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  1. #11
    Greg Davis's Avatar
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    Here is a link to my test of different temperatures and times as published by Rollei for their C-41 kit.
    http://www.apug.org/forums/forum40/7...c-41-a-15.html

    Scroll near the bottom of the page for the post and images.
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  2. #12
    David Lyga's Avatar
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    The colors, Greg, are exceptionally pure. My only problem (splitting hairs here) might be the slightly magenta ground on the photo of the lower tree's bark. This, despite the purity of the green leaves. But the overall purity of the hues is (I do hate to have to say this) like with digital. Excellent. - David Lyga

  3. #13
    Greg Davis's Avatar
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    Only the images of me holding the gray cards were done at differing temperatures. The others were a comparison of the two brands of developers at 100 degrees. Here is the same test performed, this was the original, but for proper testing I always run it twice to verify results. I previously posted the second test. Here is the first. They are labelled as "lab", "100", "77", and "68" referring to whether I processed them at what temperature, or they are from a lab of known quality.
    Attached Thumbnails Attached Thumbnails 100.jpg   lab.jpg   77.jpg   68.jpg  
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  4. #14
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    The neutral scale drops off from left to right, 1&2 being about equal and the others being off. Also saturation is low in 3 and 4.

    As expected!

    PE

  5. #15
    hrst's Avatar
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    Yes, indeed if you look at the greyscale, there's a huge crossover. It's clearly visible in the thumbnails.

    And actually, if you compensate the loss of saturation by adding some digitally, the crossover becomes very evident.

    But now, is this crossover visible in real pictures with no grayscale? It depends. In some cases, it may make the image worse, sometimes it will make it better. Or most likely, it won't matter.

    It's still worth noticing that the one processed at 77 F would be quite usable (at least for me), even with a whopping temperature error of 23 F. So, we can probably deduce that error in the range of 5F or so are near to perfect. C-41 is quite robust. (But for right contrast, you have to manually compensate the development time, so what's the point processing a few degrees off on purpose?)

    And, if you want to lower a saturation of a given film, processing at really low temperatures might do the trick easily, if the crossover is not a problem.

    But I suppose David has not really understood how nitpicks some analog photographers really are. They really can tweak some 0.01 density error for YEARS and yes they really can see it! Most of them are B&W zone system maniacs, but it's good to remember that everyone has their own standards and very different threshold for seeing "errors".

    But indeed, it is very useful information that these processes can take enormous amount of mistreatment and still produce images many if not most people are completely satisfied with.

    BTW, I just made 21 contact sheets with a RA-4 developer mixed 1,5 years ago; now, the fun point is that the unopened, factory sealed concentrates of the very same batch have already gone bad, but the mixed developer is perfectly fine. The blix mixed at the same time was fine too. Which is fun, because Tetenal's blix didn't make it even after that 9 months from the factory to me.
    Last edited by hrst; 04-19-2012 at 07:07 PM. Click to view previous post history.

  6. #16
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    HRST;

    This is a mixed bag. For example, Kodachrome had a lot of crossover, but that is what most claimed as its most redeeming feature. I have problems with the examples above, as I have run those same experiments and find the crossover bad.

    In any event, I always say "Use what works for you"

    Do you GROK that?

    PE.

  7. #17
    hrst's Avatar
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    Yes I GROK, thanks for teaching me a new word .

    Reversal RA-4 always seems to give heavy crossover with magenta highlights and green shadows, but in some images, it's a funny signature effect of that process.

    And all slide films have crossover, which is one of the very reasons people want to use them. They give imaginary, fantasy-like colors instead of capturing the reality.

    However, as fun as experimenting is, it is still really important that we have those reliable, neutral and linear baseline standard films and a good process for them; namely the C-41, and I understand very well that you as a creator of those products want to defend this process and how accurate it really is. It is very much taken granted by those APUGers who do their own C-41 and RA-4; whereas those who relied on poor machine prints scream about slide film being the accurate one .

  8. #18
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    Slide films are indeed inaccurate but garish!

    Thanks for understanding.

    PE

  9. #19

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    Now I have seen these four thumbnails, I'd have to say that in terms of the actual look of the shots David Lyga has a point, backed by the Greg Davis thumbnails. I can see very little wrong with the 68F neg.

    Yes in comparison with the 100F neg the colour chart has flaws but unless these showed up in the print colour and no sign of that here then most members of Joe Public would be happy with these.

    I had expected to see bigger problems than this at 68F. If I had no processor but wanted to try C41 at room temp then these shots would encourage me to have a go.

    pentaxuser

  10. #20
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    Don't forget that most scanner software has routines to correct problems. You don't have this when optical printing and therefore you may get (probably will get) inferior results which may require many retries to get near where you want.

    The scanner set the gray, but your first print will be way off for balance. And, there is little you can do for contrast when optical printing except by using draconian methods.

    The devil is in the details.

    PE

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