I have just received a developed film (portra) that i have used in a mamiya 645 pro, across several frames there is a stripe from top to bottom take a look at the picture (crop). Is this a lab error?
I have another film taken a few days later without the stripes, but i might have used a different magazine.
Looks like a scanner artifact to me. A reference strip that isn't clean can cause that in home scanners. I'm not certain how this would work in commercial scanners.
Can you see the stripe in the negatives or only the scan. Not clear from your post.
I have scanned the image at an Epson 850, i can’t see it on the negative, but it’s so small so i thought i need a powerful magnifying glass. I moved the film inside the film holder and the stripe appeared at the same place.
It's a scanner artifact. You can see the slight diffraction caused by a piece of dust as a RGB stripe. Clean the prism assembly and lens and it should go away.
I have scanned the image at an Epson 850, i can’t see it on the negative, but it’s so small so i thought i need a powerful magnifying glass. I moved the film inside the film holder and the stripe appeared at the same place.