5DII 24-105 photos blurred - is there a 'golden' range of SSs for using IS?

Started Nov 20, 2012 | Discussions thread
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Phil1 Senior Member • Posts: 1,371
5DII 24-105 photos blurred - is there a 'golden' range of SSs for using IS?

5DII, 24-105,@70mm, f4, ISO400, 1/180, 100%

Apologies!  Stupidly I had posted this in the wrong forum (Open Talk) when I should have posted it here. I had several thoughtful replies but then realised that the 1D/5,6D forum would be more apporpriate.

Several photos with the above combination look very blurred. I focussed (centre point) on the 3rd log in from the left (the large silver one). The logs in front of it and behind it are even more obviously OOF. The silver one is the least blurred which I take to mean it is the one in focus. Naturally at @100% this is a very small portion of a much larger photo.

I would have thought that at 1/180 it should be much sharper.

I'm sure I had the IS on, but it this the cause of the problem? I've read that using IS at the wrong shutter speeds can be counter productive.

I don't think it is front or back focus issues as I've checked the MFA setting and anyway the silver log I focussed one is the least blurred one there.

It's all a bit of a mystery as I usually focus with the centre point and then recompose, waiting for the focus confirmation beep and light.

I've checked and the 5DIII is in focus priority mode as it won't fire until focus has been achieved.

My initial suggestion came from the M43 forum where, apparently, at certain intermediate shutter speeds the 'shutter shock' (they have no mirror of course) is thought to cause the very light IS lens group to move at a frequency where the IS can't cope. (It seems the IS elements have to be very light to increase reduce focussing speeds).

I was hoping that moving from a 5D (original) to a 5DII would give an increase in perceived sharpness but it hasn't happened as far as I can see.

I shoot in RAW and use unsharp mask conservatively. Is there anything else you can think of that I could look at to improve sharpness?

I'm mystified and really would appreciate some more advice! Anyone else have similar problems?

Many thanks


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