I don't understand why one could not use long focal lengths in 35mm cinematograpgy. Or do you refer to the fact that lenses designed for large formats yield lesser resolution than lenses designed for small fotmats?
The minimum absolute size of a standard aperture is technically given. That is the reason that you won't find smaller apertures than you got at those shorter focal lenght lenses.
An alternative approach to looking for lenses with extreme small apertures is mounting a additional small aperture just in front of the front lens.
The most sound approach though is to mount a smaller (drilled) aperture inside the lens at the original aperture location. With some lenses that location is easy to access. You just have to find an appropriate way to fix that accessory aperture at that location.
Last edited by AgX; 11-17-2013 at 07:07 AM. Click to view previous post history.