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  1. #1

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    Room temperature C41

    I've been processing color film at home with some success. I'd modified an aquarium heater and could consistently get 100deg but it was a pain in the ass and took alot of time. I've recently been working with the Rolli kit from freestyle, it has separate bleach/fix so it has an additional step over the Unicolor kit, adding to the time. Interestingly the directions indicate it can be used at less than 100deg so I decided to see how it'd do at room temperature. The first three images are Kodak Portra 160 (4x5) at 68f for 16min, 18min and 20min. I'd planned 22min as well but blew the development on that one. The last image is from a roll of Fujicolor Pro 400, 120 film, developed at 68f for 21min, 20sec agitation initially then 4 inversions every minute; bleach for 7min then fix for 8, same agitation routine. Also, rinse with water before and between each step, mostly to reduce contamination of the chemicals.

    It looks promising. I've ordered a couple more Unicolor kits to see if it will work as well. I also want to try it with Ektacolor 100.

    p.s. I see the attachments were re-ordered somewhat. img358 is 16min, img359 is 18min and img360 is 20min. Thanks.
    Attached Thumbnails Attached Thumbnails img360.jpg   img359.jpg   img358.jpg   img369.jpg  

  2. #2
    georgegrosu's Avatar
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    bobmercier, depends what level of results you are intended to get.
    The instruction manual for use of Rollei/Compard C-41 Color Film Processing Kit - PROCESSING is written:
    This general information is based on intensive tests and experiences of many users of the DIGIBASE C-41 chemistry, who have reported their results and have given allowance for publishing. No responsibility is accepted for the correctness of this information.
    http://www.freestylephoto.biz/pdf/pr...structions.pdf
    If you want to test, you should use a gray scale - at least.
    It gives you information about the contrast, color balance, ....
    Developed a test and a laboratory.
    George

  3. #3
    spacer's Avatar
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    Well, the images came out pretty sharp. The color ain't perfect, but at least the universe didn't implode when you soaked 'em at 68F. That's a good sign.

    Then again, maybe Mario is a bit faded in real life...

  4. #4
    Athiril's Avatar
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    Want consistent temp for normal C-41? Use a plastic tank, pre-soak with ~45c water, agitate, it'll drop down a bit, tank and film will be around right temp, heat up dev to right temp, process away for 3m 15s.

    dMax-dMin suffers I've found at low temp.

  5. #5
    Rudeofus's Avatar
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    While I would love room temperature processing, I am afraid that room temperature varies way too much for repeatable results. In winter it easily falls to 20°C (why waste a fortune on room heating?), while in summer 30°C or more are not rare, even at night. With a bucket of hot water I think it's a lot easier to get 38°C right than anything between 20° and 30°C.
    Trying to be the best of whatever I am, even if what I am is no good.

  6. #6
    georgegrosu's Avatar
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    I see this test as a way to reduce negative image contrast in color. The difference in contrast between the developed image from 16 min to the 18 min is notable. You should see the loss of sensitivity of the film, possibly to correct the shooting.
    I think it is better to test the 2-3 types of films. Not all films respond equally to such processing.
    In the processing to 37.8 ° C the color negatives should not be something that scares you. Work with a plastic tank and a sink for thermostat.
    I put developer in a plastic tank, make the temperature and put the film from the black bag . In three minutes and something the developer temperature will vary not more than 0.1 - 0.2 ° C.
    Better not do Pre-Soaking.
    Intermediate washings are beneficial.
    George

  7. #7
    Lee L's Avatar
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    Rather than judging the comparison from the posted images immediately, my first reaction is to ask if the scans were identical, with the scanning settings for color balance and contrast locked in, on which image they were locked, and also to ask how the OP's system is color calibrated, if at all. It would be nice to know about the scanning method and consistency there before attributing all the variations to the developing. I know we're not supposed to discuss scanning per se, but in this case it's critically important to judging the results of a test.

    Lee

    P.S. Looks like it was an Epson flatbed scanner, as the images have an Epson standard RGB profile with gamma 1.8, which might explain some of the reduced contrast noted by George.
    Last edited by Lee L; 07-11-2011 at 07:44 AM. Click to view previous post history.

  8. #8
    Greg Davis's Avatar
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    Somewhere is a test I conducted and posted here showing the differences in Ektar 100 when processed at 68, 77, 85, and 100 degrees, as well as a shot processed in a pro lab under tight controls. The results were not good for any but the 100 degree shot. Photoshop was needed to correct for lack of contrast and color shifts, as I had maxed out my enlarger for color correction. My conclusion was that the cooler temperatures are OK if you are intending on scanning the film and correcting in the computer, but for darkroom work, 100 degree development is needed to get the proper color balance
    www.gregorytdavis.com

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  9. #9

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    I'd love to see this done with control strips and densitometer measurements. On page 5-29 of Z-131, there's a chart showing the effect of low temperature on the various densities. at -4F from aim, there is a significant decrease in Dmax and Hd-Ld:

    Note that the densities decreases differently, based on layer order and the diffusion rate through each. While I imagine one could correct for some of the color balance change, there comes a point where I think you're approaching SOL.

  10. #10
    Lee L's Avatar
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    Quote Originally Posted by epatsellis View Post
    Note that the densities decrease differently, based on layer order and the diffusion rate through each. While I imagine one could correct for some of the color balance change, there comes a point where I think you're approaching SOL.
    In other words, color crossover, which is correctable in software (and which an automatic scan with color correction will mask to varying degrees), but which is difficult or impossible to overcome when printing the neg directly to enlarging paper with conventional analog methods. You can't dial one one color correction into the shadows and a different color correction into the highlights with an analog enlarger.

    Lee

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