Quote Originally Posted by m1tch View Post
Thank you so much for your help on this I think I kinda get it, I will have a look for that value when purchasing, I guess I could also make it from 6 1D lenses for example?
That would work. One Dioptre is a common size for supplementary close up lenses (it looks like that is what you are using already) the most common being the Canon +1 lens with a 58mm thread.

They seem to be available in 1, 2 and 4 Dioptres but not 3.

The adding of Dioptres method technically only works for lenses very close together but I think all of yours will be close enough for it to be a good approximation.

Something I learned here was that if you put a positive and negative lens together, you can create a degree of zoom by moving them apart.