IS Query

[David Morison]

At present I have an EF 400mm f5.6L which I use mainly for bird photography. I really don't have any problems with camera shake in terms of image blur because of the higher shutter speeds I use, however when trying to focus on a very small object the exaggerated movement associated with a 400mm lens means it is difficult to keep the AF spot on the target which results in quite a few oof images. I also use an Olympus E-M5 with it's 5 axis in-body IS and this stabilises the image in the viewfinder (electronic) very well, even at 400mm +, to enable me to keep the AF spot in place. Am I right in assuming that a Canon IS lens will have the same beneficial effects with the optical viewfinder? Excuse my ignorance on this but I have only ever used IBIS.

Many Thanks

David

[Hereford_EOS]

Re: IS Query

Useful read HERE

[mikep]

Re: IS Query

Hi David

In essence, you are correct. IS has 2 benefits...
The first is to produce sharp images, where originally a lower shutter speed would have had a blur beccause of camera movement etc.
The second is that the image in the view finder (or rear screen if using live view) will appear more stable, enabling better accuracy in placing the focus. This does not necessarily have any impact on the sharpness of the end photo.

In every day use, the benefit of IS will be much less, or non existent when the reciprical of the shutter speed exceeds the focal length... i.e. 400mm focal length used with over 1/400 second TV, however, it will still keep the image in the viewfinder more stable, regardless of TV.
So your image in the viewfinder will be more stable even at 1/3200, although using that setting produces the same end result with and without IS.

IS is no replacement to good holding/panning technique, and the perceived benefit therefore also varies with the ability of the photograper! A good technique 'could' allow a sharper shot at 1/200, whereas even with IS a rubbish technique 'could' still cause an OOF/unsharp shot at 1/500 upwards etc.

Hope that's clear! Probably not though!

Mike

[Thndr_strck]

Re: IS Query

And remember some IS systems will try fight against your panning if not set right.