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  1. #161
    Stephen Benskin's Avatar
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    Originally Posted by Stephen Benskin
    Every successful photograph I make shows theory. Isn't that the foundation of your defense of the Zone System? The quality of Ansel Adams' work is proof of the theory.

    Originally Posted by CPorter
    Putting it in terms of theory is certainly acceptable, but the foundation of my defense of the Zone System lies in learning how valuable (to me) the process of visualization can be. My photographic "craft" is leaps and bounds from what is was, because of the Zone System, and being proficient in the craft of photography is the path to becoming better at visualization, IMHO.

    Quote Originally Posted by CPorter View Post
    Your're right, it is not mentioned to any appreciative manner that even remotely resembles the type of discussions that occur here, yet his work speaks for itself, how important was it to him, I don't know, just asking.

  2. #162

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    Hi CPorter,

    I guess all I'm saying is that in The Negative (and many other books, articles etc) flare should be explained, particularly because the recommended film testing methodology does not involve contacting a step tablet. So it again comes back to the interpretation of test results. The effects of non image forming light might be useful to the reader when looking at the curves generated.

    Let me ask you this - why a 1/3 to 2/3 stop reduction in exposure when you suspect significant flare effects?

    Michael

  3. #163
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    Quote Originally Posted by Michael R 1974 View Post
    Hi CPorter,

    I guess all I'm saying is that in The Negative (and many other books, articles etc) flare should be explained, particularly because the recommended film testing methodology does not involve contacting a step tablet. So it again comes back to the interpretation of test results. The effects of non image forming light might be useful to the reader when looking at the curves generated.

    Let me ask you this - why a 1/3 to 2/3 stop reduction in exposure when you suspect significant flare effects?

    Michael
    For one explanation see Dunn & Wakefield Exposure Manual, in edition 3 there is an explanation with graph on page 19.

    Essentially flare lifts the toe of the curve more and more as exposure rises reducing effectively contrast on the film. Lower exposure levels when there is significant flare can provide better separation of tones.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  4. #164
    David Allen's Avatar
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    "Choose a film and developer you use often, and be sure to use the same camera, shutter and lens throughout. Your exposure meter, lens diaphragm, shutter, and darkroom thermometer must be reliable----calibrated by a technician if possible. Once this "system" has been tested, any variations introduced by a change of equipment (such as the possible difference in aperture calibration or flare introduced by changing lenses) should be quite apparent if they are significant. For a change in film and/or development, of course, new tests must be conducted."

    Adams' description here may appear 'wooly' in terms of flare but the key sentences are:

    "be sure to use the same camera, shutter and lens throughout" - the reason for this is that the testing procedure automatically compensates for flare.

    "any variations introduced by a change of equipment (such as the possible difference in aperture calibration or flare introduced by changing lenses) should be quite apparent if they are significant." - i.e if you have calibrated with one camera, one lens, one meter, one developer, one thermometer, etc introducing a variable such as a different lens will immediately show if flare, for example, is a significant factor. If it is, you then know that you need to re-calibrate for that particular lens by redoing the testing sequence.

    Often, particularly with 35mm/roll film users, you will hear comments such as 'my 28mm lens is rather soft compared to my other lenses'. This is actually the photographer describing that a particular lens has more flare (or indeed a different level of coating on the lens) than the others.

    A friend of my father - the late photographer James Ravilious - was unhappy with his Leica kit. The reason for this was that he couldn't consistently get the particular results he wanted. James preferred the softer look of older Leitz lenses before the advent of computer re-calculation and multiple coatings on the lenses. His problem was easily solved by getting rid of the newer lenses and buying lenses from the late 1950s. These gave the 'look' that he wanted with consistent tonality. In effect a matched set of lenses that all demonstrated the same level of flare which meant he could do one set of tests and then move on without having to worry.

    The lesson here is that, for 35mm and roll film users especially, the goal should be to get a matched set of lenses. In doing so, one can disregard all of the additional theory and get on with the most important aspect of photography - enjoying it!

