Originally posted by stewart_photo Part of the reason may rest in the two sentences found on page 67 of the owners manual... "The Shake Reduction function will not fully work when shooting at slower shutter speed, for example when shooting a moving subject or night scene. In this case, it is recommended that the Shake Reduction function be turned off and the camera used on a tripod." In other words, a limitation of the shake reduction system.
So, if we ignore slower shutter speeds (as in the ambient light situations you mention, Richard) and just focus on normal flash situations, the remainder of the reason may rest in the notion that flash is reasonably fast enough to freeze any movement, making shake reduction pretty much unnecessary.
stewart
Well, I've been shooting at about 1/15sec with the flash in a room with light fixtures. The short duration of the flash certainly freezes any subject motion but the light fixtures would be blurred by camera shake without SR enabled. At least in my old shaky hands. I could shoot at a faster shutter speed (up to 1/180sec) but that would defeat the idea of capturing the ambient light. The result would be an obvious flash picture, less natural looking.
As it is, my set-up does work with SR, with the flash mode set to Flash On. I guess users of off-camera Pentax flashes have to live without SR if they use the Wireless flash mode. That doesn't make any sense to me. As for the manual, obviously SR will have no effect on freezing subject motion, only on reducing the effects of camera shake. I have used it to good effect in hand-held night scenes and other low-light situations (without flash). That includes scenes with subject movement. Anything moving (people, vehicles, etc) tends to be burred but static parts of the scene are sharp. This is rather contradicts what the manual suggests.
Richard