mframes

sandwich

by matt

BronicaSQA

Kodak Portra 400

4cm

by matt

Four centimetres. That’s the only difference between these two scans. The four centimetres is the distance between two different areas on my Epson v850’s platen where I placed the negative strip for scanning. The image on the left is from a scan with the negative strip held in the middle of the platen. The image on the right is from a scan where the negative strip was moved 4cm up towards the edge of the platen. This was a bit of a eureka moment for me. I haven’t yet figured out exactly why it happens, but every so often I end up with scans of C41 negatives that have a warm colour cast predominantly on one side. It’s always on the right side of the image and bleeds across towards the centre and beyond. Up until this moment, I was sure it was caused by my developing technique, e.g. maybe something going on with the bleach and/or fix stage of the C41 dev process. I process my black and white and C41 films at home and even though I’ve done hundreds, I’ve always associated this effect to something that’s my fault during the developing stage. I can go many rolls of film without seeing it, or I can see it on three or four frames from the same roll. It has always seemed totally random.

I scan my negatives upside down, so emulsion side facing up. This means there must be some kind of light leakage from the left side of the negative strip (left side as viewed when looking down on the strip upon on the platen). My current scanning set-up makes no use of the film holders that came with the Epson and instead, I use my Lomography Digitaliza mask with a cardboard shim of approximately 2mm underneath it. If I remove the shim, the effect is still there only it’s less obvious. I can only assume that the light source generated by the Epson (which I assume is evenly spread across the platen during scanning) is somehow being projected underneath my shim+mask on one side more than the other, hitting the film border (which is orange), throwing this warm light across the negative, causing the colour cast which is picked up by the scanner sensor. It’s probably happening on black and white film too but because the film borders of black and white film are very close to translucent (not quite, but near enough), it would cause a lightness from right to left on the image rather than a colour cast (it might just look like vignetting). And what do you know, I’ve seen this effect on black and white scans too, but it seems far less obvious.

I just need to figure out why it’s happening. Quite an interesting side-by-side comparison. Both images were scanned with the exact same settings in Silverfast and received no colour or level adjustment in Lightroom – only second stage dust correction (Silverfast iSRD did the heavy lifting). Investigation continues…