Exposure difference in C41 film

Hi All, I noticed a blocky chunk on the left side of one of my negatives that had a difference in exposure, and I'm wondering if it looks more like fogging, or something to do with how I developed it. I have been using the Unicolor press kits in my Jobo CPA-2.

Here is the "problem photo:"


Here is a photo from the same roll and same development batch that doesn't have this problem:


So I'm trying to figure out what it could be and how to avoid it next time. Fortunately, when I am shooting something I care about, I tend to bracket/shoot multiple rolls/stocks, so I still have some usable shots from this location.

I just figure if there's something I can avoid doing that is causing this, I would like to know about it.

thanks!

There is what appears to be a processing streak down the left side of the top photo.

PE

How does this happen and how can I fix it?

I have no idea how it was processed or what the problems might be. Sorry.

It could even have been a kink in the film.

PE

I'd first check if this appears on the negative by examining it under a loupe. If it doesn't, it could be light leaking under the negative during scanning. If it is on the negative, I'd say it's likely to be a light leak in the camera. If you look at the attached crop where I've pumped up the saturation and contrast, there doesn't seem to be any colour cross-over in that area. The streak seems to be similar to the brighter areas along the top edge of the frame. Did the problem frame sit ready to be exposed for significantly longer than the other one, and hence next to a leaky back? That could explain why you have the mark on one frame and not the other. Have a good look at the light seals. I've also had light streaks caused by kinks when I loaded the film onto the processing reels, but they are not usually this shape. Another possibility is that part of the film was unevenly processed. For instance, if a drop of developer ran down that part of the film before the main processing began, but it doesn't look like a mark made by chemicals to me.

Great photo, by the way

Agreed!
Great photo.