Back to the Hasselblad and the WLF this time, but the problem persisted. This gets filed under “always check your film back”. Turns out some of the seal for the darkslide had worked itself loose and crept into the image area. Looked a lot like film emulsion actually, so I’m not sure if it’s the seal itself or maybe some 30 year old film that was stuck in there. Will have to run a light test to confirm if the back will still functional. You can see the masking in the top right of the 3rd image, which showed up in every image. It also caused light leaks on several of the shots as it got between the darkslide and the film. Thankfully I was able to Photoshop it out of the others. You can bet I’ll be checking my holder before I load film the next time!