    Best,

    David
    www.dsallen.de

  5. #165
    markbarendt's Avatar
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    David I agree with your Analisys of Adams' method and the observation about how lenses affect the result but a matching set of lenses?

    Much of the reason I settle on various lenses is to get various qualities, much more than a focal length change. Mamiya's 150SF is a great example. It can be adjusted to be sharp, f8 or smaller varying amounts of soft can be dialed in as needed with larger apertures, its an exceptional goto lens for portraits and landscape and snaps. This provides for a bit more work when printing but that's ok.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  6. #166

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    Quote Originally Posted by markbarendt View Post
    For one explanation see Dunn & Wakefield Exposure Manual, in edition 3 there is an explanation with graph on page 19.

    Essentially flare lifts the toe of the curve more and more as exposure rises reducing effectively contrast on the film. Lower exposure levels when there is significant flare can provide better separation of tones.
    I know the effects on the curve. I'm challenging the notion reduced exposure can provide better separations. To me it seems like if anything it would have the opposite effect since it shifts more of the exposure values into the part of the curve where compression is taking place.

    Regarding the sources of flare in testing etc, again, I'm refering mostly to flare caused by the subject/test target, not the lens. The kind of "veiling" lens flare Adams refers to is likely a relatively minor issue with most contemporary lenses.
    Last edited by Michael R 1974; 01-28-2013 at 07:06 AM. Click to view previous post history.

  7. #167
    CPorter's Avatar
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    Quote Originally Posted by Michael R 1974 View Post
    Let me ask you this - why a 1/3 to 2/3 stop reduction in exposure when you suspect significant flare effects?

    Because flare introduces some amount of unwanted density.

  8. #168

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    But the effect of flare is increasing compression below say Zone V. So doesn't reducing exposure simply move more of the image values into the area where local contrast is compressed?

  9. #169
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    Who is this Henry you guys are talking about? I couldn't find where he is first mentioned in this long thread.

  10. #170
    Stephen Benskin's Avatar
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    Quote Originally Posted by David Allen View Post
    "be sure to use the same camera, shutter and lens throughout" - the reason for this is that the testing procedure automatically compensates for flare.
    We've discussed this point on a number of occasions. In fact, this was the topic of Michael's question. Long story short. It doesn't compensate for flare. Flare is caused by higher luminances affecting lower illuminances within an optical system. Traditional ZS testing uses a middle gray target of a single tone. Even if flare existed, the influence of flare diminishes as you move up the curve. The metering of the target and stopping down may produce the shadow exposure but it's still the middle tone luminance where even in normal flare conditions, there is little influence. And this is completely separate issue from the question of introducing such a variable into a test.

    This is a good example of my earlier topic about the helpfulness of understanding theory. Helpful not so much as part of achieve precision testing. That's not necessary for most photographers. It's helpful in knowing the limitations of the tests.

    "any variations introduced by a change of equipment (such as the possible difference in aperture calibration or flare introduced by changing lenses) should be quite apparent if they are significant." - i.e if you have calibrated with one camera, one lens, one meter, one developer, one thermometer, etc introducing a variable such as a different lens will immediately show if flare, for example, is a significant factor. If it is, you then know that you need to re-calibrate for that particular lens by redoing the testing sequence.
    This can only be true if the photographer shoots with the same lens at the same f/Stop and shutter speed. And this is a good example of my other point about good testing and bad testing. My contention is that speed testing isn't necessary for most and the only testing really needed is for contrast (and that only applies to maybe 10% of photographers). In order to achieve knowable, quantifiable results, the variables and testing conditions must be known and controlled. In other words, scientific testing. Many of the disagreements about testing come from people arguing from different perspectives. It isn't a question of which is more accurate. But there's a big difference between testing for film speed (scientific) and testing for EI. They are different things and have different purposes.

    Sorry, ran out of time.



 

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