One issue with the raw file is that the color balance does not seem consistent from left to right, being a bit warmer on the left than the right of the frame. Whenever I’m digitizing film, whether positive or negative, I always shoot a “blank” of just the light source, which in my case is a high-quality 5600K LED light panel. I position the film, then remove it to ensure that the area I’m shooting matches with the film. This “blank” does two things - first it’s a white balance check in RawTherapee, which I use for the film (at least if it’s color transparency film). Second, it provides a reference to ensure that the brightness and color are consistent across the frame. This can be done easily by referencing the histogram on the camera LCD. If it’s a very narrow histogram, it means that the brightness is consistent in all parts of the frame. If it’s wider, it means there’s more variation and you need to make corrections. This variation can be caused by the light source being brighter on one side of the frame, by specs of dirt on the light table, or even by using a wide aperture that has darkening on the edges of the frame. With my Nikkor 60 f2.8 micro lens I need to stop down at least to f5.6 to eliminate this vignetting, and I generally use f8 - f11. This screenshot of a “blank” shows that the exposure and color are consistent through the frame.
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