Color casts & film base color
I just started processing C41 this week and thus far don't have great results. I'm using the Tetenal kit and for my first few rolls I tried splitting up bleach and fix as another member here recommended. That wasn't working at all. After further reflection I think I was way off on the dilution (started at 1+4, then 1+3, but I believe it should have been 2+3 to be equal halves each of the blix formula). Those early rolls were re-bleached and re-fixed (and a few strips were re-blixed too) and I feel pretty certain that process went to completion. But none of my 35mm rolls (Reala, 400VC, 400H, 800NPZ, Superia 200), including the more recent ones done after I switched to only using blix as per directions, are that bright orange-red color my lab negs are. More of a tan-orange, although perfectly clear. My 120 rolls (400H, 160NC) for some reason are a totally different color (brighter).
Anyway, when scanning I get poor color. Generally a cyan cast. Normally with lab negatives I do very little other than auto-levels or white balance in Vuescan to get a scan that looks good. My self-processed negatives take a lot more work, although they're fixable. In extreme cases I'm unable to fix them accurately, like in the case of my Reala roll. The scans look quite nice, but they simply don't look like Reala to me. Frames that were on the lighter side look like 160S and frames on the darker side look like 160VC, for example.
(The above is about my 35mm scans...have only scanned one of my 120 frames thus far, from the early roll that had to be re-blixed. Cyan cast on that one too but it corrected beautifully).
I've processed 5 rolls of 35mm and 3 rolls of 120 in 1 liter of each chemical. I am re-using chems but I don't think the developer could be exhausted already with such a small number of rolls (I realize I probably shouldn't do many more with this liter though), and besides, the first rolls in fresh developer were giving me the same result.
I'm using just a basic Paterson tank and reels, with a water bath. I don't know if my thermometer is completely accurate when I read it at 100F, it's kind of old. But I've measured just the water alone for up to 15 minutes and not seen any significant drop in temperature, so whatever temperature it is, it's consistent.
I guess I'm just not sure where I'm going wrong. Is it perhaps all down to temperature? Tonight I can upload some uncorrected scans and comparisons of the base color of lab negs vs my negs if that helps.
Sorry so long and rambly, it's just been 3 days in a row of this now and I just wish I knew what was wrong.
Use a digital thermometer you use to measure fever. They are cheap, fast, easy-to-read and usually water-proof and they have to be quite accurate; 100F/37.8C is a typical fever . (I currently have 37.3C due to swine flu ! Not as bad as advertised.)
The water bath can be a tad warmer than the process temperature, as the bottles and tank are not completely submerged and agitation in air brings temperature down. Say, 102 or 103 F.
Measure the actual temperature of the developer before starting, not just the water bath. It takes surprisingly long to heat if you are just using the process waterbath. Use warmer water to make this happen faster, and when it's at 100F, then move it to the actual waterbath and wait a bit to stabilize the temperatures.
But, I don't think that the main problem is in the temperature. What you describe sounds quite bad. Color crossover can be caused by temperature error, and too low temperature indeed causes cyan cast (due to the underdevelopment of the bottom red-sensitive layer), but that is not something you easily see with bare eye when looking at the negative.
I still suspect the blix. Although the Tetenal C-41 blix has worked flawlessly for me and many others, it's said that it's not easy to make proper film blix. And, Tetenal has failed the RA-4 blix also, so I wouldn't be surprised if that was the cause.
Really hard to see what's going on from a distance, without seeing the actual negs. Do you have an colour apugger in your area who can have a look?
I will assume that your chemistry was in good condition; if you have any doubts then you have no choice but to buy fresh and start over. Let me suggest first reviewing your process from the ground up as carefully as possible, and that means knowing the dilutions and temps and all other parameters (including how you pre-clean your tank) very accurately. There just isn't any room for 'pretty sure' in c41 (and e6 is considerably less forgiving, I find). You first of all have to know that the temps and times are bang on and consistent and not varying throughout the process. My first probs with c41 were eventually traced back to temp drift in my tanks. Look, if you are asking whether your temps were wrong then you need to go back to square one and be *sure* that they are right... in the developer. For the whole time required. You'll just frustrate yourself otherwise. c41 is as easy... and as hard!... as making a box cake. Everything has to be pretty much bang on, or you get an inconsistent result.
Next, I would shoot a roll of some film and split it up, taking the same shot of the same subject 24 or 36 times. Pull out snippets of the roll and develop those, and maybe even put the last one through a lab so that you have a good reference. Until you get consistency from snippet to snippet and your results compare roughly to what a lab gives, you can't move on. Know that you will reach that point, but it doesn't happen quite as easily as with straight b&w. It'll take some time to figure out what the most important parameters are... I think they are probably temps and times and how good a job you do cleaning your vessels and transferring chems. Listen, I am certainly no c41 expert, I am just saying what my issues were.
