gfen <[EMAIL PROTECTED]> wrote: >Is it then possible that USM lenses will be AF backwards compatable with >any body that doesn't not support KAF3?
It's certainly technically possible, but the real question is whether it's economically practical. You'd have to have both conventional and USM focusing systems in the lens and have a mechanism that disconnects the conventional drive mechanism when it detects power at the power zoom/USM contacts. This would increase the price beyond what USM in itself would add. I suppose a manual select switch would also work but it seems inelegant and would be annoying for those who have an AF body with the KAF3 mount and one with KAF2 and used the same lens with both. Automatic detection and switching seems the way to go and it might just be too costly except on big dollar lenses. -- Mark Roberts Photography and writing www.robertstech.com
