Tetenal Color Casts

[hguzzo]

I have been consistently getting varying degrees of a red cast on my negatives (cyan cast when scanned) even when freshly mixed. I’m using tetenal in a combi-plan and kodak 400 nc. I am following the given times except for a longer wash, and don’t think it’s a temperature issue. Could this be fixed through a longer blix? I am also processing up to 12 sheets at a time, has anyone had issues with processing more than 6 sheets of 4x5 in a combi-plan?

Thanks!

 

[holmburgers]

Stupid question, but it's not the orange cast typical of negatives is it? In which case, it could be your scanning workflow.

Sorry, had to ask, cause someone else would've

Hope someone with a little more experience in C-41 can help you out. Welcome to APUG by the way!

 

[hguzzo]

no, its not the orange cast, definitely red when compared to normal color negs

 

[Athiril]

What temp? Tetenal worked great at both normal temp and also 30-31c for ~8 minutes. No probs.

Also may want to check the pH of the developer, it may be incorrect, thats said to cause that problem as well.

 

[2F/2F]

Did you not have this problem with the same film scanned in the same scanner with the same settings using Kodak chemistry? Have you made optical prints at a known-good filter pack for this film, or used a densitometer to compare Kodak C-41 vs. Tetenal C-41 clone negatives? Is the cast correctable?

 

[hguzzo]

I'm developing it at 38c for 3 1/2 minutes.. blix for 6 1/2.

I didn't have the problem using the scanner before, with negatives processed at a local lab- it's really just the last two tetenal kits. Maybe something wrong with the mixing?

The cast is correctable, I haven't made optical prints, but I have made lambda prints that look good.

 

[2F/2F]

I'd try one more experiment. Try using the recommended wash times and see what happens. It is possible that extended wash times can tinker with color balance (though this probably is not an issue in a blix process, as the film has already been bleached and fixed by the time it is first washed). Also, any time I was forced to use a blix instead of the proper two bath process, I would double the recommended time, and I would use up the chemicals as quickly as possible. Mixing bleach and fix into blix both dilutes each by the volume of the other, and speeds up degradation of the solution. To compensate the dilution, you can double the time. In the proper C-41 process, the film is in each of those chemicals for 6:30, so I would blix for at least 13:00. Better yet, just use the proper process with separate chemicals.

At least the cast is correctable. But you really need a densitometer or some sort of "standard" reference point to judge the negatives themselves, with all the variables that scanning and computer manipulating can introduce.

This is really discussion for Hybrid Photo dot org, but I will briefly mention that you should double check your scanner settings and make sure it is set up to scan "color negatives" specifically, not just "negatives." This will compensate for the orange mask and tell the scanner that the contrast of your film will be much lower than with a b/w negative. In the past, when I have forgot to do this, I have had the same results as you.

 

[anikin]

If the cast is correctable by setting a gray point, then everything is fine. You are using different chemistry than the minilab, your
temperature/agitation is different, etc. Print film by definition has no color cast, since you have to correct it during printing/scanning. However, if you have to use curves to correct the color cast, then you are seeing cross-over issues and that's a real problem. Cross over is usually caused by wrong temperature or problems with the chemistry.

Eugene.

 

[2F/2F]

Print film by definition has no color cast, since you have to correct it during printing/scanning.

It is true that differences in processes can cause differences in color casts on films. However, print film certainly takes on color casts, as do all color materials. How could they not, unless a magical color correction technology was built into the film? Whatever color cast the print has when it is made at the normal filter pack for the film/paper/RA chemical combination at hand comes from a cast on the negative. Color negatives get the same casts that color positives do. It is just that the casts on negative film are usually not seen directly by the shooter, as they are on transparencies.

Additionally, using curves to digitally change color balance does not mean that one has crossovers. Using curves is the same basic thing as twisting the filter knobs of your enlarger head or setting a grey point digitally. The difference is that curves manipulation is a much finer control, as it also lets you control to which extent the color alteration affects which areas of the tonal range. Crossovers are what you get when color is simply uncorrectable throughout the image because, in effect, the wrong layers have been given density by a certain color of light. I do not mean to discuss digital so much, but the idea that using curves to correct color means that you have crossovers will send the OP down a frustrating road.

 

[hguzzo]

thanks, next time i will double the blix. i don't have access to a densitometer, but since it it correctable maybe it's not as big of an issue as i thought.. also i didn't take into consideration the differences in chemistry (tetenal vs mini lab)