C-41 Process Help

sillo · Jun 9, 2021

I'm kind of at a loss here on where to troubleshoot my process and could use some help. My developed rolls, specifically portra are coming out with blown highlights and very little shadow detail. The most obvious difference is the drastically different base color which is what is confusing me the most. I developed this last roll along with a control strip to make sure the process itself isn't an issue.

Here is the provided factory reference strip on top and the latest run on the bottom along with a closeup so you can see the plots are basically identical. You can see the base is a different shade however. The factory reference strip is slightly more pink. All the photos are untouched raw images that I screenshotted off of lightroom. I didn't want to export them as jpegs incase the compression caused color/contrast changes.

Here is my last roll of lab developed portra vs my latest home developed roll. The bottom home developed roll was processed in the same run as the control strip above. The batch number (I believe that's what the green text at the beginning of a roll is) is the same for both rolls of portra also.

Rebate of the same two strips

I'm using Kodak chemicals in a Jobo CPE2+. Process is two 30 second prewarms, LORR Developer for 3:25 (added 10 seconds according to z131 because first control strips came out slightly thin) at 100f used one shot, stop, wash, 7:00 Bleach, thorough wash, 7:00 Fix, thorough wash and into the stabilizer.

Developer was mixed middle of May and stored in 1 liter PET seltzer bottles. The liter of bleach had 3 rolls through it and is shaken up after each run to aerate. The fix was used one shot for this run to eliminate that as a variable. All mixed with distilled water.

I'm bringing my next roll to the lab just to make sure something isn't wrong with this box that I've been shooting, but I would really like to get this figured out. I'm almost inclined just to dump the rest of the developer I have and remix to see if that's causing the issue

Thanks in advance and if there is anything else I should add that could help diagnose just let me know.

YoIaMoNwater · Jun 9, 2021

Seems like the chemical has aged: https://www.35mmc.com/11/11/2017/ex...film-home-chemicals-dilemma-guest-post-aukje/

If you compare the examples in the link, the fresh chemical gave “pinker” negatives that you wanted.

As to if you should dump the developer, that’s up to you. I stopped shooting color negatives because you have to fiddle with them even if there’s a film profile (Silverfast). I have bottles of a year old Tetenal C41 kit that still gives me negatives (who knows when it will be completely exhausted) and I will still use them to develop more films as long as I can. Why? Because I’m not super nit picky and I’m not a professional photographer who needs everything/color to be normalized. I shoot C41 because it’s cheap and of its exposure latitude, if really wanted consistency I will shoot E6, get it lab processed and self scanned (with a calibrated scanner). Again, it’s up to you if you should dispose the chemicals (and hope you do it properly).

sillo · Jun 9, 2021

Thanks for the link. Guess it looks like I shouldn't have mixed in the starter with the replenisher while it's stored. Seems like it went off pretty fast and more drastically than any of the press kits I've used before which is surprising. It is also a little surprising the roll of portra came out so poorly while the control strip looked pretty decent.

I'm going to toss it (my town has a monthly hazardous waste disposal program) since the replenisher is so cheap and if I'm going through the trouble of using these chemicals I want good results. If I was fine with half baked c-41 I'd just stick to Paterson tanks and blix kits. With the scanner I have properly developed c41 comes out perfectly with no color correction needed. My last home developed roll needed significant corrections which is exactly what I want to avoid.

MattKing · Jun 9, 2021

Have you checked the accuracy of your thermometer? Your negatives look over-developed to me.

sillo · Jun 9, 2021

MattKing said:
Have you checked the accuracy of your thermometer? Your negatives look over-developed to me.

Yup, I have two supposedly 1% accurate thermometers that both were showing 100f. They do look that way in the highlights, but there is a pretty big lack of shadow detail in the negs/scans. On top of that the control strip looks pretty good.

YoIaMoNwater · Jun 9, 2021

sillo said:
Thanks for the link. Guess it looks like I shouldn't have mixed in the starter with the replenisher while it's stored. Seems like it went off pretty fast and more drastically than any of the press kits I've used before which is surprising. It is also a little surprising the roll of portra came out so poorly while the control strip looked pretty decent.

I'm going to toss it (my town has a monthly hazardous waste disposal program) since the replenisher is so cheap and if I'm going through the trouble of using these chemicals I want good results. If I was fine with half baked c-41 I'd just stick to Paterson tanks and blix kits. With the scanner I have properly developed c41 comes out perfectly with no color correction needed. My last home developed roll needed significant corrections which is exactly what I want to avoid.

