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Old Sep 24, 2010, 10:58 AM   #1
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Default How important is IS with a 70-200L?

I'm looking to upgrade my 100-300mm lens at my next chance (when I mention it and my wife doesn't immediately call her lawyer).

I don't see a lot of options at the 300mm focal length - the 75-300mm is not well received, and the 70-300mm seems to be OK but by the time it's closed down at 300mm its slow. Is this right? The 100-400mm looks nice, but I'd have to sell a kidney first, as this is all for fun, not profit.

This leaves the 70-200mm L series models. The f/4 model seems in reach price wise, but the f/4 IS model is cheaper than first buying the f/4 then upgrading later...

In theory the IS allows 4 stops of shutter speed increase, but does this hold true at the faster shutter speeds used with telephoto? In other words, does the IS work fast enough to be effective at 1/200s, or is it intended to cut the effect of mirror slap, etc., at 1/60s or less?
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Old Sep 24, 2010, 12:30 PM   #2
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Image stabilization is intend to compensate for motion blur due to camera shake. The primary source of camera shake is the constant feedback the human body's system of balance receives that permits us to stand upright. There are techniques you can utilize to limit camera shake, but remember that if the subjects you'll be photographing are moving, then the motion blur you need to worry about is from subject movement. Generally, if you use a fast enough shutter speed to prevent motion blur due to subject movement, you've probably got camera shake covered as well.
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Old Sep 24, 2010, 2:15 PM   #3
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What types of photography do you want to do with the lens?
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Old Sep 24, 2010, 2:53 PM   #4
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TCav- I guess that begs the question of why a 200mm focal length needs a 1/200s shutter speed - is it because of camera shake?

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Old Sep 24, 2010, 2:58 PM   #5
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with what you are shooting 200mm may be a bit short for the wildlife stuff, especially the birds. So you many want to consider that also when going with the 70-200mm f4L. And adding a TC will darken the aperture to about where the 70-300 IS USM is.
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Old Sep 24, 2010, 3:05 PM   #6
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Quote:
Originally Posted by iowa_jim View Post
TCav- I guess that begs the question of why a 200mm focal length needs a 1/200s shutter speed - is it because of camera shake?
Exactly. ... except that rule of thumb presumes you're working with a 35mm film camera. If you're using a 'Full Frame' dSLR, then that same rule applies. But if you're using an APS-H or APS-C body, then the angle of view is narrower so you must apply the crop factor to the focal length. So, for an APS-H body, the shutter speed should be at least 1/260, and for an APS-C body, the shutter speed should be at least 1/320.

And, again, if you're shooting sports/action/wildlife, you'll probably need a faster shutter speed anyway to prevent motion blur due to subject movement.
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Last edited by TCav; Sep 24, 2010 at 3:08 PM.
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Old Sep 24, 2010, 7:28 PM   #7
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So if my shutter speed is above a certain level, say 1/200 or whatever it may be, the IS no longer provides an advantage?

The corollary then - can a person take a picture at 200mm at 1/60 or less because of the IS, if the subject is stationary? Ergo, the IS trumps the 200mm=1/200s rule of thumb because the IS 'fixes' the camera shake that started the rule of thumb to begin with(?)

It's starting to come into focus now. Shooting sports as an example, we would not see a boost from the IS since the shutter speed is fast anyway. This makes the f/2.8 lenses so much more important for the pro sports photogs, given the increase in exposure for a set minimum shutter speed. But if we're taking a shot of a squirrel sitting on my fence or other slow movement situation, the IS will help dramatically with slower shutter times to increase the exposure.

At least, I think it's coming in focus. Am I on track?
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Old Sep 24, 2010, 7:31 PM   #8
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Yes. That's what IS is for: to counteract camera shake.
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Old Sep 25, 2010, 3:37 AM   #9
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For wildlife then the 70-200 won't be long enough. Take a look at the Sigma 100-300, that is a class piece of glass with a constant f4 and almost prime sharp. Sure no IS but if you work using the right tools (monopod, tripod or get the shutter speed up) then its a non issue. It also takes a 1.4x TC very well giving you 140-420mm at f5.6, yep, you lose some light but for birds I'm often at f8 or narrower (I shoot a 300mm f2.8 with a 2x TC unstabilised making 600mm f5.6).

As long as you don't want to shoot sports under the lights this would be a brilliant choice (IMHO). I have the 70-200mm f2.8 IS L btw and it is a lovely lens but if I didn't have the fast 300mm option already the Sigma 100-300 would be the winner for sure.
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Old Sep 25, 2010, 4:13 AM   #10
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Bad news: The Sigma 100-300mm f/4.0 is discontinued.
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