Colour changes from centre to edge

I’m trying out NLP and on a lot of my images the ‘white balance’ appears to change from the centre to the edge of the frame. It is always warmer in the centre and colder at the edges. The image below demonstrates this. It is particularly bad in this image as colour should be uniform throughout. It is definitely related to my capture set up as it happens across all negatives and I can see blue tinting on the black film mask on the RAW file before crop and conversion.

My set up is a Canon 650D with a Sigma 50mm F2.8 Macro, at F8, ISO100, 1/5 shutter. I use a small light table as a source, and have tried varying the distance between the film and light table but no luck. I’ve tried with and without the lens correction profile in Lightroom.

Any advice on how to fix this would be greatly appreciated.


Just to provide an update to this - it looks like it was caused by light bleeding onto the lens.

Since I was using a 1:1 macro lens with a hood I didn’t think it would be a problem, but obviously due to the smaller sensor and hence the greater distance between the lens and light source it allowed extra light to bleed through.

I have used a thick cardboard cutout slightly larger than a 35mm frame and placed it between the film mask and light source, and that appears to have alleviated the problem.

Hi @nuttybloke, you seem to have a tough issue… Have you tried taking the shots in complete darkness? Stray light can cause such issues, so it is a good idea to prevent light from entering between lens and negative or avoid altogether any light other than the backlight.

I’ve inverted your shot and the yellow area looks like a reflection from a window or door…