I have a Praktica LB2 (35mm camera) I got for my birthday. I've noticed that on several frames, there is a black bar on the left side, always in the same location. It goes beyond the frame and onto the area of the sprockets. I've checked the interior of the camera with a flash light and have not detected any visible light leaks. I don't think its the shutter curtains because they are in a different orientation than the bar. The frequency at which these bars occur appears to be random. I have one roll with few or no bars at all. I don't know what could be causing them. My two primary lenses (Domiplan 2.8/50mm, Hanimex 35mm) appear to be functioning properly, in regard to the aperture blades. As you can see in one of the attached photos of two nearly identical shots (frame 6 and 7), the bar shows up on one frame but not the other. I could upload photos of my camera if anyone thinks that would be helpful in diagnosing the situation. I don't think it is my film choice either (in this case, i used Kentmere 400 film) but they have also shown up on rolls of Ilford HP5+ film.