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  1. #1

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    Okay, don't just start jumpinig all over me on this one. BUT, I read a lot about the crucial nature of color (and black and white) chemistry temperature before I started trying to incorporate color into my lab. The way I re-designed the lab however, temperature is the hardest aspect to maintain at this point. Before I went out to get solutions to this problem, I did some tests. I should at this point mention that I use only Agfa professional chemistry unless they simple don't have it (like R3) because I read that it is more forgiving at lower temps. Anyway I found that so long as I was aware of the temperature, the times could be adjusted upward to compensate. This maintained nicely until the temp dropped below 70-75 F.

    HOWEVER, I am not a photographer so I have always wondered if my testing was really valid. In other words do I really know what to look for when I looking for the discrepancies. I would like to see an explanation or list of what I should be eagle eyeing when doing these tests from people whose standards I would imagine are quite high.
    Embrace **it! **it. . .just another name for fertilizer. . . Grow baby Grow!

  2. #2
    Aggie's Avatar
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  3. #3

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    I'm not in NY I am in boise, ID. (big pout) I'll check my profile and see what I screwed up.
    Embrace **it! **it. . .just another name for fertilizer. . . Grow baby Grow!

  4. #4

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    In response to your question, as it applies to black and white processing of negatives designed for enlargement, the determiner of the proper time/temperature correlation would be the density of the highlights in the negative. This would ultimately determine whether the negative would print with a full tonal range. (This assumes that the photographer is exposing the scene to gain adequate shadow detail and is cognizant of the desired development of the negative).

    Typically, the contrast range of a properly exposed and developed negative would be on the order of 1.20-1.30 (above FB+fog) for a negative designed for enlarging with a diffuse light source and on the order of 1.10-1.20 (above FB+fog) for a negative designed for enlarging with a condensor or point light source. The means by which one reaches that density contrast range by whatever variable of time and temperature is immaterial.
    Art is a step from what is obvious and well-known toward what is arcane and concealed.

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  5. #5

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Darkroom ChromaCrafts @ May 4 2003, 05:54 PM)</td></tr><tr><td id='QUOTE'>HOWEVER, I am not a photographer so I have always wondered if my testing was really valid.&nbsp; In other words do I really know what to look for when I looking for the discrepancies.&nbsp; I would like to see an explanation or list of what I should be eagle eyeing when doing these tests from people whose standards I would imagine are quite high.</td></tr></table><span class='postcolor'>
    Jill,

    I agree that AGFA chemicals (industrial grades are not that different from the professional/amateuer versions) are less critical in delivering good results. However, the best way to keep track of the processes are still control stips. You&#39;ll need a color densitometer and process control stips to keep track of your processes. You may find older Color Densitometers, like the Mcbeth TDxxx-Series, on Ebay for a bargain. AGFA (Kodak and Fuji as well) has a book with detailed instructions what might be the cause for which deviations from the set points.

    I did not understood, what your problem with temperature acutally is/was.

  6. #6

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    As far as I know I don&#39;t have a problem, but as I head from aerial photography, in which photographic perfection is simply not required, to printing and reproducing for artists and professionals; I thought it might be wise to find out if I am really looking at the results with the right concepts and concerns in my head and eyes.
    Embrace **it! **it. . .just another name for fertilizer. . . Grow baby Grow!

  7. #7

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (dnmilikan @ May 4 2003, 10:48 AM)</td></tr><tr><td id='QUOTE'> In response to your question, as it applies to black and white processing of negatives designed for enlargement, the determiner of the proper time/temperature correlation would be the density of the highlights in the negative. This would ultimately determine whether the negative would print with a full tonal range. (This assumes that the photographer is exposing the scene to gain adequate shadow detail and is cognizant of the desired development of the negative).

    Typically, the contrast range of a properly exposed and developed negative would be on the order of 1.20-1.30 (above FB+fog) for a negative designed for enlarging with a diffuse light source and on the order of 1.10-1.20 (above FB+fog) for a negative designed for enlarging with a condensor or point light source. The means by which one reaches that density contrast range by whatever variable of time and temperature is immaterial. </td></tr></table><span class='postcolor'>
    I appreciate your response. I was hoping the end results would be the determining factor, but I was concerned if the cooler chemistry would actually fail to perform in a manor that might not be noticable right off but would age badly. I am gathering the answer is no, for b&w film and negatives.

