Understanding/using IS.

mj4456

mj4456

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martin
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Recently acquired a 100-400l IS Canon lens, asked about the IS and ended up with more questions than answers, so, did a search on here and settled in to read. Am I right in my conclusions.
Bright days, short zoom range, fast shutter speed= no IS required.
Bright days, long zoom range, fast shutter speed= IS no1.
Dull days, all parameters= IS no1
Motorsport panning shots= IS no2
Is this the right direction hopefully.
 
That sounds about right, I guess. I always work towards the rule of if the shutter speed is slower than the focal length when hand holding then there will be camera shake, which is when it's time to put on IS.

So if you're getting 1/200th of a second at 400mm then there will be camera shake, unless you turn IS on. Although I don't know that particular lens too well but I assume it's got a pretty decent IS system on board.

As for panning shots, definitely mode 2 like you said - I don't know the ins and outs of how it works exactly but there's some funky mechanism in there that can tell when you're panning and disables the horizontal part of the IS.. or some mumbo jumbo!
 
IS is designed to reduce camera shake. It tries to compensate for small movements by the camera/lens when hand held. Here's my take after shooting with a 100-400 for 3.5 years....

- If your shutter speed is faster than 1 / (2 X focal length) then you probably don't need IS. e.g. at 400mm and 1/800 or faster I would probably not use IS.
- If you are trying to follow complex, rapid movements in your subject (e.g. BIF) then you should not use it.
- If you are trying to shoot with slower shutter speeds and want to keep the camera as steady as possible in all directions then use IS mode 1.
- If you are panning horizontally OR vertically then use IS mode 2.
- Do not use IS if you are trying to pan in a diagonal direction.

Exception - if you can pan/track very smoothly (in any direction) and your subject is moving across the field of view fairly slowly then you might get away with using mode 1, but be advised that if you swing the camera in an unsteady fashion then IS will try to fight you and you will end up with a jerky image in the viewfinder and mixed results.
 
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With my 100-400 I developed the following rues of thumb.

1. Am I taking the shot with a remote release?
Yes: Turn off IS.
No: Turn IS on.​
2. Am I panning?
Yes: Switch to Mode 2
No: Switch to Mode 1​
3. Am I on a tripod with a shutter speed longer than 1 second.
No: Leave IS on.
Yes: Switch IS off.​
 
Cheers guys, now I need to get out and practice.
 
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