28-70

[Joseph Tainter]

Hi,
The Don gave me the two above mentioned lenses to test drive over the
weekend. I'm presuming these are USM lenses. Right now, they seem to be
using the body motor for focusing. Do I need to upgrade the firmware to
utilize the lens's focusing motor?
Thanks

William Robb

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Bill, I would not update your firmware just to try SDM. If it is any 
faster than the shaft drive, you will need precise instruments to 
measure the difference. If you are shooting wildlife the quiet is nice, 
but otherwise I can see no advantage to SDM. I think it is mostly a 
marketing gimmick, like some other things Pentax has done because the 
competition has done them.

You can try the 50-135 just fine with the shaft drive. If focuses rather 
slowly by either method.

If you buy one of the DA* lenses, you can consider whether to update the 
firmware for SDM. I would like Pentax to bring out a firmware update 
that allows one to switch between shaft drive and SDM.

Joe