Here are some buns NLP conversions. for alot of them they come out super duper purple, especially if a photo is somewhat underexposed . ive even taken the photos on my canon r6m2 at bracketed expoures, under, middle and over exposure and each conversion is bad. i have an ideal setup with a cinestill light table, essential film holder, diy copy stand, tripod head leveler, and a canon EF 100m F2.8L. I shoot at 1/25 F8 Iso 100. Ive shoot other rolls at middle and 1 stop over exposure and the same weird color results. on my light table im on the correct WB, my camera is on auto wb.
I saw a post saying to significantly crop in to get a better calculation after setting the WB in LRC, and still nothing. ive moved my crop to different parts of the image and then converted the negative but it doesnt take out the big purple color cast. The negative itself looks good, i know it was not left in my car or exposed to heat. And no I am not converting the negative with the border.
I am genuinley so confused and frustrated because of how much time and effort ive invested for bad results. Yes i do know how to color grade these miscalculations out but I shouldnt have to be so good at colorgrading to undo this mess. wt am i doing wrong!!!
also yes my color profile is at negative lab v2.3 - frontier after conversion
It would help if you posted a shot of the negs. Also, are you sure your Cinestill light is set to the right setting?
You mentioned having the camera set to auto wb. Trying locking that to daylight. It doesn’t affect the RAW file, but it may send some confusing metadata.
Also try either a manual conversion in PS or download a free app like NegPy or the Filmomat trial and compare the result.
Please share the unedited camera scans. They can help us try things that might improve your situation. Use a cloud service if you have any or use wetransfer or any other file sharing service.
How old are the original films?
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Try using a Custom White Balance on the light source itself, before copying your negatives to raw files. This will expose the orange mask at the correct values.
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Use the eyedropper tool in LrC to set the white balance of the film, using a clear area between frames. This will get rid of the orange mask, leaving the correct rendering of the image in negative form.
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Only after steps 1 and 2 should you crop the image slightly within the 35mm frame. Set a border buffer of around 5%.
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Convert your images and evaluate…
Is the Cinestill light table properly masked off so that no stray light illuminates the surrounding area? Are you working in a very dimly lit room? The point is to eliminate all stray light sources from entering the lens.
It sounds like the light source is very dim. I’m using exposures around 1/125 at f5.6 at ISO 200 (on Micro 4/3). My source is a Viltrox L-116t video light panel under the diffusion panel of the Essential Film Holder.
Yes im using the proper custom white balance, Yes i already used the eyedropper for white balance, Yes I already said I cropped out out the film mask in my original post, Yes the light is masked off. Im shooting at F8 for a sharper image, iso 100 for less digital noise, leaving me with whatever shutter speed that im firing with a remote trigger. I kinda already stated this in my original post.
Hey, chiming in as the owner of a mini lab with over 10,000 rolls processed and scanned. I now use a Noritsu but was using a DSLR set up a bit ago. I think the issue isn’t the scanning; it’s the dev.
While the negative LOOK healthy, issues with color like this are basically undetectable when looking at the negatives. The color space is so compressed it’s almost impossible to tell. To me, this looks like the scan is good, but the colors in the Neg are bad. The giveaway to me is the fact that your highlights are more accurate than your shadows. Rather than everything being wonky.
The way NLP creates it’s WB is using the waveform. It’s a mathematical algorithm attempting to match the Red, Green, and Blue channel curves. This is as close as you can get to true neutral..mathematically speaking…says NLP.
There’s just a heavy magenta cast in your shadows. To me, this looks like it could be a number of things all stacked together.
A small amount of underexposure in camera, noting the fact that there is loads of detail in the clouds, and they’re not even close to clipping, which means the shadows make sense at their current value. The Cappybara looks the best exposed and suffers the least from the color shifts in the shadows.
I would say these might have been processed a bit too long…like 45 seconds or more? Do you do the dev? When you dump out the Dev, do you go straight to bleach or Blix? Or do you use an intermediate rinse step? What was your dev time? This also looks like it could be an issue with Temp.
A good way to check is to do a manual conversion using your Curves and that’s how you’ll know if it’s the software or your Dev. It’s pretty much impossible to get this bad of a conversion because of your scanning setup. If it was coming from that, there would be horribly obvious problems.
Go into your curves panel and for each channel [R, G, & B separately] just invert your Black and white so that they line up with the waveform per color channel. Meaning the black point is set to full white right at the edge of the waveform and have the white point set at the max black, but on the other edge of the waveform…if that makes sense.
