Heya I need some help to id what the cause of this is. I suspect it’s from the negative not being completely flat. Some negatives can have this yellow faint colour appear in the blues of an image, most notably in skies. I seem to get weirder colours with blues compared to the rest. Why I think it’s cause the film isn’t completely flat is because other negatives in the roll are completely fine. This will often be the start or end of a 3 frame strip but when the film has been cut to only 2 frames it seems there’s not enough to push it all the way through and keep it flat without it coming out the other side. Have others had this issue with this holder?
You can test your theory/suspicion by putting the negative on the backlight, without film holder. Use a piece of glass to flatten the negative. Then scan and check the outcome. If the streaks are still there, the cause lies somewhere else.
Can you see the streaks on unaltered RAWs or exported files that you convert by flipping the tone curves manually?
You could also turn the negatives through 180º and see if the position of the strange blemish alters. Are you positive that no extraneous light from within the room can reflect off the top surface of the negative, are they shiny side up?
Hmm, the streaks look like forward and backward slashes. Does this change when you rotate or flip the negative? Can you also put a black cloth over the setup in order to eliminate stray light. Also take care that you don’t have any lights from a smartwatch (etc.) reaching the negative or lens.
It seems there was a mark on the lens which i;ve cleaned which is that faint light line on the right and left. The other thing is the flipped over negative has a stronger yellow cast.
Had a look at the two files and the yellow blotch come up differently.
The flipped image has lost most of the streak … which leads mo to conclude that the yellow mark was caused by stray light, something that can happen easily, e.g. reflected from an arm reaching out to the lens or camera.
Note that I converted the images in a different app and manually in order to confirm that Lr/NLP have nothing to do with the issue, except to make it visible, that is.
My recommendation: Rescan the offenders making sure that you work in a dark room and with nothing that can shed stray light onto the negative. Darken the room and mask off all unwanted light.
Have you perhaps got a blank unexposed frame you could scan? That might help to identify the source. Could the light be reflecting back off part of your setup perhaps?
Sorry for the late reply! I’ve still been struggling to identify this fully and mask off the light. Here’s a blank frame in this folder. Negatives - Google Drive
There is definitely something reflecting back off the setup.
I wonder if I need to lower the intensity of the light source instead of at 100%?
I think I’m going to need to create a tube of black card from the lens to the light source because the bright led light is reflecting back into the lens even with it all masked off but the frame
Some people have also mentioned that using a polarizing filter helps
If it is being solely caused by the the panel itself then I wouldn’t have thought that reducing its intensity will help because you’ll have to lengthen your exposure to compensate, worth a try though. Certainly some kind of tunnel around your holder should avoid lights in the room or from parts of your setup from reflecting, a lens hood, an extra long one, might help as well, especially if it reaches into this tunnel. You could also arrange to have a piece of blank card with a circle for the lens filter thread cut out and hold this in place with the lens hood so that it shields anything that might reflect off your setup.
My apologies, for my last comment (now deleted) I thought I was replying to a different post.
No certainly not aware of issues with the 120mm Pentax lens for scanning, it seems to be a popular lens on the GFX. I don’t know how much you have had to move your lens away, you can afford to do that a little with your 50MP GFX, but a long 67mm lens hood may solve the problem together with your tunnel.
