Re: istDS v istDS2

[Adam Maas]

Godfrey, all ring type USM or AF-S lenses have this feature. The only 
other lenses that do are the Pentax ones and the Canon 50mm f1.4 USM 
which is the only micro-motor USM lens to be clutched (Pentax uses the 
same trick to get the feature). It's very useful, and I badly miss it on 
my Tamron 28-75.

-Adam

Godfrey DiGiorgi wrote:

I think you are describing the QuickShift feature of the DA and D-FA  
lenses, Patrice. Has nothing to do with the DS2. DA lenses on the DS  
and D act the same way. It usually does NOT work in AF-Continuous  
mode, however, as the body/lens is supposed to be focusing  
continuously. It's designed to work in AF-Single Shot mode ... lock  
in the focus on the half press, fine-tune focus with the focus ring.

Canon's USM lenses have this feature and call it "full time manual  
focus". It's an excellent feature.

Godfrey