OK, This might be a little off topic..... I see some of the posts saying that a 2.8 is really a stop slower on a 1.6 crop camera? I'm not sure how you figure that? Doesn't it still let the same amount of light go to the APS-C Sensor as it would a FF Sensor? ...And no, I really am not that smart!! And this is my next question.... Does the EF-S 17-55 F2.8 suffer the same thing as the EF lenses on an APS-C even though it's made only for the smaller sensor?neuro can probably explain it better but in simplest terms if you get a lens that works on both FF and crop let say a 17-40 f4L then fit it to each and frame the shot exactly the same so that both images filled each cameras view to the same extents. You would be standing closer to the subject using the FF and further away using the crop. Because you are closer to the subject you will have a shallower depth of field than the same lens taking the same shot on the crop since using the crop you are further away.
Thanks in Advance.
does that make sense?
since the EF-S 17-55 f2.8 only works on a crop body it behaves more like the 24-70 f2.8L so they are compared more to each other. So the 17-55 f2.8 doesnt suffer from anything
OK, That makes sense, since the 1.6 crop factor "brings things in closer" than shooting with a full frame......
Thanks very much for the Simple Terms!