Beginner Question - Inconsistent Film Borders

Hey everyone. Brand new to DSLR scanning, and film in general. Am using NLP to convert my scans, and am noticing that the film borders are very inconsistent between images. My guess is when you crop in to remove the borders from the conversion process, its converting based on the image alone, and once the conversion settings have been applied, its then by-proxy causing inconsistencies in the borders. Am wondering if this is totally normal, or if i am doing something else wrong, and as a result may be ending up with inconsistencies in the scans themselves as well.
At the end of the day, im not overly fussed as long as the photos themselves look good, but i also love throwing together contact sheets for posters, and having the inconsistent borders on the contact sheets dosent look very good.
Any help would be much appreciated. Thanks!

Hi there, welcome to the forum. Here’s my take on it, and it doesn’t really involve NLP directly.

Suppose someone was to do an actual contact sheet for you in the darkroom, so they lay out the colour negatives over a sheet of colour paper, expose it and process it. Similarly, although it’s not entirely straightforward, you could lay out the negatives on a light box, photograph them and ‘process’ them using software, NLP wil do it. In both cases of course the film rebate will be consistent because it’s not been exposed to light in the camera. However the individual frames will likely not be consistent, they may be under or over exposed or shot under different lighting conditions, inside, outside, sunny days, cloudy days etc. This means that to correctly interpret them the individual frames will need different colour settings and different exposure so you will now see the rebate, or the look of it, will change as you’ve shown here.

Incidentally I don’t see any flare on these in the limited view we have of them but photographing/copying with the full rebate including sprocket holes can run the risk of degrading the actual image because of this ‘non image forming’ light.

Hi Harry, thank you for your detailed response. and everything said here makes perfect sense. Its nice to know my workflow has been correct so far.

I had considered making virtual copies of all of the frames, and scene syncing all of those copies with the same settings allowing me to get the consistent borders, then just making the correctly converted frames back in in PS, but as i’m not actually contacts sheets for every shoot and its only been for a couple of posters, its probably a waste of time for now unless its for a specific project.

And yes, i have heard about the risk of flaring when scanning in the full rebate, From the testing that i have done so far, i luckily havent had any major issues flaring or light inconsistencies with scanning the sprockets. I personally quite like the look of retaining the film borders, so im happy to take a small bit of degradation to retain those borders if i must, but so far, at least with the setup im using, i luckily havent noticed anything major.

Great, glad that makes sense to you. I used to print contact sheets like that in the darkroom, they’re so useful because I could look at the frames overall and then have a pretty good idea as to how to adjust the filtration for the individual frames in the enlarger.

Your setup must be good, not really a sign of flare though those sprocket holes.