying to get them flat. My Fotoman 612 has 2 counter-rotating knobs on the top of the camera, that allows me to tighten the film plane just prior to exposure. It's probably the most useful feature! When loading your film try to hold the new roll with your thumb to gently put friction on it while you advance the take up spool. This helps to tighten the film, and if possible before exposure, turn the knob on the magazine to take up any slack.

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    Re: Horseman 6x7 back film flatness problem? Or not?

    Thanks guys. Good to know these problems aren't common.

    I've sent a few negs away for drum scanning to see what I'm dealing with – until now I've been inspecting the negs with a 10x lupe. What I'm seeing is kind of strange, and quite subtle, but I suppose I won't know for certain until I run more film through the system as well as inspect some properly scanned negs.

    As an aside, I really like the Horseman back. It seems to be built well enough and is very smooth in operation. I was going to pay extra for a full on Linhof Rollex 6x9 back but decided to go the cheaper way at the last moment. I'm glad I did as the price difference was insane!

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    Re: Horseman 6x7 back film flatness problem? Or not?

    Quote Originally Posted by tjv View Post
    ... On several occasions I've shot several frames of the same image at the same settings (usually f11, 1/125th, same focus exact point) and the second image is soft, seeming to be worst in the middle of the frame.
    Thanks,

    TJV
    Like others, I've not experienced roll film holder flatness issues before, I'm sure it can happen. If its the 2nd image, you might want to carefully monitor what you do when you wind the film on, is the holder seated firmly? Any chance you touch the front standard a bit heavy handed, I've noticed vertical movement, enough to affect infinity focus when removing Cokin filters by pulling them up out of the holder on light lenses.

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    Re: Horseman 6x7 back film flatness problem? Or not?

    Unless you have a back with a vacuum pressure plate, that actively pulls the film flat onto itself, film flatness is always an issue , whether or not it is big enough an issue for you to notice it. Factors that can effect the extent of it can include humidity, temperature, film base thickness and type, emulsion thickness, backing plate clamping pressure, film rail smoothness, winder tension and backlash and a whole lot more. The shorter the focal-length you use, the more critical film flatness becomes due to the shallower depth of focus (at the image plane, as distinct from DOF at the subject plane).
    Siebel
    "In the end, it's all about the pictures"
    www.bryansiebel.com

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    Re: Horseman 6x7 back film flatness problem? Or not?

    Thanks, guys.

    I think it might have been an anomaly but just wanted to check with others to see if they'd come across it before. I'm pretty sure in this instance it was a flatness issue but looking closely at my other negs under a loupe, it's not happening enough to worry about.

    This is all probably a case in point for testing gear properly before you put it to task. It's the little things with new camera systems that add up to make things quite confusing or overwhelming.

    For example, I've just gotten around to masking off the edges of my Silvestri ground glass frame so I'm not distracted by the image area that falls outside of the 6x7cm frame. Another thing, the edge markings on the ground glass and by extension the grid lines aren't centered – the edge of the metal GG frame is the actual image area edge, not the marked lines. This might be a simple thing but man, it has taken me a while to get my head around it when problem solving off my negs!

    I've got to say, I'm really liking the Techno. I can see how focusing in dim light on the smaller digital formats might pose problems for some – I'm used to the GG coming from 4x5" – but it's a truly great system. Very well built and a pleasure to use.

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