[Brightcolours]

[quote name='wim' timestamp='1285257896' post='3177']

Yes, I realize that. I just wonder in how far the APS-C, APS-H, and FF sensors and circuitry are really prepared for this. There are a few Canon "compacts" which use USM, so therefore it should really be possible <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />.



Kind regards, Wim

[/quote]

All the sensors now can deliver 30fps... so they should be up to the task. It is not the USM that makes the fast contrast AF possible, but the implementation of motor electronics commands. The lens motor type is not important, really. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/blink.gif' class='bbc_emoticon' alt='' />



So... three things possible:



New mount with contrast detect AF only lenses, old lenses (with mount adapter) offer slower AF.



New lens "models" which offer both the PD-AF command set and the contrast AF command set, old lenses offer slower AF with contrast AF.



PD-AF done on sensor level, no need for contrast AF and old lenses (with mount adapter) offer fast PD-AF still.