Why is there color crossover in divided C-41?

Athiril · Feb 20, 2013

One other thing with divided colour developers I've noticed when playing around to see what controls I had over the image:

I used a very minimal amount of KOH for Bath B instead of the several decagrams of carbonate the usual recipes specify.

I did indeed get colour images, pH was indeed sufficient and didn't drop. The definition was terrible.. I don't even mean sharpness. There was like no gradation of colour across objects.

Rather than just pH - the amount of base used needs to be sufficient as well it appears. Though someone said hydroxide bases are not good for colour?

Photo Engineer · Feb 20, 2013

Dan;

Try Tri Sodium Phosphate at high concentration as bath B. That might work better. But, It will not come close to the real color developer.

PE

Athiril · Feb 21, 2013

Okay I finally went to play around with another split bath out of curiousity.

Image (quick colour balance), the sharpness and grain are pretty good for this film (made in Japan Agfa Vista 400)

Bath A
Pinch of Sodium Sulphite
CD-2 – 9g/L
Sodium Sulphite – 9.6g/L
Sodium Bisulphite – 0.54g/L

Measured pH 7.1

Bath B
Potassium Carbonate – 50g/L
Potassium Iodide – 1.4mg/L
Sodium Thiocyanate – 220mg/L (I’m sure my thiocyanate needs drying out too btw).

Detail crop

Out of focus grain crop

Photo Engineer · Feb 21, 2013

Unfortunately, we have no real color patches or other colors for comparison and so we do not have a clear idea of there being any errors in rendition of color.

Sorry Dan. Put a color chart and/or flesh tones and greens in the photo.

PE

Athiril · Feb 21, 2013

Ron;

That was beyond the scope of this test. This is the first try with the first roll, I haven't settled on a specific formulation. For those kind of tests with a gretag macbeth 24 colour patch (Will be using the X-Rite Passport), I will be using CD-4.

Anyway, here is an outdoor shot, colour balanced, but not profiled (profiling with a colour patch would remove crossover).

Photo Engineer · Feb 21, 2013

A bid low in saturation and contrast, isn't it?

PE

Athiril · Feb 21, 2013

Left the gamma as is on the scan. It's like that for the box speed shots.

Here is a gamma adjustment:

The base measures 0.27, 0.72, 0.86

The area of the clouds with the powerlines running over them measure 1.09, 1.61, 1.66

Photo Engineer · Feb 21, 2013

Very nice, but then I wonder what would happen if the gamma was increased by some means in development. Fuji has apparently done it somehow. I suggest pH.

PE

Athiril · Feb 21, 2013

PE; I have a suspicion this would print contrasty enough in the dark room.

But I would actually like to increase the neg contrast by a lot while retaining mostly a straight line, for something I want to test.

The development is very active, the higher E.I.'s have better gamma, but worse grain.

Some shots are very grainy in deeper shadow areas, more so than normal process, but normal areas appearing to offer similar or better grain but with better detail.

The colour is definately off, but serviceable when balanced.

This one appears to be a higher E.I. rather than box speed, I didn't take it (and it's not me!), mixed lighting (fluro) and overcast daylight filtered through opaque plastic things in the ceiling.

chuck94022 · Feb 21, 2013

How did you process, Dan? Temps, times, etc.

Athiril · Feb 21, 2013

Oh sorry, forgot.

The recipe I used is posted earlier, bath B pH was 11.1

Time was 3m 15s for Bath A (just because I decided that'd be funny )

And Bath B was 6 minutes.

The temperature of the solutions at the time was measured at 23 degrees celsius.

Initial agitation Bath A until first 30 seconds were up, then two inversions every 30 seconds.

Bath B, same, but 2 inversions every 60 seconds.

chuck94022 · Feb 21, 2013

Athiril said:
Okay I finally went to play around with another split bath out of curiousity.

Image (quick colour balance), the sharpness and grain are pretty good for this film (made in Japan Agfa Vista 400)

Bath A
Pinch of Sodium Sulphite
CD-2 9g/L
Sodium Sulphite 9.6g/L
Sodium Bisulphite 0.54g/L

Measured pH 7.1

Bath B
Potassium Carbonate 50g/L
Potassium Iodide 1.4mg/L
Sodium Thiocyanate 220mg/L (Im sure my thiocyanate needs drying out too btw).

I have to say I'm more than a little bit impressed with your results, Dan. One question: What does it mean to have a pinch of Sodium Sulphite, followed by 9.6 g/L of Sodium Sulphite? (And how much is a pinch anyway?)

Also, I'm assuming because the PH is neutral, nothing much is happening in Bath A other than uptake of the chemistry? It is Bath B that slams it into gear?

I guess this would have to be tried on various film formulations to determine whether it could be trustworthy, but my goodness it seems at least with this film to be delivering credible (not perfect but acceptable with adjustment) color. Would be interesting to see what would happen with something like Ektar.

chuck94022 · Feb 21, 2013

Oh one more question. Was the second bath a "to completion" time, or was 6 minutes critical?

Athiril · Feb 21, 2013

Pinch of sulphite - just a very tiny amount, take it from the 9.6g/L amount that's been measured out. I just formed this habbit when mixing developers, probably from doing it with Metol.

the CD-2 is mixed first, then the rest of the Sulphite. The Sulphite removes the HCl molecule off CD-2 iirc, and the H2SO4 off CD-4 and CD-3 (if you don't include a base initially it wont develop).

The bisulphite drops the pH down a bit, you can go lower than I did, but 7.1 is low enough for most purposes.

Some development has to occur in Bath A, or it is useless.

