For sports you need fast shutter speed to stop action. IS will allow you 2-3 stops longer shutter for hand held shots, but it will not reduce motion blur.___JS..

IS really won't be an advantage when shooting moving subjects at high shutter speeds as in sports and bird photography, which you'll need to freeze the action. It will be an advantage when hand holding at low shutter speeds and shooting relatively stationary subjects. For that purpose I definitely prefer it over a tripod, which I rarely use until I'm doing several second exposures...

I often shoot whitewater kayaking from a moving kayak, no chance to use a tripod. By panning with the moving subject I can freeze the subjects motion and use the IS to steady my hand movements. If you are able to use very fast shutter speeds (which are necessary for some sports) then IS doesn't help..

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IS is just a tool. It's useful for somethings, but not for others, particularly not for sport and birding...

Those marketing IS are playing on your fears that a once in a lifetime shot might be ruined by camera shake. It won't do anything for sports where the subjects themselves are moving rapidly. But it will help in lower light conditions if you like a bit of motion blur. For wildlife using a 500mm lens a tripod is the sensible bet..

Spend your money on the Bigma or a trip somewhere interesting and just be aware of camera shake..

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Lanky wrote:.

Why if photographers got great pictures without IS is it stressed somuch today?.

Well, photographers got great images prior to AF also, but not many people want a DSLR without AF capability..

I am a budding young photographer and and very into mySports and bird (No animals in NZ) photography. All everyone seems tosay is the you need IS..

That's surprising, since for both of those types of photography, the required shutter speed to stop motion will also generally stop camera shake..

But my Dad, hobby photographer back in hisday still laughs at me and says I am wasting my money spending allthat money for something I can do with a tripod for half the price.So I guess my question is:.

Does a tripod do the same thing as IS?.

Yes, but only with much better perfomance. However, you will need to bring a tripod and use it, which can be very inconvenient. Do you really want to set up a tripod for every shot? How practical is this, especially since you want to shoot sports..

Out of 10 how important wouldyou say IS is for sports?.

For sports, maybe a 3. It is useful if you want to pan, or if you are shooting a fairly slow sport in low light with a long focal length..

How did all the photographer cope back inthe day without IS?.

The same way they coped without AF, without aperture priority, without a built-n light meter, etc. It can be done, but it was much more difficult..

And last but not least, would you suggest anamature photographer spends the money on a 100-400IS or saves somedosh for other things (car, other lenses, Windsurfing gear) and getsthe Sigma 50-500mm or something?.

Well, you are talking about a $1400 lens vs a $1000 lens. If you have enough disposable money to spend $1k on a lens, then generally you can afford a $1400 lens. You just have to decide if IS is worth the extra $400..

I have two IS lenses, and I love them. For me, I never use my tripod (it's a pain to set up), but I always use my IS lenses (including the 100-400L)..