Can someone explain what cause this darker area on my picture

Quick update, I try to use rubber adhesive to cover up the hole on bellows, seems to works well. Anyways I just got a couple of 120 mailed to me today, will test and see how the result goes.

Happy new year to all of you. Cheers!

Looks like a light leak in the back to me. Pinholes tend to be more diffuse and star-shaped. Light is coming in close to the film as it moves along the pressure plate or right next to the take-up spool. Could be along the door, by the door hinge/lock or around the pins that hold the spools.

Folding cameras usually don’t strictly need light seals but I have one that had multiple leaks I couldn’t properly locate but that were eliminated by generously sealing off the back…

I just got my scan back from the lab and it seems like the like leak is gone. So I assume that the pin hole on the bellow is the cause of the problem. But now I have another question for the photo. I shoot 2 rolls of 1998 expired Kodak Ektarchrome 100 plus and the first rolls I rated for 25 ISO and the picture I got is heavily underexposed (Cross processing development) then I tried the second rolls and rated for 6 ISO the picture comes out a bit better than the first rolls but still underexposed. Considering that I have metered it to overexposed for 4 stops, is there any chance my lab just messed up the developing process or is it possible for the film to be this unsensitive to light.

Note : The lab adjusted the photo brightness to be visible and I think it is the cause of the fog on the image.

Pics form first rolls


Pics from second rolls

You never know what you'll get with greatly expired film, especially with color film. I've never tried slide film, but it isn't surprising the emulsion would be even more sensitive to age and storage conditions, as well as infamous need to be 'spot on' with exposure. I've seen old ektachrome slides, they are magical, sorry these didn't work out. I just got my own mamiya 6 folder, can't wait to try it out. Loved your photos!

I would suggest this is not a light leak, as the band on the negative is lighter. The edge of the band is also very straight and looks to me like some temporary obstruction at the focal plane. I'm not familiar with that camera, but would recommend a close examination therein.