Thanks für your answers but a few questions are still left:
Primos are not always spherical? Are there special adapters to make a spherical lens anamorphic?
@audiris
But anamorphic lenses are not as fast as spherical lenses, so you have to use faster film and the advantages of the bigger area of the negative are gone - am I wrong?
Mostly I only see the copy of a copy of a copy... in the cinema, not a good quality, but I still have the impression, that films shot with Ultra Primes are sharper than those filmed anamorphically. On DVD I only analyze the flare and distortion.
Every time I see masterpieces of cinematography shot anamorphically (Apokalypse Now, Leon...) I'm shocked by the flare, the distortion - I hate this look :(
You can always reduce the sharpness but you can never increase it, so you can put a Softar, "vaseline" (you know what I mean?) or a black net in front of a Ultra Prime when you need it and you still have the mechanical quality, the flare-prevention - is it really necessary to use "cheap" equipment in 35mm (in big productions)? Ok, but you said it already, people's preferences differ, I for myself don't like unsharp pictures, flare, Video, >35mm, shaky hand-camera if it isn't really necessary (exception: James Ryan), Dogma 95...
@SamWells
Ok, most of the scenes, but only in special situations, because there are no Zeiss 10x Zooms (after "2001"). Cooke = Taylor-Hobson? But how do they earn enough money for the newest machines and developements? Zeiss is very innvovative (so is Leica), aspherical lenses, floating elements, special coatings..., I've seen the production-facility from Leica, really impressive! When they are really as good as the newest Zeiss/Leica-constructions, they are welcome at "still photography"!