In M mode the ring controls shutter time, pressing the Av button
tranfers control to the aperture. A little awkward, but you learn =)
On the istD, the front ring controls the shutter time, the rear one
controls
the aperture value. I haven't handled a Ds, apparently it only has one
control wheel, so I don't know how it seperates the control function.
I have this tiny lens and love the handy combination it creates. It
is a bit fiddly to handle when changing lenses and the focus ring can
be hard to find.
Nevertheless, I look forward to the other pancake lenses that Pentax
is planning, these will perhaps cover the 28 and 50 mm form factors...
Here's an example photo; late afternoon light, 1/250 f/6.7.
http://web.telia.com/~u40938461/PinkyPentax/Various/PancakeWall.jpg
Bertil
