Do I really need IS? Sorry for asking

[blakephoto]

Wow.... ok, well I currently shoot with a 400D but will be upgrading to either a 5D mkII or a 550D soon. Weight isn't really a problem for me, but sharpness I am rather picky about.

That 800 bucks is not gonna do you much good when you're standing there in the field, with a once in a lifetime shot coming up out of the grass, and not a tripod, tree stump, or fence post in a mile to lean on, all for the lack of that little "switch."

Don't take this the wrong way, but what photog worth his salt would be outdoors with out a tripod or monopod, saying that I lost a monopod while shooting in long grass once.

Well thank you all for your helpful comments, I'm rather swayed towards the non IS not only because of the cost, but the image quality is sharper if only slightly.

[DavidR]

If your picky about image sharpness maybe a prime is in your future, I sold my 70-200 2.8 non IS for the 135L. Saying that, when I purchase another 70-200 it WILL have IS.

[blakephoto]

Originally Posted by DavidR

If your picky about image sharpness maybe a prime is in your future, I sold my 70-200 2.8 non IS for the 135L. Saying that, when I purchase another 70-200 it WILL have IS.

I had a look at the primes and I currently use a 50mm for most of my shots, but I really like being able to zoom in on the subject without having to swap the lens or end up standing a foot away from them.

[Wilt]

Any time you need to hand hold ANY lens at 1/(FL*1.6) shutter speed on APS-C, IS can help. There are techniques that get you below that rule of thumb (like resting the camera against a rail or wall) but they still leave the camera subject to motion when you press the shutter button! And while it might look fine at 4x6", blow it up and you see the motion artifact. Short FL has nothing to do with NOT needing IS, the detail simply needs to be below a certain fraction of the frame size and the motion blur needs to be above a certain amount! To prove that point, here is a shot at 17mm on a hand held APS-C camera (all shots are section crops from full frame area)...
shutter speed, left to right: 1/25 (1/(FL*1.6), 1/12, 1/6, 1/3; top row no IS, bottom row with IS, when I had back pain just standing!

[Jason C]

As was probably mentioned already, "IS" does not help freeze a moving or living subject, a higher shutter speed is needed for that.

"IS" does help eliminate your input in hand holding your camera during a capture. "IS" is still a very helpful and useful tool, especially in your longer FL shots. It can also make the difference in getting that shot, or just missing it because of your camera shake.

Jason C

[Rubberhead]

It's seldom mentioned but many shots need an aperture smaller than wide-open. IS allows a photographer to shoot a smaller aperture than possible without it.

[pingflood]

Originally Posted by tkbslc

If you want to shoot at under 1/320 shutter speed without a tripod, then get IS. Otherwise, no benefit.

That's just poor advice. There's a huge difference between people when it comes to hand holding. I know some people who are shaky enough to need 1/250 or faster with a 50mm lens, and others that like myself can hand hold a 400mm prime at 1/160 well enough to get more than a few keepers. The "focal length times crop factor" is just a VERY rough ballpark figure, and much like the BMI should not be applied to individuals as some rule to determine what lens they should buy.

Not to mention, if the guy's shooting moving subjects, being able to hand hold at very slow speeds thanks to IS won't help any at all. Keep that in mind, too, before dissing out one liner advice.