What kit were you using? Nah it definitely is not a temperature/overdevelop issue. I’m also curious why the control strips were the same. How did you make them? I’m wondering if certain films tolerate aged developed better.

sillo · Jun 9, 2021

YoIaMoNwater said:
What kit were you using? Nah it definitely is not a temperature/overdevelop issue. I’m also curious why the control strips were the same. How did you make them? I’m wondering if certain films tolerate aged developed better.

I'm using the Kodak Flexicolor chemicals. LORR for the developer specifically. There are a lot of accounts online of people saying they last 6 months to a year in PET soda bottles with all the air squeezed out, especially being used one shot. I even developed a roll of Lomo 800 the day before and it came significantly better than the roll of portra. The film thing could make sense in that regard since lomo is a cheaper consumer stock. Maybe Kodak designed the consumer stocks to be developed in less controlled drug store labs.

The control strips are just off the shelf fuji control strips https://www.uniquephoto.com/product/cp4043facontrolstrip30stripsforra415485310/_/searchString/fuji control

Adrian Bacon · Jun 10, 2021

sillo said:
I'm kind of at a loss here on where to troubleshoot my process and could use some help. My developed rolls, specifically portra are coming out with blown highlights and very little shadow detail. The most obvious difference is the drastically different base color which is what is confusing me the most. I developed this last roll along with a control strip to make sure the process itself isn't an issue.

Here is the provided factory reference strip on top and the latest run on the bottom along with a closeup so you can see the plots are basically identical. You can see the base is a different shade however. The factory reference strip is slightly more pink. All the photos are untouched raw images that I screenshotted off of lightroom. I didn't want to export them as jpegs incase the compression caused color/contrast changes.

Here is my last roll of lab developed portra vs my latest home developed roll. The bottom home developed roll was processed in the same run as the control strip above. The batch number (I believe that's what the green text at the beginning of a roll is) is the same for both rolls of portra also.

Rebate of the same two strips

I'm using Kodak chemicals in a Jobo CPE2+. Process is two 30 second prewarms, LORR Developer for 3:25 (added 10 seconds according to z131 because first control strips came out slightly thin) at 100f used one shot, stop, wash, 7:00 Bleach, thorough wash, 7:00 Fix, thorough wash and into the stabilizer.

Developer was mixed middle of May and stored in 1 liter PET seltzer bottles. The liter of bleach had 3 rolls through it and is shaken up after each run to aerate. The fix was used one shot for this run to eliminate that as a variable. All mixed with distilled water.

I'm bringing my next roll to the lab just to make sure something isn't wrong with this box that I've been shooting, but I would really like to get this figured out. I'm almost inclined just to dump the rest of the developer I have and remix to see if that's causing the issue

Thanks in advance and if there is anything else I should add that could help diagnose just let me know.

I would verify that your temperature is correct.

The control strip should be analyzed more closely than just eyeballing it as the different color channels will in fact change differently depending on what is wrong. You can use numerical values in PS for each of the patches as long as the reference and the processed control strip are scanned exactly the same way. Look at the numerical values for each color channel and calculate the difference between HD and LD for each. Another useful metric is the difference between LD and DMIN, again for each color channel. It won't be as accurate as actually using a densitometer, but you can see big enough differences to use the Z131 manual to infer what is going on. For example, if your HD-LD is bigger than the reference, you're either running too hot, or running for too much time. If one (or two) color channels is significantly off from the reference, that's a clue, if your DMIN is high compared to the reference, another clue, etc.

koraks · Jun 10, 2021

I place my bets on a mixing error with the color developer. Discard and mix fresh, paying very close attention to the mixing instructions in the Kodak datasheet. They can be confusing sometimes if you have to convert the default quantities to the specific quantity you want to mix for your purposes. I suspect a fairly simple arithmetic error may have creeped in at some point.

AgX · Jun 10, 2021

YoIaMoNwater said:
Seems like the chemical has aged.

In this case his test strip should have come out different from the reference. At least at my laptop monitor I see zero difference between them. But I see the difference between the actual films.

Urs Gantner · Jun 10, 2021

What Adrian already said.... but nevertheless, the second control strip seems to have slightly more density. Personally I store all my pre-mixed chems in (filled to the top) glass bottles.

koraks · Jun 10, 2021

What seems rather disconcerting to me is the apparently low gamma on the magenta dye channel in the home-developed negatives, while yellow seems to have a rather high gamma in comparison with cyan being somewhere where you might expect it or perhaps a bit low. Hard to say without actual measurements of course. All this suggests *massive* crossover problems that aren't explained by a simple temperature deviation.

sillo · Jun 10, 2021

Thanks for the input so far everyone.

Adrian Bacon said:
I would verify that your temperature is correct.

The control strip should be analyzed more closely than just eyeballing it as the different color channels will in fact change differently depending on what is wrong. You can use numerical values in PS for each of the patches as long as the reference and the processed control strip are scanned exactly the same way. Look at the numerical values for each color channel and calculate the difference between HD and LD for each. Another useful metric is the difference between LD and DMIN, again for each color channel. It won't be as accurate as actually using a densitometer, but you can see big enough differences to use the Z131 manual to infer what is going on. For example, if your HD-LD is bigger than the reference, you're either running too hot, or running for too much time. If one (or two) color channels is significantly off from the reference, that's a clue, if your DMIN is high compared to the reference, another clue, etc.

This is actually something I was trying to do with LR, I just didn't really know how to interpret the data. Here are the PS numbers

Reference Strip - Yellow R181 G97 B24 DMAX 21 0 0 HD 35 8 1 LD 166 106 82 DMIN 195 132 95
Processed Strip - Yellow R176 G94 B23 DMAX 21 0 0 HD 32 1 0 LD 160 102 75 DMIN 188 130 89

koraks said:
I place my bets on a mixing error with the color developer. Discard and mix fresh, paying very close attention to the mixing instructions in the Kodak datasheet. They can be confusing sometimes if you have to convert the default quantities to the specific quantity you want to mix for your purposes. I suspect a fairly simple arithmetic error may have creeped in at some point.

I mixed them according to CIS-49. You can tell me if there's an error here but I used the entire 5000ml of replenisher, 1356ml of water and 197ml of starter for a total of 6.55 liters of working solution. Maybe mixing in the starter caused it to go off quicker? For the next batch I'm only going to add starter right before development.

koraks · Jun 10, 2021

sillo said:
Maybe mixing in the starter caused it to go off quicker?

No, I wouldn't expect it to. It's puzzling. Your LR measurements aren't too far off the mark, but c41 is finicky and you're only measuring at 8 bits per color channel this way.
Have you tried RA4 printing those negatives?

sillo · Jun 10, 2021

koraks said:
No, I wouldn't expect it to. It's puzzling. Your LR measurements aren't too far off the mark, but c41 is finicky and you're only measuring at 8 bits per color channel this way.
Have you tried RA4 printing those negatives?

It’s still only 8 bits as a raw file?

I printed a 6x6 Portra 160 negative that I processed 2 weeks ago, but with the same batch of developer. Scanned much better and printed at 6 seconds 65Y 55M. Tough to show how it looks in person but it looks neutral to my eye.

I’m on mobile right now so I can get the image to embed, here’s a link to the print https://imgur.com/a/qKEPP2j

foc · Jun 10, 2021

sillo said:
I’m on mobile right now so I can get the image to embed, here’s a link to the print https://imgur.com/a/qKEPP2j

To my eyes that print looks fine. As koraks said, I don't think adding the starter would have made it go off quicker.
You said you store the developer 6.5L in a series of 1L bottles, is that correct?
If so then one bottle is half full and would that half full bottle be from May?

As Adrian Bacon has said, it is nearly impossible to guess from control strips visually ( unless there is a serious problem).

When I looked at your posted image of the two control strips I couldn't see any differance.(of course on a screen/monitor it is hard)
When I looked at the strip of lab negs and home negs I could see a slight difference in the mask colour but nothing that would alarm me. If anything, the edge marking look slightly dense and could suggest over development, either by time or temperature (as has been already suggested above).

sillo · Jun 10, 2021

foc said:
To my eyes that print looks fine. As koraks said, I don't think adding the starter would have made it go off quicker.
You said you store the developer 6.5L in a series of 1L bottles, is that correct?
If so then one bottle is half full and would that half full bottle be from May?

As Adrian Bacon has said, it is nearly impossible to guess from control strips visually ( unless there is a serious problem).

When I looked at your posted image of the two control strips I couldn't see any differance.(of course on a screen/monitor it is hard)
When I looked at the strip of lab negs and home negs I could see a slight difference in the mask colour but nothing that would alarm me. If anything, the edge marking look slightly dense and could suggest over development, either by time or temperature (as has been already suggested above).

Anytime a 1l bottle wasn’t full all the air was squeezed out.

Also, the thing that confuses me is that if they were overdeveloped I would get an across the board boost in density. With the roll of Portra there’s a abysmal lack of shadow detail. You can kind of see how thin the darker areas are in the negatives while the lab developed roll is much flatter. I know it may be tough to tell over a computer screen, but the base color is drastically different in person. It’s only very slightly different on the control strip though.

