IS How much is it worth?

[Prophet]

I use a Canon 70-200 f/4 L for most of my motorsport shots. Its not got the range but the clarity makes up for that IMHO.

I've also use a lens with IS and found the results to be fairly similar. Sure you may get a few more that are slightly sharper when your panning goes a bit squify but not enough to warrent double the price.

 

[aztechnology]

Not sure a lens at f2.8 really needs IS. I use VR [im a nikon user] but its the same thing i think, and to be honest on the f4, its nice to have, but on the f2.8 200mm zoom i have, its no use at all as its fast enough as it is.

For me anyways.

ColiN

Thing is though, that you might not want to use the f2.8. If you want more DoF or a better optical characteristic of *** lens, you could be closing a stop or 2. IS is really useful and if it's an option and you can afford it, I would get it every time.