Originally posted by RioRico No, SR doesn't reduce IQ at faster shutter speeds. I use SR at all times, except:
* As noted above, for tripod, timer, remote, etc.
* Handheld macro shots, where SR is ineffective.
* Old manual zooms, where I change focal length.
About the last: People have various calculations for setting SR for old manual zooms. What to tell the SR-bot for a Vivitar 70-210/3.5? I tell it nothing. I just find adequate light and SHOOT, like Back In The Day before we had stabilization.
Think of it this way: SR is most effective for certain focal ranges at slower shutter speeds. Falk Lumo has posted graphs showing the effectiveness ranges. Outside those ranges, SR doesn't hurt. SR *does* hurt if the camera is fixed, as on a tripod, or if the lens' focal length doesn't match what you've told the SR-bot. So if I mounted that 70-210 and told the 'bot that it was some fixed focal length, SR would diminish IQ the further I got from that FL. Thus I might tell SR that the lens was 200mm, then ONLY use it in the 190-210 range. If I zoom out to 70-100-135mm, it's time to switch SR off. Or else, re-enter the new FL, which gets to be a pain. Depends on how long I intend to stay at any specific FL, eh?
Sorry to take you to task on this, RR!
In the case of a vintage zoom, when the actual FL doesn't match the FL you input to the camera, you don't diminish the IQ, you merely reduce the effectiveness of the SR.
This holds true for all cases of the actual FL being longer than the entered FL. You need to be careful the other way round though: if the entered FL is more than twice the actual FL, you will indeed diminish IQ - in fact, you'll end up magnifying any camera shake.
As you're probably aware, I did some calculations regarding the best compromise FL for a vintage zoom, but I hesitate to post the link for fear of boring everyone!