Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,503   Posts: 1,543,430   Online: 848
      
Page 4 of 4 FirstFirst 1234
Results 31 to 39 of 39
  1. #31
    Stephen Benskin's Avatar
    Join Date
    Jan 2005
    Location
    Los Angeles
    Shooter
    4x5 Format
    Posts
    1,218
    Quote Originally Posted by Michael R 1974 View Post
    When the subject luminance range is long, we are taught to contract it to fit onto the paper. But this disregards the shape of the curve and the local contrast effects of modified development.
    This is true, but you shouldn't totally ignore that using the relationship between the negative density range with the paper's log exposure range can be an effective guide. And as with most things, things aren't as straight forward as you might expect. It doesn't make them wrong, just more complex.

    Jones discusses the best way to relate the film to the paper in two rather tedious papers, Control of Photographic Printing: Improvement in Terminology and Further Analysis of Results, 27 pages, and The Control of Photographic Printing by Measured Characteristic of the Negative, 60 pages. Both published in the Journal of the Optical Society of America. These are the studies that helped to establish the LER ranges for paper grades and the NDR/LER matching system. He looks at a number of different ways to "match" film to paper and concludes,

    "The procedure followed in obtaining a relationship between NDR and LER may seem forced and artificial. This we grant, and it must be born in mind that the print quality obtained by its use will not be the highest possible quality. But what other course is there to follow? Either we must make the best of a somewhat imperfect relationship or face the prospect of having no criterion whatever for choosing the paper contrast grade."

    This doesn't mean anyone should throw the baby out with the bath water. It just means there isn't system that works perfectly every time. I've attached a graph from Jones' testing showing the variance in negative density ranges that yielded first choice prints on a grade 2 paper. What Jones found was “for the soft papers, the density scales of the negative (DR) should in most cases exceed the sensitometric exposure scale of the paper (LER), whereas, for the hard papers, the density scales of the negatives should in most cases be less than the sensitometric exposure scale of the paper (LER).”

    Michael, the method of matching the NDR with the LER isn't broken, there are just other factors involved. And you have pointed one out. While it is acceptable to compress the values from the highlights and shadows, the mid-tone gradient must exceed the mid-tone contrast of the original subject for the print to be perceived as being of high quality. They found the mid-tone gradient generally needs to be over 1.10. To fit the values from a subject with a high luminance range onto the paper, it is likely the mid-tones have to fall below the 1.10 gradient level. So even though the NDR matches the paper LER, unless the mid-tone gradient is greater than 1.10, the resulting print will probably not be acceptable. (This is another reason I like to use multiple quadrant reproduction curves. The fourth quadrant compares the print values to the original subject values. It's a very useful analysis tool. In fact, I just uploaded two examples. Fig 1 is a classic example for Normal and Fig 2 is for a 10 stop luminance range. Even though both film and paper match, there is a major difference in the reproduction curve.)

    This all falls under the heading of subjective tone reproduction theory. I believe the third edition of the Theory of the Photographic Process best covers this subject. The biggest variable is that the end product of the photographic process is subjective. This is where variance and statistics come into play. You determine the way something generally works in order to produce some form of guideline to get you close enough most of the time to make it work.

    Another problem especially with long range subjects comes from the fact that paper can't reproduce specular reflections. In order to produce any tones above the reflectance of the paper, they have to be printed down but without loosing the impression of brilliance. Subjective tone reproduction makes my head spin, but objective tone reproduction makes little sense without it.
    Attached Thumbnails Attached Thumbnails Jones Graph.jpg   4 quad - Normal.jpg   4 quad - 10 stop LSLR.jpg  
    Last edited by Stephen Benskin; 12-24-2011 at 04:51 AM. Click to view previous post history.

  2. #32
    Stephen Benskin's Avatar
    Join Date
    Jan 2005
    Location
    Los Angeles
    Shooter
    4x5 Format
    Posts
    1,218
    I should have included this in the last post. This is the same 10 stop luminance range, but the negative density range doesn't match the the paper's log exposure range. As Jones has suggested, the NDR is higher than the paper LER. The resulting mid-tone gradient on the tone reproduction curve is over the 1.10 minimum for a perceived quality print. If needed the highlights and shadows can be controlled through printing techniques.

    To me, this appears to support Michael's observations. In addition, it is consistent with tone reproduction theory. Tone Reproduction Theory - it's a problem solving tool.

