Room temperature stand development -- for C-41?!

pentaxuser

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I think the most obvious source of colour crossover, in fact from what I can see the only colour crossover is the way the front surface moves gradually from a magenta-like colour to a dark beige colour. How big the difference is seems to depend on whose scan it is. It is even more noticeable in Stephe's scan than Donald's.

Donald, can we take it that there is no such real change in the surface colour in which the objects stand? By that I mean that nothing within the lighting set up is casting a kind of a magenta shadow there that slowly disappears as we move towards the back of the surface?

It has always struck me that one of the strengths and at the same time weaknesses of scanning is its ability to correct a "fault" that was not a fault in the first place such that the "crossover" would be seen by the naked eye. It may not be as clear to the naked eye but a colour measuring instrument would detect it. I hope I have explained that well enough to make what I am saying make sense

I think I am getting back in a way to the late Roger Hicks' "Yeti" photo. He had taken a picture of a white cat called Yeti in the U.S. that when he developed it had a faint pink tinge in a certain part of its fur. Convinced the cat was pure white he tried to correct the "fault" on RA4 and when he had managed to or nearly so, other colours had been been give a false cast. Try as he might he could not get a correct RA4 print

He had concluded that something had gone wrong with the negative until he returned to the U.S., had seen the cat again and realised on close examination that the cat did indeed have a very faint pink tinge to certain parts of its otherwise pure white fur.

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StepheKoontz

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I just tried my inversion process using a sample from the rebate of the normal processed negative, it didn't help. My understanding is the mask is not a global color, but is proportional to exposure, and is why simply using color balance tools to remove it don't work. I'm not a chemistry/film expert, but what appears to be happening is some colors develop at different rates than others, so over or under development causes color shifts.
 

StepheKoontz

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I just tried my inversion process using a sample from the rebate of the normal processed negative, it didn't help. My understanding is the mask is not a global color, but is proportional to exposure, and is why simply using color balance tools to remove it don't work. I'm not a chemistry/film expert, but what appears to be happening is some colors develop at different rates than others, so over or under development causes color shifts.
 
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Donald Qualls

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That's approximately what I said about the imagewise density of the mask. I also agree that my understanding of crossover is that it's a result of the color layers developing to different contrast levels than what's compensated by the mask.

I've seen that some kits have times for lower temperatures, even one as low as 20C -- but if the stand process is producing crossover, I'd expect that a time compensated lower temperature process with normal agitation is likely to do so as well (though perhaps to a lesser degree). Whether the degree can be lessened to the point of producing acceptable prints is another question. The image I posted earlier (of the Sheetz Brothers coffee sign) doesn't have it enough for my eye to pick out, but that was a pretty "non-normal" exposure in several ways...
 

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I got streaking when developing 4x5" negative film (well, only with Ektar) in my Jobo drum at 38ºC, so I wanted to know what would the results be at lower temps (where I got no streaking) compared to standard processing. First I did it at 30ºC (8min). I didn't like that the shift was quite big so I didn't try even lower temps. At the time I decided that I'd rather shoot Portra 160 than compromise the results. Although I believe I could match the scans in post-processing, I always feared that negatives would have problems with wet printing. Now that I finally can do RA-4 prints I might try to print a pair of negatives and see what I get.

Anyway, here are both strips (developed at 38ºC and 30ºC) that were scanned side by side on a Epson 4990 flatbed with quick invert to get a reasonable results from 38ºC negative:



A pair of those scanned on a Minolta 5400 with the same inversion for both:




200% crop to show the grain:


 
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Donald Qualls

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Those negative strips look as if the 30 degree set got a little less total development -- that is, time compensation might have been insufficient. That might then account for the color shift.
 

pentaxuser

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Well there is a slight but distinct magenta cast in the 30C negs compared to the 38C but as the slight cast seems to be uniform, it begs the question of whether in optical exposure and RA4 printing this might be easily corrected?

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brbo

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Finally had the time to print and scan. Those two are from the same two rolls that the examples in my previous post are from, Fuji Color 200 shot side-by-side.

