I had an issue with a blue cast on the corners and edges of my converted scans.
This vignetting issue turned out to be caused by LR lens correction. LR will apply a default value to correct lens vignetting for any particular lens that LR has a profile for. It does so by increasing the exposure in the corners and along the edges. While this is fine for normal photos when it’s applied to an image of a negative it has the opposite effect and actually increases the vignetting. You can see this this by increasing the exposure of a converted RAW negative in LR , the image goes darker.
The severity will depend on the amount of lens vignetting correction LR applies, my Tamron 35mm macro lens has a lot of auto lens correction applied so I had a blue cast in the corners and along the edges.
Neg Lab Pro appears to turn on lens correction, even if I disable it in LR, when I convert the image with Neg Lab Pro the lens correction box gets ticked.
Once Neg Lab Pro has converted the image and I’ve applied it, I adjust the vignetting in LR by moving the slider to the left until the blue cast disappears and there is no vignetting.
The blue cast is really just underexposure and you would expect it just to go darker but it goes blue.
I hope this post is of value to anyone with a similar issue.
I just discovered this issue myself. I thought there was a major issue with my camera scan technique using a Nikon Z7, 60mm f/2.8G Micro, and Kaiser Slimlite Plano panel. I was applying brushes to fix the issue when I finally figured out that it was lens vignetting. I was getting a large orange/yellow patch in the center and blue around the edges.
I don’t think my particular issue is caused by LR lens profile corrections. Although it probably adds to my problem. In my case I think the major issue stems from the fact that these negatives were taken with a mediocre Tokina 24-200 lens from 2000. I believe this lens has a lot of vignetting. My solution was simply to apply vignetting to the converted scan to even the exposure across the frame. This seems to work.
With regard to lens profile corrections, I don’t know if NLP is turning on corrections. However, people should be aware that LR will use lens corrections for ALL images taken with almost all mirrorless cameras and there is no way to disable it. I may have to resort to using my D850 for negative scanning. I’m hoping I can retain the distortion corrections but turn off vignette corrections.
I just discovered the same problem. Was pulling my hair out not understanding why corners are showing vignetting. It would be great to have the option to disable NLP Pro from using lens profile correction.
Thanks, yeah that’s one way. I settled for simply disabling it after the NLP conversion. So: start without it, convert to NLP (NLP enables it automatically), manually disable it after NLP conversion. Any subsequent NLP tweaks of previously converted image do not re-enable lens profile, so the workaround only needs to be applied twice.
Still would be nice to just have the option for NLP to not autoenable lens profile.