Originally posted by Ira High resolution sensors, quality lenses, and computer post-processing has negated many of the concrete requirements of using a particular focal length in a given situation.
You forgot the "pixie dust" factor, Ira. But since you feel that way, I'll be happy to take your ST35/2, ST50/1.4, and ST105/2.8 off your hands for a nominal fee. Mmmm, better throw in the ST85/1.9 also. Always glad to help.
@OP,
How to make a lens on an APS-C camera act wider:
* Screw a sucky wide adapter in front of the lens. Ewww...
* I read that backing up 10 ft / 3.3m is like going 1.5x wider.
* Use wider glass. Anamorphic cine lenses are great!!!
* Shoot into a convex mirror. Objects may be closer than they appear.
* Get a 645 or 6x6 cam. Insert a 135 cart. Sprocket-hole panos!
* Shoot an ordinary shot. Tastefully make it wide-angle in PP.
* Rewrite the laws of physics / optics. Anyone can now.