  3. #33
    CPorter's Avatar
    Join Date
    Feb 2004
    Location
    West KY
    Shooter
    4x5 Format
    Posts
    1,662
    Images
    24
    Quote Originally Posted by Stephen Benskin View Post
    I assume the step tablet is in contact with the film. If so, then it is a non flare test.
    So, by this reasoning, if there is no step tablet, then the original testing can be considered to include flare and it then becomes a question of how much based on the target in question.
    Last edited by CPorter; 12-24-2011 at 10:10 AM. Click to view previous post history.

  4. #34
    Stephen Benskin's Avatar
    Join Date
    Jan 2005
    Location
    Los Angeles
    Shooter
    4x5 Format
    Posts
    1,218
    Quote Originally Posted by CPorter View Post
    So, by this reasoning, if there is no step tablet, then the test can be considered to include flare and it then becomes a question of how much based on the target in question.
    If the target has a full range, and it also depends how it is shot. Look again at the camera/flare Quad example. If you're making the exposure at the metered exposure point, there is little flare no matter what. This would include any situation where a target is metered and then the camera exposure is stopped down. If this is the way the testing is done then there's only a chance flare would go from zero to 3%. That's a long way from 100% at the point of the test. To introduce the appropriate amount of flare, you would need to meter a gray card and then shoot a black card that has the necessary reflectance (4 or 4 1/3 stops darker than the gray card) which does not fill the frame and is surrounded by a sunlit scene. Of course, one reason why flare is problematic in testing is that it is extremely difficult to control and measure.

    If you're interesting in just seeing how flare affects things, you should do the Black Box test that Phil Davis discusses. I suggest surrounding the black box's opening with targets of varying reflectances.
    Last edited by Stephen Benskin; 12-24-2011 at 04:03 PM. Click to view previous post history.

  5. #35
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,272
    Images
    46
    Click image for larger version. 

Name:	two-tone-target.jpg 
Views:	5 
Size:	524.7 KB 
ID:	43373

    This painted plywood two-tone target, specified in Minor White's Zone System, does not have much flare. The two tones are supposed to meter one stop apart - so it is a one-stop Subject Brightness Range.

  6. #36

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,721
    Totally agree with you, Stephen. I should have been more clear in my posts that I don't think NDR_LER methods are wrong or broken, just that further considerations are required, particularly when we encounter subject luminance ranges that are substantially different than "normal". In my work I am very often dealing with extreme subject luminance ranges, and through years of practice I have simply come to realize that if we truly understand densitometry, NRD/LER, we know when and how to bend the rules to achieve the original visualization in the print. If people blindly try to always match the negative and paper, thinking this is the best way to a fine print, I'd say they are just as much in your "do we know what we're getting" zone as people who misinterpret their test data.

    Bill, I don't want to completely derail your thread but in reference to your earlier post I am definitely open to discussing the issue of long luminance range subjects further in this thread. I have some examples I can attach too if it helps anyone. My overall point is that people who automatically apply diluted stand or compensating development to high contrast scenes may be giving up more than they gain - again to Stephen's point: do we know what we're getting?

    Very interesting discussion as usual, guys.

  7. #37
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,272
    Images
    46
    Michael,

    I think it would be fine to expand your idea.


    Maybe I already do that. I know for example, when I place a shadow on Zone II, then spot a caucasian face, I want to "place" that on Zone VI. So when my meter already shows it as Zone VI - I declare that negative N. Even if the sky meters Zone IX. I will let that go, or add a yellow filter to pull it down a bit.

  8. #38
    Stephen Benskin's Avatar
    Join Date
    Jan 2005
    Location
    Los Angeles
    Shooter
    4x5 Format
    Posts
    1,218
    Quote Originally Posted by Michael R 1974 View Post
    If people blindly try to always match the negative and paper, thinking this is the best way to a fine print, I'd say they are just as much in your "do we know what we're getting" zone as people who misinterpret their test data.
    It's almost my mantra. One of the most important aspects of testing and one of the most overlooked is the theory / reason behind the concept. The "why" of something is as important or even more important as the "how."

    Here's wishing everyone a Merry Christmas.

  9. #39
    Stephen Benskin's Avatar
    Join Date
    Jan 2005
    Location
    Los Angeles
    Shooter
    4x5 Format
    Posts
    1,218
    Quote Originally Posted by Stephen Benskin View Post
    That's a long way from 100% at the point of the test.
    Sorry, that should read as "That's a long way from the 100% of additional exposure caused by flare as seen in the shadow exposure."

Page 4 of 4 FirstFirst 1234


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin