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Author Topic: Home C-41 - Purple tinged negatives with Rollei Digibase kit  (Read 8705 times)

horsemilk

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Home C-41 - Purple tinged negatives with Rollei Digibase kit
« on: March 10, 2015, 06:40:34 AM »

Hi there, I've just used this Rollei Digibase kit for the first time and I'm wondering if anyone can tell me why my negatives have turned out with this magenta/purple tone.

Here is an example:


This is not a scanning problem, as the lab negatives I've scanned don't have this issue.

I loaded 5 rolls into a steel tank and developed at 37C. I will try to offer a few things I might have done wrong, and maybe someone can tell me what could have caused this.

1. I actually spooled and loaded the rolls into the tank and they sat there for a month before I got around to developing them.
2. I initially rinsed the film twice in warm water, the water came off slightly green. I then pre-soaked the film for about 30 minutes, this wasn't my intention but I left it pre-soaking while I got my chemicals up to temperature, which took longer than I expected. When I emptied the tank from this pre-soak the water came of quite dark, like a purple-black I think.
3. I didn't rinse between steps, the instructions didn't mention this so I wasn't sure if one is supposed to.
4. Because the tank I used is quite big it takes a while to fill, probably 45 seconds or so to pour in each chemical. I started the timer when the tank was full, not when I started pouring, so each step was slightly lengthened.

Can anyone tell me what would have caused this? I have more film that  I am eager to develop but I don't want to ruin the rolls if this happens again.
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TonyW

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Re: Home C-41 - Purple tinged negatives with Rollei Digibase kit
« Reply #1 on: March 13, 2015, 09:40:22 AM »

Hi there, I've just used this Rollei Digibase kit for the first time and I'm wondering if anyone can tell me why my negatives have turned out with this magenta/purple tone.
It is not the negative as you are showing a reversal and I think the main issue is scanning and colour correction

Quote
This is not a scanning problem, as the lab negatives I've scanned don't have this issue.
The C41 process is quite demanding of control of time and temperature in particular the Colour developer critical for repeatable results and needs to be controlled to within a fairly tight range  temp +/- 0.15 degrees

For example Kodak C41
Developer 3:15 minute @37.8 degree C +/- 0.15
Bleach 6:30 minutes @ 24-41 degree
Wash 3:15 @24-41
Fixer 6:30 @24-41
Wash 3:15 @24-41
Stabilizer 1:30 24:41

I think you have made a number of errors that make the processing less than ideal
1.  Processing 37 instead 37.8C
2.  Allowing film to sit loaded onto spools for 1 month
3.  Rinsing and Presoak.  C41 instructions from Kodak make no mention but if your kit does then follow the instructions
4. Rinse between steps will probably be in the instructions and will normally be between the Bleach and Fix and Fix to Stabiliser
5.  I should not really take too long to fill a tank so this may require a bit of practice to ensure that all the films immersed fully in the shortest possible time.

On the example you posted I cannot really see any particular issues other than the conversion from Negative to Positive requiring colour balance shifts.  Even if your scanner has presets for a particular film it is unlikely that they will be correct due to your processing although they should be close for lab developed that follow sound QC

Quick play with your image into PS and select grey picker on paving suggest that nothing too far out.  Although there may be an airbell causing the green spot in the forest?

« Last Edit: March 13, 2015, 09:42:20 AM by TonyW »
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Some Guy

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Re: Home C-41 - Purple tinged negatives with Rollei Digibase kit
« Reply #2 on: March 13, 2015, 09:27:34 PM »

There used to be something about pH too with C-41.  Seems the smaller kits are a lot harder to get the pH within the working range window compared to the large mixes of 1 or 3.5 gallons.  Adding a presoak could dilute or alter the pH somewhat too and you'd get crossovers like magenta highlights and green shadows.  I know with our tanks we dropped the reels or hangers immediately into the developer them and used nitrogen burst for the agitation.  Kodak sold C-41 control strips for monitoring too. Patrick Dignan in Los Angeles, CA used to sell chemicals to some photo shops to mix up C-41 from scratch and was pretty adamant about pH control depending on the city water supply.

At home I did use a Jobo rotary with one gallon Kodak kits, but I think the tank was heated by spinning in the heated bath water along with the chemicals and then the developer went in the tanks pretty pretty quick.  Unicolor had some kits that combined the bleach and fixer, but results weren't too good over the separate baths.

SG
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horsemilk

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Re: Home C-41 - Purple tinged negatives with Rollei Digibase kit
« Reply #3 on: March 19, 2015, 12:32:04 PM »

OP here again with an update. Thank you to everyone who offered advice. In the end I decided to try again at a lower temp / longer dev to reduce the margin of error. I developed at 25C for 21 minutes, I did two canisters of film and both turned out satisfactory this time. See an example here:



I left the chemicals in the warm band, and a couple of hours later I then did another canister of 4x5 Portra 400, loaded on a Mod54. Although the water had cooled I warmed it back up to working temp with some boiling water and left it for 30 minutes to settle. Unfortunately this didn't go so well, there was a definite cyan shift with this batch.

I'm really not sure if I did something wrong - either the chemicals weren't up to temp or I agitated too much or too little. With the Mod54 holder I didn't want to dislodge the film sheets by inverting the tank a whole lot, so I just turned the agitation spool every 30 seconds. I'm not sure if this counts as agitating more or less. Anyway, you can see the results here:



Aside from the cyan shift, there is another obvious problem; on this sheet there is a large smear in the emulsion. I think this is because this sheet was improperly loaded and was touching another sheet, although it could also be because it fell on the floor while it was drying. It's disappointing because I really liked this particular frame, can anyone tell me if I can get rid of this by re-bleaching or fixing this sheet?
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