Sync scene problems

I’m having trouble with the ‘sync scene’ feature. When trying to use it the colour and contrast of the images being synced goes haywire and I can’t figure it out.

What I’m trying to do is use an initial conversion of an image (an alternative process negative digitised in one photograph) as the basis for the conversion of several detail photographs of that image. I want to stitch together the detail photographs later to make a larger printing file.
(The neg lab pro conversion seems to work much better from the single digital photograph than when I stitch together the images before conversion, so I want to use the single digital image as the base conversion. I thought that was what sync scene would achieve but I can’t get any useable result.)

All images were taken in the same controlled conditions on a lightbox. Same camera, lens, exposure, and white balance has been synced. All are CR2 files.

I start with this:

And get this:

I’ve been over the instructions - only the first image is converted, i edit it how I want, and then I try to sync scene with the other unconverted images. I’ve tried uncoverting them all numerous times, using the first image uncropped, copying the files to a new folder and using them… all ends up in bizarre synced images.

I’m using PC, Lightroom Classic, latest version of neg lab pro. Help much appreciated!

Wanted to add that using the lightroom panorama stitch and then converting I can get a kind-of similar result, but not quite as nice (I think because at a very high resolution the neg lab software is seeing the very hefty film grain and taking that into account).

Hi @Polaroid

Two quick things to check.

  1. In Lightroom, can you look just beneath the histogram at the ISO, Aperture and Shutter Speed of each shot and confirm that they exactly match the first image? In other cases, I’ve seen photographers use Aperture Priority during shooting (instead of fully manual) in which case, the camera might be setting different shutter speeds for each shot (without you being aware, since you haven’t changed any settings). It’s worth confirming! The close up negative images do appear to be a bit darker than the first shot, which would result in them being brighter if inverted with the same settings.

  2. Also possible, you might be seeing some setup issues as you move your camera closer to all that unmasked light shooting up directly from the Lightbox into your camera lens, which can cause lens flare, sensor flare and other issues. If you can minimize that direct light by masking it, it should help your consistency a great deal.

Hope that helps!