To use IS or not...

I've heard that when an IS-capable camera is mounted on a tripod, it's best to shut the IS off.

How about situations where you're shooting in bright daylight - hand held, very steady of course - at say, a 100mm equivalent focal length at a shutter speed of a 250th of a second? Is it better to shut the IS off for that particular shot?

Has anyone experimented with this?

On my canon P&S the only time I turn mine of is when using a tripod

I keep the IS turned off when on the tripod, as recommended, and only use it shutter speeds fall below 1/125 while hand-holding.

That's not a particularly fast shutter speed for a 100mm lens--especially if it's really a heavy 70-200mm zoom. Did you know that hoary old thumbrule only applied to images enlarged no more than 10x?

Most people can't really hold a camera steady enough to use that thumbrule for images enlarged over 10X and people who can most often don't. Most of the "my lens is soft" complaints (when people are looking at 50x on their monitors) are really subtle camera shake.

Yes, use IS when you're handholding the lens.

Leave it on unless the camera is on a very solid tripod. The SX1/SX10/SX20 at 100 mm correspond to a FF DSLR at 560 mm and that needs a shutter speed of not less than 1/600 sec. to get acceptably clear images as a rule. Note "acceptably" - going to an even faster shutter speed will give you better, crisper images. Also note that that shutter speed assumes you're using the EVF not the LCD screen. If you're using the LCD screen, and consequently holding the camera with bent, unbraced arms better add a couple more stops of shutter speed to whatever you'd need otherwise.

Jon wrote in post #10948816
Leave it on unless the camera is on a very solid tripod. The SX1/SX10/SX20 at 100 mm correspond to a FF DSLR at 560 mm and that needs a shutter speed of not less than 1/600 sec. to get acceptably clear images as a rule. Note "acceptably" - going to an even faster shutter speed will give you better, crisper images. Also note that that shutter speed assumes you're using the EVF not the LCD screen. If you're using the LCD screen, and consequently holding the camera with bent, unbraced arms better add a couple more stops of shutter speed to whatever you'd need otherwise.

Fair enough and your point of view make sense but what about NOT using IS on a tripod. What's the logic behind this theory?

Wowsers wrote in post #10950312
Fair enough and your point of view make sense but what about NOT using IS on a tripod. What's the logic behind this theory?

The first generation of Canon IS was not able to discern that the camera was fixed to a tripod, so it tended to wander about trying to find steadiness...creating its own unsteadiness. Generation II and III versions of IS can discern they 're on tripods and don't attempt to adjust themselves further. However, while IS is on it's still drawing power--so Canon advises turning it off on a tripod for that reason.

With regard to handholding with IS, one reason one might turn it off is that some people have reported problems using IS to follow subjects that move erratically, such as soccer (futbol) players--the camera interprets the erratic movement as severe shake and fights to control it. Of course, in those situations they are also using the highest possible shutter speeds.

Basically, the camera's gyros are still looking for vibration and end up picking up their own motion, which introduces a feedback loop, as the lens tries to compensate for non-existent vibration.

Jon wrote in post #10950384
Basically, the camera's gyros are still looking for vibration and end up picking up their own motion, which introduces a feedback loop, as the lens tries to compensate for non-existent vibration.

Again....that makes a lot of sense.

So when i'm doing macros with a tripod with my SX20, IS should always be off to make sure the camera does not try to compensate for shake that isn't there in the first place?

Right. But use your remote or self-timer if possible so the tripod can settle down from any jostling you might have given it.