I didn't spend any time on the 38º print, just to get a reasonable balance and then tried to match that with a 30º negative. As you can see there is a cross-over and you can't match both, light and dark, parts of the image.

 
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brbo

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Yes. We've seen here negatives with "alternative" processing that look far worse and people still claiming they work perfectly for them.
 
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Donald Qualls

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I see a 1/3 to 2/3 speed loss in the 30C negative, relative to the 38C -- but I see a green shift, rather than a crossover, in the 30C (I don't see crossover well for some reason, even when I'm specifically looking for it).

Bottom line, for me, is if I'll only be scanning and my schedule works better with stand processing at room temp (usually 16-18C in my darkroom, at least when the A/C is in use), I'll consider room temperature stand processing for test rolls and such -- but it's easy enough to get correct temperature that I'll treat that as a "special case" and do my regular negatives (like the ones I shot today, with fall colors on the trees) the regular way.
 
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Donald Qualls

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koraks said:
Yeah, I agree, and that sort of makes the while matter moot for me. Still, I find these experiments quite valuable.
Click to expand...

Oh, yes. I had to try it just to see how well it did or didn't work. At no point did I risk potentially important images -- a camera test roll and then one shot specifically for the process test.

Even with canonical temperature control, I still say C-41 is easier, in some ways, than B&W processing. Always one set of chemicals, one temperature, one time, regardless of the film used. No questions about "is developer X a good match for film Y?" No hundreds of possible combination, even without factoring in time/temp variations, agitation method, user's water, phase of the moon... (well, okay, user's water can factor in with C-41, if they mix their chemicals with tap water rather than DI or distilled).
 

pentaxuser

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koraks said:
That's still pretty close. There is a difference for sure, but I bet many people would find it acceptable.
Click to expand...
So close in fact that even when I scroll up and down to each in turn to compare I cannot see what the difference is. If someone can point to the appropriate part or parts of the two that demonstrate the crossover I'd be grateful

Thanks

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MattKing

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pentaxuser said:
So close in fact that even when I scroll up and down to each in turn to compare I cannot see what the difference is. If someone can point to the appropriate part or parts of the two that demonstrate the crossover I'd be grateful

Thanks

pentaxuser
Click to expand...
It isn't a great subject for revealing crossover - human skin is better.
I see a crossover shift in the 30C example - you look at both the sidewalk and the ceiling above it as your eye moves from the fully illuminated area at the front to the shadowed area near the door - there is a subtle shift toward the green.
 

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Thank you!
 

brbo

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MattKing said:
It isn't a great subject for revealing crossover - human skin is better.
Click to expand...

I thought it was a perfect example (well, from the ones I could pick from, obviously). It's got a transition from light to dark part and the pavement is generally a close proximate to neutral grey and so a known starting point. I don't know how a certain single hue could reveal any crossover. I think that for an evenly lit portrait shot you could probably balance the filtration for skin alone and get away with it even with a negative that was far more out of the specs than what I have here with 30ºC processing.

But, ok, let's try this (this is as much skin I have on that roll). The lighting is poor and Fuji C200 is far from the best choice for skin tone. Both are balanced for a general feel (and I didn't do more than two test prints) and not for same skin tone, I could probably match the skin tone in both and then we would be again looking for any evidence of crossover in dark and light parts of the image and not in skin tones.

 

pentaxuser

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Thanks,both of these look as identical enough to me as not to matter but what isn't clear is what if anything did you have to do in one of the scans to make it identical in the other i.e. did you alter or is it even possible to alter one part of a scan to alter one part of the picture to correct a problem which is not possible with optical enlargement.

In an optical setting if you alter the filtration to correct an imbalance in say the skin in this particular picture I'd assume that this would be seen elsewhere in the colours but here while the skin in the 30C pic originally looked slightly magenta now it does not but nothing else seems to have changed.

Could we expect a slight change in optical filtration to do this without altering the rest?

