You know, I never really understood this. It’s exactly the same zoom, only less of it, surely? You could do the same thing with a Full Frame shot using Photoshop, just delete the bits you don’t want from round the edge. By that logic you wouldn’t need to spend a couple of grand on a super-telephoto lens, you could just cut rectangle out of a piece of card and stick it to the front of your kit lens.
Dunno. You could do those things, I suppose.
I am not sure there ever was anything ‘to understand’ as such. It’s just a conversion factor for a zoom convention, to apply it to different sized sensors, isn’t it?
I was just curious whether using that lens on that body would be equivalent to a genuine 200mm at the long end or something more, like 300mm equivalent (if, for example the body had a 1.5x crop factor).