IS Question

[roqdawg]

While it has been well documented that an "IS" lens lets you shoot at shutter speeds several stops lower than with a "non-IS" lens, and therefore in lower light, I have never seen a comment on "IS" performance on normally acceptable real world shutter speeds in normal daylight.
For example: If shooting at 1/500 at f5.6 with a 200mm lens, would an "IS" lens with 3 stop capability give you a result comparable to shooting at 1/4000 at f5.6 and therefore much sharper (assuming the subject is stationary)?
Tom

[august23]

Not entirely. IS in broad daylight still has it's advantage of stopping as much shake as it can from your given hands. It's more efficient in low-light situations, non action that is, where you need maybe another stop or two longer to let enough light in.

[august23]

For example: If shooting at 1/500 at f5.6 with a 200mm lens, would an "IS" lens with 3 stop capability give you a result comparable to shooting at 1/4000 at f5.6 and therefore much sharper (assuming the subject is stationary)?
Tom

And you have this backwards. IS would help you in the other direction. If you were shooting at 4000 without IS, you could get a similar result at 1/500 WITH IS.

[roqdawg]

And you have this backwards. IS would help you in the other direction. If you were shooting at 4000 without IS, you could get a similar result at 1/500 WITH IS.

That is basically what I asked....just turned backwards. So you are saying an IS lens at 1/500 would be the comparable to a non IS lens at 1/4000 for non action scenes.....also...from your first response, I'm comfused as to why you say it doesn't help sharpness wise in the "forward" direction...IE: giving three stops of additional sharpness on non-action with an already acceptable shutter speed.
Tom

[august23]

Sorry, I read it wrong, yes that's what I'm saying. IS won't make the picture any sharper than the glass elements in the lens will allow. What it will do is remove any user-made shake to blur the image. So in a sense, yes, the IS will help in the "forward" direction.

[roqdawg]

Thanks August23....I just thought it strange that I have only seen "IS" benefits discussed as helping in lower light situations, but absolutely no mention of giving any additional sharpness handheld in daylight use.
Tom

[august23]

Well truth is on my 17-55 I turn the IS off on purpose unless the lighting gets tricky. I find that in the day the IS just drains my battery. :(

[dicktay]

Roqdawg:
With a long lens ( like a 75-300 ) on a crop body it helps a lot more of the time, providing you are not shooting action. Low light is relative especially if you don't have a large maximum aperture lens.

It means you can can hand hold at slower shutter speed giving you more options on exposure control ie: ISO & aperture.

Here is an example:
Canon 350D (Rebel XT) with 70-300 IS lens.
1/50 @ F5, ISO 200, F=190 mm ( ~ 300mm equivalent)
Hand Held.
http://www.flickr.com/photos/34094515@N00/405462661/

[Lester Wareham]

While it has been well documented that an "IS" lens lets you shoot at shutter speeds several stops lower than with a "non-IS" lens, and therefore in lower light, I have never seen a comment on "IS" performance on normally acceptable real world shutter speeds in normal daylight.
For example: If shooting at 1/500 at f5.6 with a 200mm lens, would an "IS" lens with 3 stop capability give you a result comparable to shooting at 1/4000 at f5.6 and therefore much sharper (assuming the subject is stationary)?
Tom

You could take a look at my objective IS performance tests, for example this is for the 300mm f4L IS http://www.zen20934.zen.co.uk/photography/LensTests/IS_Tests/EF_300mm_f4L_IS_no_tc/index.htm

To cut a long story short with IS on the sharpness reached tripod equivelent at about 1/125 with a monopod and IS on Mode 2.

Handheld, Mode 1 would be above 1/250 to get to tripod sharpness. Nearly twice as sharp as IS off handheld at that speed.

I didn't do high shutter speed testing, but my expectation is you would just reach the optical limit of performance sooner with IS than without and saturate around that point.

Things might be more complx with zooms. Tests on the 24-105 showed a clear saturation close to optical performance with IS on or off the IS just making this a couple of stops earlier. http://www.zen20934.zen.co.uk/photography/LensTests/IS_Tests/EF_24_105mm_f4L_IS/index.htm

You can navigate around using the menus at the top of the pages to see more info.

Where you might have a problem with high shutter speeds is if you don't let the IS settle down before firing the shutter, that could degrade your shot. So I would say if you are shooting 2-3 stops above the conventional handheld speed you may as well turn the IS off.

[JohnnyG]

Well truth is on my 17-55 I turn the IS off on purpose unless the lighting gets tricky. I find that in the day the IS just drains my battery. :(

Really? I always leave mine on and I've never had a problem with the battery. Last year I went to the zoo with my 100-400 and left it on all day. I took over 250 pictures on the battery and it never ran down.

I wonder if there is a usage chart somewhere showing the battery with IS on and with IS off. It would be interesting.

I always leave it on for my 24-105 too!

[nicksan]

The battery on the 20D/30D/5D lasts for a long time.
I remember I was amazed about that when I used to own a 20D/30D and 17-55 IS. I had the IS on all the time (except when on tripod) and the battery would just keep on going and going like the Energizer bunny.

Outdoors I find IS to really be an non-issue.

Really, it's all about getting the shutter speeds to prevent any shake from coming into play. In daylight situations that's NEVER a problem for me. I still leave IS on for sake of simplicity's sake. Really, it's always on.