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Thread: A question about large format optics

  1. #1

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    A question about large format optics

    In a discussion with a friend recently, I maintained that there were optical qualities unique to large format that medium format digital could not reproduce, regardless of the power of resolution. I claimed that only large format lenses can reproduce things like the many gradations of focus, and that a small or medium format camera would always retain a certain optical affect that related to the physical size of the lenses and film area.

    My friend disagreed, saying that it has to do with the power of resolution. Small and medium format film cameras do not show a comparable gradation of focus because the film size is small in relation to the film grain, and that limited resolution power eliminates the optical clarity which large format film instead has. He claimed that, once full clarity is achieved with medium format digitally, that you would see that same optical subtlety as in large format, because that ratio of resolution power to film area would have been greatly increased to transcend the limits previously imposed by film. So he says it is not unique to large format, but is a question of resolution.

    I'm awl cornfused! Who is right?!

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    Re: A question about large format optics

    Does it really matter who is right? As long as the tools we use match our photographic vision, then the resulting image will express our artistry. All the rest is simply engineering.

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    Re: A question about large format optics

    Quote Originally Posted by claudiocambon View Post
    In a discussion with a friend recently, I maintained that there were optical qualities unique to large format that medium format digital could not reproduce, regardless of the power of resolution. I claimed that only large format lenses can reproduce things like the many gradations of focus, and that a small or medium format camera would always retain a certain optical affect that related to the physical size of the lenses and film area.
    I don't know what you mean by "gradations of focus". The optics of medium and large format lenses are basically the same. But any view camera, medium or large format, will allow placing the plane of exact focus, within limits, where you want it by tilting and/or swinging the standards. For the same scene with the same angle of view and point of view and same size final print, medium format actually provideds more depth of field at the same relative aperture, but diffraction will kick in sooner.

    My friend disagreed, saying that it has to do with the power of resolution. Small and medium format film cameras do not show a comparable gradation of focus because the film size is small in relation to the film grain, and that limited resolution power eliminates the optical clarity which large format film instead has. He claimed that, once full clarity is achieved with medium format digitally, that you would see that same optical subtlety as in large format, because that ratio of resolution power to film area would have been greatly increased to transcend the limits previously imposed by film. So he says it is not unique to large format, but is a question of resolution.

    I'm awl cornfused! Who is right?!
    Generally, medium format lenses are capable of somewhat higher resolution than large format lenses because the latter are usually designed for movements and have larger coverage than the format. Even so, many large format lenses compare favorably to typical meidum format lenses, so this may not be a significant factor. In any case, the obtainable resolution will be a combination of the resolution of the film and that of the lens. Since medium format has to be enlarged more for the same size final print, you are more likely to challenge the resolution limits imposed by the combination. I'm not sure what you mean by achieving full clarity digitally. Right now, digital backs for either medium or large format can't compare with film, although that may be possible in the not too distant future. If you were able to eliminate the resolution of medium, film or digital, as a singnificant factor---by making it much larger than that of the lens---then the resolution of the lens would be the limiting factor. Ideally, as noted above, a lens designed for medium format might be enough better than a comparable lens designed for large format, that, after accounting for the degree of enlargement necessary for the final print, you wouldn't be able to tell the difference. But I believe we are now pretty far from that situation. So, for the moment, if you are interested in resolving fine detail, you are more likely to be able to do it with large format than with medium format, at least for large prints which will be viewed close up.

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    Re: A question about large format optics

    You are right. Like most, he is only thinking in terms of ultimate sharp resolution. Even the jump from 4X5 to 8X10 makes an enormous difference in the out of focus rendition of a fast lens that covers the format. There is no way to duplicate how an f4 lens sees the world on an 8X10 camera. If the only thing in question is ultimate sharp resolution which is all the digital world has to offer, he'd be close. He's got about 3,000 X 4,000 chances for smooth rendition. Grain in 8X10 has billions.
    He is no fool who gives what he cannot keep..to gain that which he cannot lose. Jim Elliot, 1949

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    Re: A question about large format optics

    I suppose there is nothing wrong with a friendly debate over such things but the reality is there is no clear answer. Personally, I don’t even understand the question because I don’t understand what is meant by terms like “power of resolution”, “gradations of focus” and “once full clarity is achieved”.

    I happen to know a number of people who are consumed by the unending argument of “this piece of equipment is better than that piece of equipment.” They buy and sell and debate and argue and brag about their superior lens or camera or whatever and take considerable pride in owning “The Best”. They can recite nauseous amounts of data proving they are not wrong.

    Most of these people have never made a meaningful photograph in their life. Most of these people don’t even care about making photographs.

    If your interest is in making photographs, choose the tool that works for you and don’t worry about what the other guy is using. If I have a piece of equipment that is not performing to my standards, I replace it with something that will. I happen to use a 5x7 Linhof Technika and I have lots of lenses of various makes and focal lengths. My tools work for me. They might not work for people doing other types of photography but that is irrelevant.

    Jerome

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    Re: A question about large format optics

    I should specify, I am not interested in what is sharper as an abstract argument. I am interested to know whether there is a difference in optical affect between lenses of different formats.

    Let me be more precise about my example. I love the way I get focus fall off on a large format neg when I do a portrait up close: I hold the tip of the nose to the eye, and by the ear there is this beautiful transition as the focus falls off. What I would like to know is, is that optical affect a physical function of the large format lens, unique to that format, or merely the result of large format film's resolution power; if a medium format digital back had that power of resolution, would I get that same gradation of focus or not? That is why I am interested in understanding what the difference might be, if any, between the different formats.

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    Palladium is beautiful Christopher Perez's Avatar
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    Re: A question about large format optics

    If it really matters, I would ask your friend for Verifiable Objective Evidence to back up his/her statements. Not just theory or thoughts.

    The physics of optics does NOT change just because you go from medium format to large.

    I have looked a related questions (if I understand the nature of your question, that is) "six ways to Sunday" and have to agree with St. Ansel. Late in his life he said "...Knowing what I know now, any photographer worth his salt could make some beautiful things with pinhole cameras..."

    Which is, to me, a way of reminding us that cameras and lenses (or pinholes) are just tools to an end, not the end in themselves.

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    Re: A question about large format optics

    I consider the size and characteristics of the film to be more important than any magical or mythical difference in 35mm, MF, or LF lenses. Human vision is remarkably complex and sophisticated. We can subconsciously recognize differences between prints which, according to some technicians, should be essentially identical. This is where the size of the film (or more precisely, the degree of enlagement) becomes important.

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    C. D. Keth's Avatar
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    Re: A question about large format optics

    No, the optics don't really change. You could easily build a mount to put a LF lens on a 35mm slr, a hasselblad, or a DSLR. The results from all of those experiments would be roughly the same as any other len on the given format. The only real difference between LF lenses and others is that LF lenses don't focus, the cameras do.

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    Re: A question about large format optics

    I think there are differences in the transitions from in-focus to out-of-focus areas between formats (and similarily, the amount of your depth of field). This is just a function of the focal lengths (larger format = longer focal length for a given field of view) and circles of confusion (probably larger for larger formats because of smaller enlargemen factors). You can certainly get shallower depth of field with a larger format, and I think more gradual transitions from in focus to out of focus (ie, a moderate wide angle with focus gradually drifting off into the distance is harder with a smaller format and impossible with something like a pocket digital camera with a teeny sensor and relatedly small focal lengths).

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