Do this separately for each channel, not for the collected white. This will give you a rough inversion. If the colors look decent in this, then NLP is going bonkers, but more than likely, you’ll see some pretty wonky colors here that don’t look too far off from the NLP conversion. Which means it’s baked into the negative.
And judging by the quality of your highlights, this is just a HEFTY shadow cast.
The very last thing I’ll throw out is that if you improperly Bleach & Fix, you can add a heavy green/yellow cast to your highlights, and if you were to correct for that…you’d be adding purple/blue to the shadows. I don’t think this is what’s going on here though. Because you would see decreased saturation, increased contrast, and a loss of detail in your highlights. I don’t see any of those other side effects.
Happy to help further if you’ve got more questions.
Amazing insight I never thought of.
I shot 24 rolls of film throughout a month in japan. I developed the first 12 rolls (chronologically) in Osaka at a film lab in Dontonbori so i can bring back the negatives in sleeves to save space during the trip back home. Ive been self scanning in chronological order with the exception of my last roll where I whent drinkning with friends on my last night so i can post them sooner. This last roll came out amazing conversion wise. The 2 variables that changed are the lab that I developed at the camera that I shot on.
The orginal camera i shot on was a minolta cle that someone tried to steal from me but got broken when i fought him back for it. So I shot the 2nd half of the trip on a fuji tiara 28mm point and shoot. so yah development was probably the thing. Im open to hear more suggestions from the community but Ill update this thread when I scan my negatives shot on the fuji tiara, which was developed at Im still developing in san diego, As opposed to osaka where I currently got the sh*t results. Thank you media film dude
Hi ,sanchez_productions.
I read your findings, and am curious. Your equipment sounds top notch ,but I had similar problems with purple coloration when I started out . I self develop - and my chemicals were either worn out or my time/temps were off back when I started.
Do you develop your own film ?
koenji75 is right about checking your negs.
mediamfilmdude I think you have the right track. Can’t beat experience
Very interesting and very good to have the benefit of your experience on here, especially regarding the correct processing of colour negative film and what incorrect processing might look like on the negative.
Although it’s not true in this case I think a lot of people coming fresh to NLP may develop their own colour negative films using some of the kits that are available and I can’t really see that they can possibly achieve the consistency necessary when temperature and time tolerances are so fine for the C41 process, unless perhaps they have some expensive equipment to help them from the likes of Jobo or Filmomat etc. Presumably a properly run mini lab should provide such consistency, but I guess some operators might cut corners.
Wow, thanks for taking the time to read all of that. I’d happily answer all of these questions and many more. I really wish I’d had someone to tell me this stuff when I started instead of having to figure so much of it out through trial and error.
I actually think a lot of apparent NLP problems can stem from bad development. Film is basically one giant game of whack-a-mole: is it the exposure? The development? The scan? The conversion? Trying to lock down one variable so you can accurately test another is incredibly difficult with film. But there are a few things I’d recommend if you’re trying to get genuinely lab-grade consistency out of C-41 at home.
Start with good chemistry.
Cinestill’s kits are better now than they used to be, especially since their partnership with Kodak, but if you can get Bellini chemistry, that’s probably my first choice for home development. Unfortunately, it’s much easier to get in Europe than in the US.
Powdered chemistry creates another problem if you only want to mix half or a quarter of a kit. Never divide the dry powder itself. There can be multiple different chemicals in that bag with different particle sizes and densities, so half the powder does not necessarily mean half of every ingredient. Instead, dissolve the entire packet into a small, known amount of water first. For example, mix the whole packet into 100mL of water and make your own liquid concentrate. Mix it thoroughly until everything is completely dissolved. Now the chemistry is homogeneous: if you want a half batch, use half of that concentrate; if you want a quarter batch, use a quarter of it.
Better yet, weigh that concentrate instead of measuring it by volume. That’s one of the bigger differences between how I mix chemistry in the lab and how most consumer instructions are written: I mix by mass, not volume. For example, my developer uses roughly 106g of Part A, 19g of Part B, and 39g of Part C. The manufacturer may give those amounts in milliliters, but once I’ve established their mass, weighing them is much more repeatable.
Volume changes with temperature because the density of a liquid changes as it expands and contracts. You also have meniscus-reading error, graduations on cylinders that may not be perfectly accurate, and thick concentrates that cling to the walls of whatever you’re measuring them in. Mass eliminates most of that. A properly calibrated scale is measuring the actual quantity of material present regardless of whether that concentrate is sitting at 65°F or 100°F. I use Ruishan lab scales and have had good luck with them.
