You're right if you use the same f/stop (relative aperture), but if you use the same actual aperture diameter, then it is exactly like cropping. 🙂palec said:If you take picture from the same spot but with longer lens, you have smaller depth of field and more obvious separation from background. It's not like cropping.
Taking the shot from the same spot is critical, of course, as perspective is a matter of distances only.
"One lens" is a useful learning experience I think. When I first got my M2 I had only a 35 'cron. The next year I got a 90mm too, but over the years I scarcely used it. The 35 was the universal lens... And later with the Minolta CLE the only lens I used on it for years was the 40 Rokkor, and I never really felt the need for anything else. Now that I have a 28 as well, I find that equally useful.
I still seldom carry a second lens when I go out shooting, though.