Waste to use FF lenses on a crop frame Canon camera??? LOL Now I really have heard everything!!! One of he great strengths of the Canon crop-frame line is that it can use the entire family of EF-S and EF lenses!
Yes, it is a marketing angle. However, please tell me the point of a small camera like the 100D, when you have to put huge "full-frame" lenses on it to get decent optics, like the 70-200mm lenses or the 400mm lens?
Moreover, issues like corner softness and vignetting either 'go away' or become far less acute.L
-lenses are not supposed to have these "issues" and that is why they are so expensive. Thus, by using the "full-frame" L-lenses on a "crop-frame" camera, you just paid for something of which you cannot enjoy the benefit. Bad economy ... or simply wasting your money.
AND my 100-400mm becomes a 160-640mm equivalent!
No, your 100-400mm lens stays a 100-400mm lens. You just lose the great edge performance you paid for, 'cause of a reduced field of view due to in-camera, "hardware" cropping. (Honestly, do you really still believe that line of marketing hokey about the focal length increase?)
Ah, the silly, silly things people complain about!
You got that right, at least.