Is 650D, a APS-C body, compatible with EF 600 mm f/4 lens? In other words can i use a 600 mm EF lens with my 650Dbody?
Yes EF lenses mount on both full frame and apc bodies. The apc body simply doesn't see all the glass corner to corner so the EF lens is slightly cropped. I do recommend EF lenses as they adapt easily to other bodies as you upgrade down the road, being they are larger.