Dark strip running on the negative

[Light Guru]

Thanks for your input!

I was pretty sure it's either a shutter / back or a mirror problem but it's inconsistent with the third frame.

I'll try with around 100ml more in the same tank and see if that helps.

Can't be a shutter problem and thinking about it for another minute it can't be the mirror either as the line is too sharp -- has to be chemistry.

Joe

The line on the second image is also curved so it's NOT the mirror. It is definitely chemistry.

 

[ienes]

All right I'm overwhelmed by the amount of feedback! Thanks for your help. I'll try with the hints you've pointed out and report back.