Mark7829 wrote:
Shoot as least as fast or faster than the vocal length. At 200 mm = 1/200 of a second, etc., handheld....
Unless using that 200mm lens on a crop sensor camera... in which case you need 1.5X, 1.6X or whatever faster shutter speed. 1/300 to 1/320 with Nikon and Canon.
Practice and certain handheld shooting techniques might allow some people to use slower than the inverse rules suggests.
On a tripod, it depends on the lens. Check with the manufacturer. Some must have stabilization turned off when
locked down solidly on a tripod, or they can go into sort of a feedback loop that creates movement when there is none present. In my kit, I have a couple 28-135 lenses and a 300/4 that have this type of stabilization. These are normally handheld lenses for me anyway, so I've rarely had to turn it off.
Other lenses self-detect and turn off stabilization themselves automatically if and when they are locked down on a tripod (i.e., there is no movement), so there is no need to manually turn it off unless you just want to be sure. In my own kit two 70-200s, 300/2.8 and 500/4 all have this type of stabilization. Several of them I've used for over 10 years and don't recall ever turning stabilization off manually. But, again, the 70-200s tend to be handheld and the 300/2.8 and 500/4 tend to be used with the "loose gimbal" method mentioned above... in both cases leaving plenty to keep stabilization busy and out of trouble.
I agree that in-lens stabilization can be helpful stabilizing the viewfinder images...
But I disagree about it slowing focus... While it's possible that happens occasionally, a lot of the time I think stabilization actually helps focus speed and accuracy (i.e., it helps the camera "see" with its AF sensors, the same way it helps me see the subject in the viewfinder).
Stabilization does take a moment to occur... a very brief moment... and taking a shot too quickly might not allow time for it to "do its thing"... but focus and stabilization occur concurrently and most of the time by the time focus is achieved, so is stabilization... Still, as much as possible I start both focus and stabilization a bit before I take the shot, tracking moving subjects, for example.