Patience, patience patience... oh and don't start dev'ing really meaningful things until you have the consistency and confidence built up. Nothing more frustrating than being heavily invested in a shot that gets effed up because something was amiss in the processing. Why not shoot a test roll and work on it bit by bit and insist on consistency foremost.
keithwms, you make it sound quite difficult .
I have always used a "take it easy" mentality and still I always have good negs. But, I'm quite careful by nature.
A small deviation in temperature, like 1F, is not critical, but if the deviation for some reason is something like 5 or 10F, then it probably is the culprit.
You can practice with water in tank instead of developer and measure the actual temperature of the water in the beginning, middle and end of the processing time (3 min 15 sec).
Sorry then, it's not, I agree I am just saying... even when I did my first b&w it was difficult because I made a lot mountains out of molehills... and it took a bit of time to sort what is vs. what is not so important. Likewise c41. The big thing with c41 in my experience was temp control. That was a new variable for me, coming from b&w. (and then I did e6 and now I think c41 is easy! :rolleyes: )
Originally Posted by hrst
With c41, at first I didn't realize at first just how different the dev temp and the bath temp could be (duh), and how much temp drift there could be (duh). Now I have a more careful process and everything seems to work better.
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None of the rolls I've developed thus far were "important" per se, but they weren't serious tests either as they'd been shot over a few months under varying conditions (and purposefully used different films because since I'm used to only developing b/w it's intriguing to me that times are all the same in C-41).
hrst, I'll try the water practice as a test, thanks! Water bath is around 110 or so and I do leave the thermometer in the bottle of developer until it has normalized on 100F for a couple minutes (it's the kind with a round dial face and a pin sticking straight down, so I can just leave it propped in there until ready). I think the process of heating/measuring is correct, but it's possible this thermometer is no longer accurate.
Keith, by "temp drift" you simply mean that the tank wasn't truly staying at 100F for the whole 3:15 minutes, right? Are you suggesting to stick the thermometer in between agitations to keep an eye on it? (although once the temperature drops it seems like it's too late to fix, developing time is so short).
I do suspect the times a bit as well, because it's hard to figure out exactly when to start the clock when pouring developer in, and am I supposed to match the very last drop of developer coming out of the tank with the timer beep? And in the few seconds it takes to get the blix poured in, is the film continuing to develop? Maybe it's just my b/w mind thinking but extension of time in this sense seems like it would simply lead to overdeveloping (increased contrast, grain, exposure) but not necessarily color casts.
Anyway, the test of cutting up a roll sounds like a good one...might shoot a cheap one tomorrow morning to play with.
Just to add: in addition to reading here and the manual, I followed instructions from someone on Flickr whose only deviation from my materials is that he uses glass bottles. Everything else he uses is the same--kitchen sink as a water bath, Paterson reels/tank, Tetenal. That's what initially made me believe this would be easy .
I start the clock when I start pouring in the developer and start pouring the developer out 8" before the time is up. It takes me about 15" to get the bleach fully in so there is about a 10" 'error factor' in my changeover. This is normal. Even automated machines have a short delay as the film runs out of one tank into the next. It is accounted for in the process.
As for scanning, here is what I suggest. Scan a frame in as if it were a slide, then we can look at the negative. Scan the same frame as a negative and we see the negative as it should appear as a positive.
This should give us something to work with. I hope that you included a step wedge? This is a great benefit at the early learning stage.
Well, no, you probably don't want to have to look at a thermometer during the 3', but I would first investigate, with lights on, what happens when you bring ordinary water up to temp and then pour it in and out etc. You just have to satisfy yourself that your procedure keeps the right solution temps throughout. By the way, I use stainless vessels and noted that when pouring my solution into a cold vessel, the temp dropped appreciably. So I preheated my vessel, problem solved. I also saw appreciable temp drift when tray dev'ing c41 LF film, even with a temp-controlled 'bain'... something I am still working on. For e6 its more critical, I need to install a temp controller with a thermometer directly in the developer.
Originally Posted by naugastyle
I like Ron's suggestion to scan your negs as positives... experts can diagnose many ills that way.
I am pre-heating my tank but I realize plastic probably doesn't hold the heat well...I suppose I was counting on 3:15 (or 3:30) as not being that long for the heat to need to hold.
I'm feeling a bit like I over-panicked. Perhaps it was the blix after all, because I just scanned some of the new negs from last night (after I mixed blix correctly instead of trying my separated version) and the problem is not nearly as pronounced as before.
Well then, maybe there's no problem at all! Post some shots for us!