    I am afraid I am at a complete loss at to the FB+fog and so on, but I&#39;ll get hopping. I bet I can find some article or book somewhere that explains it to me, so next time I will understand better.
    Embrace **it! **it. . .just another name for fertilizer. . . Grow baby Grow!

  8. #8
    David A. Goldfarb's Avatar
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    What Donald is saying is that if you aren&#39;t consistent about time and temperature, particularly of the developer, you won&#39;t get a consistent level of contrast in your film or prints.

    Furthermore, with the right testing, you can control contrast in a creative way, because not all lighting conditions create the same level of contrast, and not all reflective objects in the world will be rendered with the same degree of contrast on film. In color work, you might also get color shifts.

    For a basic understanding of how this works, read Ansel Adams&#39; _The Negative_ and _The Print_. Adams is writing about B&W, but the principles can be applied to color as well, with the additional variable of color balance taken into account.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
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  9. #9
    lee
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    Jill,
    Donald is talking about film base+fog. That is the clear or nearly clear part of the negs. You need a densitometer to read it. Basic zone system talk. IF you minus out the fb+f then the density that is at zone VIII should be 1.2 to 1.3. That is a good development time for enlargements with diffusion heads. Typically, cold lights and color heads are diffusion type heads. NOt everyone uses these heads. For some reason, the others prefer condenser heads. The zone VIII density will have to be lower to compensate for some weirdness that condensers cause. It ain&#39;t too hard but not coming from a photo background, you will have to swim upstream for a while as fast as you can.

    BTW, is 133 lpi enough screen for your artists? Are they doing their own printing? Are these negs used for plate making and then the plates are hung on your offset presses? Inquiring minds want to know.

    lee&#092;c

  10. #10
    Ed Sukach's Avatar
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    I, for one, firmly believe that there is a good deal more latitude in temperature than is commonly thought.
    Being deft as all get out, and *never* making mistakes (believe that one and I&#39;ve got a bunch of aluminum siding I&#39;d like to sell...), I won&#39;t reveal my sources ... but...

    Color negative film is commonly developed at 38 degrees Celcius; color paper at 35 degrees Celcius. Using a JOBO processor, the temperature is set using three dials.
    It is supposed to be a *great* mistake to deviate by more than ... what? ... one-quarter of a degree, in either circumstance. I&#39;ve forgotten ... uh ... well *someone* - once forgot to change the temperature, processing C41 film in the color developer for the prescribed 3 minutes, 15 seconds at (gasp&#33 35 degrees Celcius. Wonder of wonders&#33;&#33; *NO* explosion, and the color balance and density wasn&#39;t "off" more that what could be randomly expected.
    Paper development has also been done, in error, at 38 degrees Celcius with equal results. Processing is never completely without variables... and these differences - note: three (3) degrees Celcius - did not appear to be terribly disastrous.

    You CAN use "temperature tolerant" chemicals - JOBO/ Tetenal RT is one example. I&#39;ve never used it ... I&#39;ve never found the need to use them.

    I&#39;ve even had the telephone ring during processing color paper, and for one reason or another, LOST track of the time - as much as 100 percent time increase - One minute, thirty seconds, instead of the prescribed 45 seconds. No significant difference that I could see ... and I consider myself to be as much of a picky perfectionist as the next guy.

    My theory is that the manufacturers of film, paper, and chemicals used in "small lab" work use "strict tempertaure control" as a sort of safety valve, so that *any* unexplained results can be attributed to "improper temperatue control".

    I&#39;ll advise: Give it a try ... ypou don&#39;t have a great deal to lose (relatively - after all this is photography). I&#39;d be willing to bet you&#39;ll do well.

    All that said ... WELCOME to APUG. *I* checked, and understood that you were in Boise, Idaho.

    *How* big are those prints??&#33;&#33;
    Carpe erratum!!

    Ed Sukach, FFP.

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