You can use the whole EF range of lenses on all EOS film and digital bodies, regardless of the sensor size, the only difference being that on a 1.6 or 1.3 sensor body the focal lens appears to be 1.6 or 1.3 x longer respectivly, the actual focal length of the lens doesnt change, because of the Field of view (FOV) crop the smaller sensors dont see some of the outer portion of the lenses angle of view. EFs lenses (these have a white index mark for mounting as opposed to a red one on the EF lenses) will only fit the 1.6 crop sensor bodies from the 300D onwards. So that is the 300D, 20D, 350D and 30D. the 10D and earlier are not compatible with the EFs lenses, nor are any on the 1 series 5D or any of the film bodies. Bodies that are compatible with the EFs lenses have a white and a red index mark on the lens mount one for EF lenses and one for EFs lenses, this is so that people cant mount an EFs lens on a non compatible body as it would cause damage to the mirror.

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