what`s an autofocus lens?

[MEXICAN GIRL]

what`s a zoom lens? what`s the diference?

[snibbetsj]

An autofocus lens is a lens with a motor in it which responds to commands from the camera to achieve the (hopefully) correct focus. These can usually be manually focused as well.

A zoom lens has a range of focal lengths (such as the 70-200 f4) instead of a single focal length (such as the 50 f1.4), which is known as a prime lens.

[MEXICAN GIRL]

can the zoom lens be used with the rebel xt?

[snibbetsj]

All Canon EF and EF-S lens can be used with the XT. Third party manufacturers such as Sigma, Tamron, Tokina, and some others, produce lens with EF mounts which can be used with your XT. There are adapters for others lens, such as Leica, which allow them to be used (in manual focus) on the XT. Basically, any lens which is advertised to be an EF mount will fit on your XT.