If you want to convert the manufacturer’s recommended volume into mass, weigh only the chemistry itself. Put an empty container on the scale, tare it to zero, pour the entire contents of Part A into it, and record the mass of the liquid. Repeat that with Parts B and C. Do exactly the same thing with the liquid concentrates you make yourself from powdered chemistry: tare the receiving container and weigh the concentrate itself, not the bottle plus the concentrate.
I also wouldn’t establish your ratio from one kit. Do this across maybe 5–10 kits and calculate an average. You may be surprised to find the actual amount supplied by the manufacturer varying by 5–10g between packages. For each of those first few kits, measure the full mass before dividing it. Once you’ve built a good average, you can use those numbers going forward and scale your batches very consistently.
Next is temperature.
This causes way more problems than people realize. If your water bath is exactly 100°F, then 100°F is the absolute hottest your chemistry could ever theoretically become. It can become as hot as the water around it, but it cannot become hotter than the thing supplying the heat. And that’s before accounting for all of the heat you’re simultaneously losing to the bottle, room air, tank, thermometer, handling, etc. In the real world, a 100°F bath means your chemistry will approach 100°F but probably never actually stabilize there.
The other part people miss is that heat transfer is driven by the temperature gradient. If your developer is 70°F and your bath is 102°F, there’s a 32-degree delta between them, so heat transfers very quickly. Once the developer reaches 99°F, there’s only a 3-degree delta. At 101°F, there’s only a 1-degree delta. As the two temperatures approach equilibrium, the rate of heat transfer slows dramatically, which means the last degree or two can take 25–30 minutes depending on your bottle, chemistry volume, circulation, and setup.
So either give your chemistry a long time to fully stabilize or, much better, use a calibrated digital thermometer and measure the actual developer. Don’t trust the number on the sous vide and assume the chemistry matches it. I want my actual developer held within about a 0.4°F delta of target temperature.
I’ve found that a circulating bath around 102°F will generally hold the actual chemistry very close to 100°F once everything has stabilized. Your exact setup may vary, which is why the thermometer is important. Think of it the same way as a sous vide: you need the surrounding heat source slightly above your desired internal temperature because you’re constantly fighting heat loss.
Once you finally get everything to temperature, the goal is to stay at temperature. And that brings us to probably the most controversial step in home C-41:
The pre-soak.
In a proper lab process, you generally do not want a pre-soak at all because the water itself introduces another set of variables before development begins. It changes the condition of the emulsion, affects swelling and chemical uptake, and can alter density and diffusion behavior. Different emulsions also react differently. In my experience, Ultramax and Portra 400 are noticeably more sensitive to an extended pre-soak than films like Kodacolor or Gold.
So why use one at home? Because the thermal situation is completely different. In dip-and-dunk processing, I can put a handful of room-temperature rolls into a giant tank containing gallons of hot chemistry and they barely make a dent in the temperature. At home, you may have a room-temperature tank, reels, center column, lid, and multiple rolls of film, and then pour only 500–1000mL of developer into all that cold material. That can absolutely crash the temperature of your developer.
In that situation, I think the temperature stability gained from a very short pre-soak outweighs the negatives introduced by the pre-soak itself. The sweet spot is roughly 30–45 seconds. Go shorter and whether you actually get the tank, reels, and film up to temperature becomes hit-or-miss. Go longer and you start introducing more of the issues that make extended pre-soaking undesirable in the first place.
The pre-soak water itself should also be 102°F, the same as your bath. You’re specifically trying to bring all of that thermal mass up to process temperature before the developer arrives.
Hard rule: from the instant that 102°F pre-soak water first touches the film to the instant developer first touches the film, do not exceed one minute.
That one minute includes the soak itself, dumping the water, and pouring in the developer. So have your developer measured, stabilized, and sitting there ready to go before you start. About 30–45 seconds at 102°F, dump it, and immediately put the developer in.
Then comes agitation.
Once temperature and that transition into developer are under control, agitation is another variable worth making repeatable. Its purpose is to continuously replace the locally exhausted chemistry sitting against the emulsion with fresh developer. It also prevents bromide, a byproduct of development, from accumulating unevenly around the film surface. If bromide is allowed to pool or move unevenly across the negative, it restrains development locally and can create bromide drag.
For maximum consistency, I prefer gentle, continuous rotary agitation over intermittent inversions. You’ll need a daylight tank with a proper sealed lid that can operate horizontally, like a Patterson or Jobo. Put the tank on its side in your temperature-controlled water bath and rotate it. Congratulations: you have invented the rotary processor.
