question about the image stabilization lenses

This may be completely obvious but i'm asking more for just a confirmation -

When using a canon lens with image stabilization - and your camera is on any sort of automatic setting - the lens will communicate with the camera letting it know it it can knock it down a couple stops... correct?

ie - it will take into account that an image stabilization lens is being used and adjust accordingly?

Nope. It'd be nice if the cameras were that smart, but as it stands now they behave the same whether the lens is IS or not...the difference is in the result.

just curious...why would you even want it to do that?

ahhh ok ok im getting it - it still uses the slower shutter speed - but it compensates for the movements you may make during that slower shutter speed - helping reduce blur.

i guess i was getting confused because a lot of descriptions describe being able to take shots two stops slower... but really you're taking them at the same speed just getting better results because of less shake....

and if you put it on manual - you can make it go two stops slower than normal, and get a better exposed picture than you usually would in low lights?

just trying to wrap my brain around all this. heh

well thats kind of exactly my question jaert - a lot of descriptions talk about being able to take photos at two stops slower - which confused me because, like you said, why would you want to?

Shooting at slower stop with good results with IS or without IS means that the subject must not move, and who knows if it does My experience is that subjects are moving 90% of the time..
ONLY for portraits and other not moving subjects and with long 300mm, 400mm,500mm and 600mm lenses I think IS is really useful IMO.

Its not that you get a better exposed picture, the picture will be exposed just the same as if it was a non-IS lens (based on your shutter speed, aperture and ISO as normal).

What you get is the same exposure, but the stationary objects should have less camera shake visible if you are using a slow shutter speed. Moving objects will still suffer from blur though......

IS reduces camera shake when hand holding. If there is plenty of light you can set a very fast shutter speed, there is no time for your hand to move etc. and the picture is nice and crisp. Trouble is if its a bit dark, even with the maximum aperture, you can't always get a quick enough shutter speed and still be correctly exposed. In that case there is a good chance that tiny natural movements of your hand will move the camera enough to make a slight blurring of the image. So you can switch on IS and it will try to cancel your hand movements and so make the image nice and crisp again. The camera settings are the same, still correct exposure, but the risk of camera shke is reduced. It is usually stated that you can hand hold without significant camera shake at about 2 shutter speeds slower (2 stops less) than you can without IS.

an esample were IS really helps is to alow a slow shutter speed to produce prop blur in a plane or copter a 200mm lens on a 1.6 crop needs around 1/500sec to avoid shake that would stop pro blur but with IS you can drop down to around 1/200 get prop blur and no risk of camera shake.
Rob

I like to shoot wildlife either at dawn or dusk. Since there is less available light at those times and wildlife usually requires that I shoot at long focal lengths IS enables me to get photos that I would otherwise possible not get at all.

At 300mm, rule of thumb is that I need a shutter speed of at least 1/300 sec to avoid a blurred photo due to camera shake. Well, its not uncommon for me to only get proper exposure at speeds much less than that, say 1/90 or so. Most of the time the IS will allow that. Of course, as mentioned, that does nothing for moving subjects.

I just created a simple diagram to help those wondering about image stablization and their function. I hope this helps some people who are just figuring these things out.

thats really good MagentJoe .
Rob

Hey Joe...that chart reversed would be a pretty good explanation of how subject movement is less of a problem the further the subject from the lens...the exact opposite of shake.

Thank you JaertX. I was thinking of that in the chart but I wanted to keep it simple to understand. I was hoping that someone would bring that up!

Image Stabilization really only makes sense in longer focal lengths. For shorter it's better to have wider aperture.

i use my IS because, esp at full zoom, im one shakey bastard!
-zacker-