Quote Originally Posted by Buddhakon
will there be any short comings using an EF lens since the image sensor on the XSI is not full frame?

Only when using wide-angles. A full-frame wide-angle lens (such as 16-35/2.8L) is less efficient than an EF-S lens of similar focal length (such as 17-55/2.8IS) when using a crop body like the XSi, since the 16-35L is designed as a wide-angle lens, while the EF-S 17-55 is designed as a normal lens. That is why the EF-S 17-55 can have a larger zoom range and IS while still costing less money.


Quote Originally Posted by Buddhakon
I was told that using a non EF-S lense may have black spots in the viewfinder...I don't know how but thats what I've been told...

It is not true that a non-EF-S lens will cause black spots. The black spots in the viewfinder are most likely caused by dust that got inside the camera during a lens change and landed on the focusing screen. The dust visible in the viewfinder wil not show up in the pictures.