Aligning Negatives with the SA-21 Strip-Film Adapter (especially misaligned negatives)

The exact position of each frame on a strip of 35mm film can vary. That's especially the case where you loaded and wound the film manually.

(By being very careful, I could fit 39 or even 40 photos onto a roll of 36 picture film. I'd be careful not to unwind the film very far when attatching it to the take up sprocket. I'd shut the back of the camera, wind the film just a little (to get past the film that had been exposed to the light) and then take a picture that was one or even two frames before the place that Kodak, Fuji, Agfa et al expected you to be taking photo 1. You can't do stuff like that with auto loading cameras!)

My film processors would cut the negatives into strips of four photos. The first strip would have a random bit of leader film (sometimes including a bit of the file that was fogged at the time the camera was being loaded. The first real picture appears at a varying position off to the right of the strip of film.

I initially thought that the film adapter would mechanically think something like 'The first picture is probably 4mm from the left end of the negative. The second picture is probably 4mm+36mm+4mm from the left end of the negative...

If that were the case, you couldn't let the film adapter scan that first strip of negatives because they would never line up properly. Initially I got around this by putting the film in backwards. So in a strip with 'Blank leader, picture 0, picture 1, picture 2' I'd insert the strip with 'picture 2' going in first.

However, I've now discovered that the Strip-Adapter is a little more intelligent. If the leader is reasonably clean, it will try to align itself with the first negative. It seems that the Adapter (and the software) looks for edges on the photographs.

Note: If negatives are misaligned, the exact positioning can be quickly and easily adjusted in Scanner Film Extras; Strip Film Offset.

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