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Thread: LF lenses: are they really sharp?

  1. #1

    LF lenses: are they really sharp?

    I recently had an opportunity to shoot a 150 strong group of people with a building in the background. I made a few shots on a 6x12 rollfim back with the 110XL at f16 and I secured the taking with the Pentax 67 and a 75mm lens at f16. The 6x12 shots are so weak compared to the 6x7 that I am contemplating throwing my 4x5 outfit into the lake. I am joking of course, no use of writing to me privately to offer adoption. But by the time I shot with the Pentax, people were a bit weary and so I have to use the 6x12 shots. If film flatness or focus were the problem, I would see some sharp and unsharp portions of film as the depth of field started at a dozen yards and reached infinity, but the film is just evenly unsharp. When I say unsharp, I mean it's decent, but unsharp compared to the 6x7 shots. I always thought the 110 XL was a sharp lens, but I am quite puzzled now! Any comment?

  2. #2
    the Docter is in Arne Croell's Avatar
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    LF lenses: are they really sharp?

    Paul, can you elaborate a bit more on the differences and the conditions when they are visible? For example:

    At what magnification is the difference discernible? Is it more a resolution or contrast difference, or both?

    If its contrast, the one explanation I can offer is that the 110XL has a huge image circle compared to the 6x12cm format you used which leads to a lot off non-image forming light bouncing off the inner walls of the bellows reducing contrast - unless you used a compendium in front of the lens.

  3. #3

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    LF lenses: are they really sharp?

    I've heard that earlier versions of the 110XL did have sharpness problems, but this was addressed in later versions. Perhaps you have an early version of the lens? I have a 110XL (purchased new just over a year ago), and I've never had anything but sharp images from it.

  4. #4
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    LF lenses: are they really sharp?

    Hi Paul,

    The Schneider 110XL is a very sharp lens. However, F22 (or a smaller aperature) probably would have been a better choice than the f16 aperature you used. Of course, it could have been your eyes, when you focused on the groundglass. My guess, look for your rollfilm back to be the basis for the problem, not your lens.

  5. #5

    LF lenses: are they really sharp?

    Arne, the difference is in resolution only, both type of shots look exactly the same until you zoom in right into the faces of the people. Then it becomes evident that the 6x7 shots have a lot more to them. Well, I always knew that most MF lenses are sharper than LF lenses just as SF lenses are sharper than MF lenses. It's just that I am surprised to see that a panoramic crop representing half the film surface of a 6x7 contains more detail than a whole 6x12 frame!

  6. #6

    LF lenses: are they really sharp?

    Eugene, you are right about f22 being a better choice. It was dimm and I was already at 1/15 on 400 ASA Provia. A curved or popped film should show at least some sharp areas I suppose. Ken, my sample is an early one... I must say that my 4x5 shots always satisfied me and gave me an impression of sharpness. It's just that I am suddenly aware of how sharper are the MF lenses!

  7. #7
    Moderator Ralph Barker's Avatar
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    LF lenses: are they really sharp?

    Assuming the on-film magnification factors are similar, I don't think the 6x7 vs 6x12 is really a "crop" in the sense that you're making the comparison, Paul, as it's essentially just cropping off the sides.

    Given your situation, I'd also suspect the 6x12 rollfilm holder as being the source of the problem - potentially both in terms of film flatness and in positioning with respect to the ground glass.

  8. #8
    the Docter is in Arne Croell's Avatar
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    LF lenses: are they really sharp?

    Your description suggests a difference of at least a factor of 2 in resolution - that is more what I would expect, and also more than what the numbers on <a href="http://www.hevanet.com/cperez/"> Chris Perez's web site <a> suggest. My suggestion would be to repeat that "test" (without the people of course) under more controlled conditions and check again.

  9. #9

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    LF lenses: are they really sharp?

    You've measured film plane vs. ground glass with film in the back? Sometimes we make the "leap" since there's no problem with film holders and just put something like a 6X12 roll back in and figure surely it's "right on" especially considering what you paid for it. I'd check with a Starret last word type dial indicater and prove that the film is indeed at the same plane as the ground glass. At F16 that Schneider should resolve almost identically to the 75 P67. I just had the same thing happen with the 8X20. But luckily my big neg is robust. But like you by the time I got to the smaller camera people were picking their noses etc. etc.

  10. #10
    wfwhitaker
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    LF lenses: are they really sharp?

    Sounds like you never were really in focus to begin with. As Ralph and Jim suggested, check your ground glass alignment.

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