# IS vs Shutter Speed



## BeenThere (Jan 18, 2016)

I've been shooting BIF handheld for quite a few years. Recently I am using a new telephoto and have mostly shot in IS mode 3. I am wondering if there is a high shutter speed at which sharpness begins to suffer if IS is on? For instance, shooting at shutter speed 1/2000 with 400mm handheld would IS be more likely to help or hurt sharpness? Anyone know the frequency response of Canon IS on their newer telephoto lenses?


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## candc (Jan 18, 2016)

BeenThere said:


> I've been shooting BIF handheld for quite a few years. Recently I am using a new telephoto and have mostly shot in IS mode 3. I am wondering if there is a high shutter speed at which sharpness begins to suffer if IS is on? For instance, shooting at shutter speed 1/2000 with 400mm handheld would IS be more likely to help or hurt sharpness? Anyone know the frequency response of Canon IS on their newer telephoto lenses?



I don't think mode3 ever hurts. It only compensates perpendicular to the panning direction at the time the shutter is engaged.


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## neuroanatomist (Jan 18, 2016)

I've tested IS on vs. off at fast shutter speeds with my 600 II and found no impact on sharpness, provided you allow the brief time needed for the IS to fully activate (i.e. if you just mash down the shutter button, having IS on is worse – that's true at lower shutter speeds, too.


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## BeenThere (Jan 18, 2016)

neuroanatomist said:


> I've tested IS on vs. off at fast shutter speeds with my 600 II and found no impact on sharpness, provided you allow the brief time needed for the IS to fully activate (i.e. if you just mash down the shutter button, having IS on is worse – that's true at lower shutter speeds, too.


Were your results handheld or tripod mounted? If you found no difference in sharpness, did you ultimately leave IS off in this situation?


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## neuroanatomist (Jan 18, 2016)

BeenThere said:


> Were your results handheld or tripod mounted? If you found no difference in sharpness, did you ultimately leave IS off in this situation?



I tried both tripod mounted and handheld, shooting an AI QA-77 chart (the kind Bryan/TDP uses, a modified ISO 12233 chart). I leave it on, since during shooting I'll often drop the shutter speed for a lower ISO when birds are perched.


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