I've tried it with CD-3 before using ECN-2 film, I omitted the Sulphite as I wanted maximum saturation/dye formation etc in Bath A. Not even 4x the equivalent amount here of colour developer agent worked. I got very thin images from +5 stops overexposed, and that was it, and they were terrible colour iirc.

Development occurs in Bath A. Not much, but a reasonable amount. You can therefore alter affects and density with variations in time in Bath A.

Bath B continues development, but halts to a stop when it runs out of developer.

The last one I tried with CD-2 as at 7g/L which worked very well a well with limited testing on obscure films.

Print Film Test #3 by athiril, on Flickr

I was interested in it at the time to try and get good in camera pictorial results out of Vision Print Film (I've since had some luck with it using diluted E-6 first dev at 30c iirc and processing the rest as E-6), and put some 50D in as a control.

The recipe differs to the one I used here for the Agfa film in amounts and ingredients.

I'm currently interested in trying to figure out a good solvent style developer for C-41, ever since had some Agfa 400 go through E-6 by accident - messed up colours of course, but grain and detail were excellent.

chuck94022 said:
Oh one more question. Was the second bath a "to completion" time, or was 6 minutes critical?

My guess is that it's to completion by 6 minutes, as there isn't much developer sitting around anyway.

Also one key component to 'acceptable' results is to use a good colour balance - don't use the same balance/settings you do for printing or scanning normal C-41 - that will just not work out well, as it's obviously different.

If you're printing, shooting a greyscale on the roll and using that frame that to dial in your balance will help.

Photo Engineer · Feb 21, 2013

Ok, very good results!

That said, some critical comments.

1. CD2 is NOT good for C41 films. Image stability will be an issue.

2. The time and temp are not too critical as this 2 bath process is self limiting. As long as you get good imbibition of chemistry there should be no problem with development except for crossover, grain and sharpness. Color would probably be ok for the most part.

PE

chuck94022 · Feb 21, 2013

Photo Engineer said:
Ok, very good results!

That said, some critical comments.

1. CD2 is NOT good for C41 films. Image stability will be an issue.

What would be the nature of instability? Fading over time?

How would a change from CD2 to CD4 change this formula? Just one for one substitution? (And Dan, why did you use CD2 instead of CD4?)

2. The time and temp are not too critical as this 2 bath process is self limiting. As long as you get good imbibition of chemistry there should be no problem with development except for crossover, grain and sharpness. Color would probably be ok for the most part.

PE

The only problems will be crossover, grain and sharpness? Meaning, almost everything that's important?

Athiril · Feb 21, 2013

Atm, my CD-4 source is Flexicolor part C, I've worked out that 2x the normal amount per litre of regular C-41 developer is a good starting point for Bath A. I would prefer to get my hands on the dry salt before moving onto CD-4 testing though!

I'll get to that... eventually

Athiril · Feb 21, 2013

chuck94022 said:
What would be the nature of instability? Fading over time?

How would a change from CD2 to CD4 change this formula? Just one for one substitution? (And Dan, why did you use CD2 instead of CD4?)

Substitute Dignan's NCF-41 Bath A for my Bath A.

I used CD-2, because that's the dry CD salt I have. I was originally playing with CD-2 split bath to develop Vision Print ECP-2 film, I wanted pictorially good results from it because it has grain and sharpness of a ridiculous level and would make a good 35mm landscape film if I could get 'normal' results out of it. ECP-2 film is stable with CD-2, as the ECP-2 developer is CD-2 based.

So now I'm using it, because it's what I have. I want to play with the other controls (The other ingredients besides the CD agent) in Bath A and B in the mean time until I get dry CD-4.

Here is EI 6400 (the only sample) from this roll, I suspect it'd be worse in scenes you typically would reach for such high speed (dim with high contrast lighting/deep shadow and way-off daylight light sources)

Photo Engineer · Feb 21, 2013

1. CD4 was designed to work with the couplers and there is a big difference between CD2 and CD4 from a chemistry POV. One is far more polar than the other. So, you get different hue and stability. I did not mention hue before because stability is far the greater problem.

2. Yes, everything is a potential problem. But, curve shape may be perfect. Got that?

PE

Photo Engineer · Feb 21, 2013

IIRC, the current ECN and ECP is based on CD3.

PE

Athiril · Feb 21, 2013

The documentation I have says CD-2 for ECP-2
http://motion.kodak.com/motion/uploadedFiles/h2409a(1).pdf

Photo Engineer · Feb 22, 2013

The instructions for ECN-2, which are the most recent, use CD3.

See attached. Look on page 28.

PE

Athiril · Feb 22, 2013

For ECN-2 film, but the print film is ECP-2D process.

IE: This is the film I was trying to use it for - http://motion.kodak.com/motion/Products/Distribution_And_Exhibition/2383.htm

Though mine is a special order version with remjet.

Photo Engineer · Feb 22, 2013

Dan, are you sure? The current ECN and ECP go through the same process. The previous films went through 2 processes, but they were able to vastly improve the stability of the print film by using CD3. In fact, the new archival film is even better.

At least, that is the information given me by some west coast processors.

PE

Athiril · Feb 22, 2013

I'm just going off the data sheets from Kodak. The film I have is regular Vision Print Film (but SO with remjet added) which is specified as ECP-2D process in their current documentation.

I can't find any mention of running ECP-2 film through ECN-2. So that just sounds kind of suspicious, as I would think it'd be at least in the current documentation, if it were an official thing.

Why is there color crossover in divided C-41?

Attachments

Privacy & Transparency

Privacy & Transparency