How to use correctly a Lomo Diana F+ and 35mm films?

Question

I have a Diana F+ Lomo (120 mm native). I recently bought the plugin to make photos with 35mm films.

I mounted the film correctly, but I had problems while taking photographs.

It was a 36 exposure film, but when I took the pictures and moved the film forward, advancing one by one every photo, I noticed I finished the film when the counter was on 18. When I developed the film, I had photos cut in two parts, with black parts too.

It happened on every photo I took, I moved the film too far forward. But I didn't know why, because I think I followed the index counting the photos. But at the 18th step it was impossible to go on, because I had already arrived at the end of the film.

Does somebody know what I did wrong and how to avoid this next time?

Answer 1

I'll suggest,

1. Check if you have set the N/P switch and using the mask correctly. N stands for normal and P stands for panoramic, which is essentially wider than the normal films. You will have spaces between films if you use P switch with normal mask.
2. The 35mm back won't stop you advancing the film, and it doesn't have a number for each shoot on the counter. Make sure you don't over advance the film after shooting
3. Check if you've reset the counter before start