I got a lovely little Penti that came with two SL cartridges, loaded up 12 frames of Ektachome, and went to the fair. Once developed, the leader was clear, as expected, but the rest of the film was unexposed. I've done hundreds of rolls without mishap, and an inspection of the edge markings proved the film developed properly.
I rechecked the shutter and aperture, verifying that both were working properly. Another 12 frames were loaded and this time I opened the back a couple of times to verify the film was feeding correctly and everything looked right (I'm really liking the SL system). I also made sure to use all the shutter speeds, including bulb. This time everything came out as expected, including properly exposed frames and the fogged sections where the back was opened.
The only thing I can think of is that the first strip was loaded "backward", i.e. base toward the lens, emulsion toward the pressure plate. This seems very unlikely as the curl of the film would make this pretty much impossible, even doing it all in the dark. But there is really no other likely cause. Would one of the layers (antihalation?) prevent the film from exposing thru the base?
I rechecked the shutter and aperture, verifying that both were working properly. Another 12 frames were loaded and this time I opened the back a couple of times to verify the film was feeding correctly and everything looked right (I'm really liking the SL system). I also made sure to use all the shutter speeds, including bulb. This time everything came out as expected, including properly exposed frames and the fogged sections where the back was opened.
The only thing I can think of is that the first strip was loaded "backward", i.e. base toward the lens, emulsion toward the pressure plate. This seems very unlikely as the curl of the film would make this pretty much impossible, even doing it all in the dark. But there is really no other likely cause. Would one of the layers (antihalation?) prevent the film from exposing thru the base?