Hi. I’m in the same process of archiving a lot of negatives from my old man. I already did a few thousands pictures and negadoctor is imho the best tool for this (and I have lightroom and Negative Lab Pro, Smartconvert, and a few others). First of all, deactivate the color calibration and the tone mappers.
Before negadoctor, be sure to use a constant white balance for the entire roll. I use the neutral of my camera. It could also be taken on the film base directly, or on the light that you are using to backlight your negatives (official recommandation from the darktable doc). I saw a few debates online about this. Some purists even totally deactivate it. The most important thing : copy paste the white balance to the entire roll.
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Fix the Dmin (film support color or whatever it is called in english, the first item) on a portion of the film base (unexposed). I shoot a picture only for that, with a good portion of the film base between 2 pictures. My advice : don’t rely on 3 pixels on the border of the frame, use a large area. This part will adjust the channels R, G and B so the film base is black. Copy paste to the entire roll.
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For the Dmax, I use the picker on the brighter picture of my roll, sometimes I correct the value a little bit, and copy paste it to the entire roll. Most of the time, it’s good enough for every picture.
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I don’t touch the exposure bias.
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Here comes the tricky part : the color correction. Most of the time, I don’t really really need to correct the colors of the shadows, it’s not mandatory. The corrections of the shadows are already imo partially covered with the Dmin, but you can do it. If your film is old and damaged, you maye have to do it.
The white balance of the highlights will be the most important part. Now you have to chose a frame with something in it that you think is white. Ideally, for a daylight film, a daylight picture of course. You may have to do some trial and error to achieve this. You can use the picker, then modify the R, G and B values, of course. Copy paste the value to the entire roll. You will very quickly see if the value makes sense or if there is a noticeable color tint remaining. Adjust, copy paste to the roll, adjust, copy paste to the roll, etc until you think that it’s a good base to begin with. By copy pasting this unique value to the entire roll, you will discover for each picture if the light was warm, cold, etc. You will be aware of the mood, then how much you correct it is up to you :
- Here come the indivual adjustments. Personally, I still use the highlight white balance inside negadoctor to color balance the individual pictures if they need it. It gives way better results for me than a color calibration instance put after negadoctor in the pipeline. It’s roughly equivalent to the color balance tool, but for various reasons I prefer to correct in negadoctor as well.
I use the 3 sliders like I would use a white balance tool to correct every normal, positive raw file. But most photographers are not used to use 3 channels like that, we are used to the 2 sliders : Kelvin and tint. A rule of thumb to use the 3 sliders without getting lost :
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If you want to make your image warmer, add +1 on the red channel and -2 on the blue channel. Or +2 and -4, + 5 and -10. This “-2 ratio” will give you roughly the equivalence of a movement of the kelvin slider toward a warmer picture. Do the opposite if you want a colder white balance.
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use the green slider like you would use a tint slider in a classic white balance.
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Then use the print properties (third item) to individually adjust the tonality of your picture.
After that, use whatever you want in Darktable to fine tune your picture. But I almost never use anything else to correct the colors.
- A bonus tip about the color profile that you could use inside darktable, that is not related to the consistency that you’re looking for. The official recommandation is to use the standard color matrix. I think that it often lead to some nuclear greens. For several reasons explained here : Input color profile to use for negatives I use linear REC2020 as both the working profile and the input profile. It’s way smoother. I use it with some corrections using the RGB Primaries module placed just before negadoctor in the pipeline. I give you the values :
I hope that it will help you !
