The advantage I do see to using in-lens servos on every lens is that it helps minimizes the number of mechanical couplings from lens to body. I don't know about anyone else's experience, but I know from my own that I've never once had a problem with an electrical coupling from lens to body, and that all the service work I have had to pay for has been either directly or indirectly attributable to the requirements necessary for mechanical couplings (iris actuation, metering sensors, focus drives, etc), other than the age and stiffness of grease on focusing helicoids in manual focus lenses.
I wouldn't want to see the nice compact lenses grow unnecessarily due to incorporating in-lens servos, but it would be nice not to worry about the iris actuator hanging out the back end. Godfrey On Nov 2, 2006, at 11:34 AM, John Forbes wrote: > My expectation (hope) is that on long lenses, USM will be > significantly > faster. On short lenses I don't need or expect much difference. > > I really don't see the point of USM on short lenses (because they > focus > fast enough), and I don't see the point on long lenses if it > doesn't yield > a speed improvement. > > As somebody pointed out (Shel?), it would be very nice to have > better low > light performance. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