Treat 20 RPM as your lower limit, which is about one complete revolution every three seconds, and 60 RPM as your upper limit, or about one revolution per second. Anywhere within that 20–60 RPM range is perfectly fine. You’re not going to materially alter the film because you picked 27 RPM instead of 43 RPM; what matters is that you have continuous, consistent chemical movement and that you stay within those boundaries.
Yes, doing that manually is more work than a few inversions every 30 seconds. But you signed up to shoot film. If you’re trying to squeeze every last drop of dEm tOnEz out of your negatives, don’t take the lazy way out. If avoiding all that work was the goal, well… shoot digital.
Now the part I think gets overlooked the most: bleach and fixer.
Bleach in C-41 serves two purposes, and the first one is especially important: The bleach is your STOP BATH. When developer time is up, you want development arrested immediately. That’s why the transition should be: DEVELOPER → BLEACH
No intermediate water rinse. Developer out, bleach in.
Yes, you’ll carry a small amount of developer into the bleach. That’s okay. Your developer is generally going to reach exhaustion long before that small amount of carryover ruins a properly maintained bleach bath. The more important thing is stopping development quickly and consistently.
Water doesn’t accomplish that properly because it mostly just dilutes the developer. An ordinary acetic-acid darkroom stop bath doesn’t accomplish the same thing either. C-41 bleaching chemistry uses ferric chelates such as EDTA- or PDTA-based systems, and the bleach’s chemical environment rapidly arrests development while beginning the next reaction. That immediate stop is important to color balance because you don’t want development continuing unpredictably while you’re rinsing or screwing around between steps.
The bleach’s second job is dealing with the metallic silver created during development. The easiest conceptual way to understand it is that the bleach UN-develops the silver. Developer converted exposed silver halide into metallic silver. Bleach oxidizes that metallic silver back into silver compounds that the fixer can remove. Development builds the silver image; bleach chemically un-develops that silver image; fixer gets rid of it.
As bleach becomes exhausted, that process takes longer and longer. With a healthy separate bleach, I generally wouldn’t expect it to require substantially more than about 7 minutes. If it still isn’t getting the job done at seven minutes, your bleach is probably toast.
Then comes fixer—or the fixer half of BLIX.
Fixer dissolves the silver compounds remaining in the emulsion. With black-and-white film, the developed metallic silver is your finished image, so you preserve it. With color negative film, the dyes are the finished image. The entire point of bleaching is to convert the developed metallic silver into something the fixer can remove, so by the end of C-41 processing you want essentially all of the silver gone, leaving the dye image behind.
This is also why I strongly prefer separate bleach and fixer if you’re chasing maximum consistency. BLIX works, but you’ve got two processes happening in one solution: one component is trying to convert metallic silver into removable silver compounds while the other is simultaneously trying to dissolve those compounds. As BLIX gets closer to exhaustion, those competing reactions make its behavior increasingly complicated. It starts getting closer to a kind of chemical equilibrium instead of simply behaving like an individual bath reaching straightforward saturation. Separate bleach and fixer are much easier to understand, monitor, and diagnose.
Luckily, everything after developer is much more forgiving because bleach and fix are essentially process-to-completion steps. If you find out your bleach was exhausted, you can put the film back into fresh bleach and re-bleach it. If the film wasn’t completely fixed, you can re-fix it.
So if I were trying to make home C-41 genuinely repeatable, the part I’d obsess over is:
temperature stabilization → 30–45 sec pre-soak at 102°F → developer → IMMEDIATE bleach
Get that pipeline absolutely nailed. Keep the actual developer within roughly 0.4°F of target, keep the total pre-soak-to-developer interval under one minute, go straight from developer into bleach, and make your agitation mechanically repeatable.
Once you’ve locked all of that down, you’ve eliminated a massive number of variables before NLP ever even sees the negative. And that’s really why I think people sometimes chase their tails with scanning and NLP settings. If the relationship between the cyan, magenta, and yellow dye layers is already screwed up in the negative, NLP can’t know that. It just sees the data you gave it.
You can have a fantastic camera-scanning setup, perfectly even backlight, correct white balance, excellent lens, perfect focus, and a technically perfect RAW capture of a poorly processed negative.
At that point, the scan isn’t wrong. It’s just doing a really accurate job of showing you what’s baked into the film.
Feel free to shoot me a message on Instagram @mediamfilmlab if you’re a fellow nerd who actually read all of this. I’m happy to help any way I can.
This should be its own post somewhere, for sure!
Brilliant, thank you for taking the time to post this really valuable information for anyone who processes their own colour negative films.
Indeed, and someone might simply start it witch coy-pasting…preferably the authors … and in a sequence that makes sense.