My instinct says yes this is possible based on small magenta corrections I have made with an enlarger which did remove a slight magenta cast without adverse;y affecting anything else. If I am right then there would appear to be no colour crossover here - not that I noticed any signs of this anyway. There was simply the requirement to make a slight correction to the slight magenta cast in the 30C.

If this is genuinely the case then your experience suggests that 30C is not a problem at all

pentaxuser

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brbo

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Not sure I understand the question.

My post #79 contains scans of the negatives. The 30ºC images have a strong magenta cast because they were inverted exactly the same as the 38ºC (think of it like optically printing both negatives with the same filtration and the filtration based on 38ºC negative).

Posts #82 and #91 are scans of optical prints. Both negatives, 30ºC and 38ºC, exposed subsequently on the same sheet of paper (I use different exposure times and filtration to match them) so they get exactly the same processing.

What I gather from this exercise is that 30ºC negatives go slightly green in shadows where 38ºC stays more or less neutral - crossover. Of course, maybe going slightly green might be preferable to some or even more to the specs. I have never processed control strips to actually verify that my C-41 process at 38ºC is actually good.
 

pentaxuser

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Thanks brbo I had not noticed that on #91 these were scans of optical prints but if I had read your post more slowly then this was clear. I am never sure when I see scans of negatives inverted to positives if they fully represent what I would see if it was a RA4 print.

So it now definitely looks to me that the slight magenta cast in the 30C processed negative can be corrected in optical printing as you have done. If skin tones are best at revealing colour crossover then as far as I can see there is no crossover there.

Yes there may be the slightest sign of a change to a greenish shadow in the shop doorway in the 30C example but I wonder if I now see something that I think is there because others have seen it. Koraks statement in # 83 sums things up for me

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brbo said:
I thought it was a perfect example (well, from the ones I could pick from, obviously). It's got a transition from light to dark part and the pavement is generally a close proximate to neutral grey and so a known starting point.
Click to expand...
The transition was perfect, but pavement often surprises one with slight traces of variations in colour that are somewhat unexpected.
But I do appreciate what you are doing.
There is a small bit of crossover in the 30C version of the people pictures - more of a cyan cast in the highlighted background when the skin tones are well balanced - but you only see it clearly if you pull the digital image into an editor and increase the saturation.
All in all it is a very interesting demonstration.
brbo said:
I think that for an evenly lit portrait shot you could probably balance the filtration for skin alone and get away with it even with a negative that was far more out of the specs than what I have here with 30ºC processing.
Click to expand...
For test purposes, a more traditional type of portrait lighting, with more three dimensional modeling and more transition from highlight to shadow, would provide more of a test.
 
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Donald Qualls

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MattKing said:
For test purposes, a more traditional type of portrait lighting, with more three dimensional modeling and more transition from highlight to shadow, would provide more of a test.
Click to expand...

So, what we're saying here is that there's a process temperature above which only a masterwork will have enough color problems to matter? And that temperature may be at or near 30C?
 

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Donald Qualls said:
So, what we're saying here is that there's a process temperature above which only a masterwork will have enough color problems to matter? And that temperature may be at or near 30C?
Click to expand...
No - just that the sort of flat lighting that is commonly used for portraits nowadays may not show as much as older styles of portrait lighting or other more contrasty lighting styles.
Like flash illuminated birthday parties .
 

brbo

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Donald Qualls said:
So, what we're saying here is that there's a process temperature above which only a masterwork will have enough color problems to matter? And that temperature may be at or near 30C?
Click to expand...

This example supports no such deduction. Remember, this is only one emulsion, one format, one point in "life" of my C-41 chemistry (I don't use it one-shot). I wouldn't be surprised if other emulsions or formats would have different problems/no problems at all, of greater/lesser degree...
 

Nicolas G

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Hi!
I apply a stand development C41 at room temperature on all my colour films for 2 years. I did it on a various type of 135 and 120 films and also on slide film in xprocess. I use the usual dilution, 1h dev, 45min blix, 4 washes and 2min stab
You can see the results on my Instagram @filmphotographybynico
I don’t do that for a better result, I do it because it is more convenient for me
 
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