Adrian Bacon · Jun 12, 2021

sillo said:
Thanks for the input so far everyone.

This is actually something I was trying to do with LR, I just didn't really know how to interpret the data. Here are the PS numbers

Reference Strip - Yellow R181 G97 B24 DMAX 21 0 0 HD 35 8 1 LD 166 106 82 DMIN 195 132 95
Processed Strip - Yellow R176 G94 B23 DMAX 21 0 0 HD 32 1 0 LD 160 102 75 DMIN 188 130 89

I mixed them according to CIS-49. You can tell me if there's an error here but I used the entire 5000ml of replenisher, 1356ml of water and 197ml of starter for a total of 6.55 liters of working solution. Maybe mixing in the starter caused it to go off quicker? For the next batch I'm only going to add starter right before development.

switch the sampler in the info panel in PS to output 15/16 bit values. The 8 bit values are a lot less accurate.

sillo · Jun 12, 2021

Adrian Bacon said:
switch the sampler in the info panel in PS to output 15/16 bit values. The 8 bit values are a lot less accurate.

ok, I’ll give that a try when I get home and put up the results.

Also had a roll developed by my lab to eliminate the highly unlikely chance I got a bad box of film and the roll came out perfect.

Adrian Bacon · Jun 12, 2021

Adrian Bacon said:
switch the sampler in the info panel in PS to output 15/16 bit values. The 8 bit values are a lot less accurate.

Also, make sure you're outputting a 16 bit tiff from from LR to PS in the ProPhoto color space. You want to avoid having the values get crunched together from a small color space, again, it's all about having as much precision as is reasonably possible.

mtjade2007 · Jun 12, 2021

Adrian Bacon said:
Also, make sure you're outputting a 16 bit tiff from from LR to PS in the ProPhoto color space. You want to avoid having the values get crunched together from a small color space, again, it's all about having as much precision as is reasonably possible.

I just scanned a 6x7 negative at 2820 dpi. With color depth at 8 bit it generated a 132 mega bytes tif file. To scan at 16 bit color depth it generated a file of 264 mega bytes. If your scanner is on a Win XP system this would probably take 10 minutes if not longer to scan at 16 bit color depth. 2820 input dpi is the upper limit of my Minolta film scanner. If you use one of those with 4000 input dpi the file size would be much greater and would take so much longer to scan. So I wonder if it is practical to scan at 16 bit color depth.

Adrian Bacon · Jun 13, 2021

mtjade2007 said:
I just scanned a 6x7 negative at 2820 dpi. With color depth at 8 bit it generated a 132 mega bytes tif file. To scan at 16 bit color depth it generated a file of 264 mega bytes. If your scanner is on a Win XP system this would probably take 10 minutes if not longer to scan at 16 bit color depth. 2820 input dpi is the upper limit of my Minolta film scanner. If you use one of those with 4000 input dpi the file size would be much greater and would take so much longer to scan. So I wonder if it is practical to scan at 16 bit color depth.

No. It is better to scan at a higher bit depth and less spatial resolution if you don't have the disk space. Also, the original scan isn't the one you keep, it's the one you start with. The one you keep is the one that is at the output resolution that you want. If you are scanning to keep a high quality archival copy, then you need to budget for the space that needs and scan at 16 bits and the highest native resolution your equipment supports.

sillo · Aug 8, 2021

So just to update. I ended up buying a thermocouple thermometer to make sure I'm getting accurate temperature readings and just to make my life easier. I also pulled back the development time to 3:15 and ignoring the control strips. At this point I was still getting some strong contrast and dense negatives. I decided to finally take Kodak's advice and not prewet the film since they explicitly state do not prewet film in z131. This seemed to be the final adjustment that has been giving me the negatives and density I have been looking for. My base is still not the same color as my lab processed film, but it scans perfectly with no adjustments needed in my pakon.

mohmad khatab · Aug 8, 2021

You didn't do anything wrong.
You have done all the steps efficiently.
The issue lies with the developer, I think it's a bit old and has lost the skewness.
As long as you want 100% standardized results, you should buy a completely new chemistry.
In my view, if you wanted to do a replinshmint, you couldn't, and there is a good reason for that, which is that this chemistry is not designed to be able to perform a replinshmint, of it.
There are other brands, perhaps Flexcolor chemistry, which works in the V30 professional development machines, and that's another story.

Nolan Zunk · Apr 5, 2022

Question-- probably already answered somewhere on this site. What's the best way to dispose of C-41 chemistry? I've been storing it in containers until now. Hoping to dispose of it in an environmentally conscious way. Local waste program hazardous material collection is what I'm thinking. Thoughts?

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