Technical advice on focussing please! [D300 and 80-200 related]

Deckard

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Ben
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I wonder if any bright sparks have some advice for me.

I shoot my son's football matches and also any tennis tournaments I'm lucky to attend [e.g. Wimbledon] with my D300 and venerable one touch 80-200 f/2.8 lens.

I had the body set for focus priority in the past and found that it wouldn't shoot sometimes, clearly not having achieved focus, so swapped to release priority. As a result I get a minority of shots that are not tack sharp. I'm not talking full-on blurry shots and neither does it appear to have focussed incorrectly on something in the foreground or background. Essentially sometimes [and I don't know why] the lens fails to find focus leaving everything just slightly soft.

I had the lens serviced by Nikon last year and that has made no difference to the behaviour. The 80-200 is somewhat prone to back focussing but I have corrected this using -13 AF adjust.

My other settings are continuous focus, AF back button, AF lock on normal and generally use a single AF point somewhere around the centre. I've tried using 9, 21 or 51 3D focus tracking with similar results.

I suspect my ancient lens isn't helping, but I find it strange that most of the time it performs fine but sometimes doesn't and I can't stretch to a 70-200 VR so I was wondering if there was something else I may have overlooked.

Any bright ideas?
 
Possibly, especially when you mention tennis....



Check your photographs and see if the active focus point was over a single block of colour (as in solid white tennis shirt or xyz colour footie top). It might be that the camera hasn't found enough contrast to work the AF system accurately enough.

Btw this needs moving to Talk Sport!
 
Thanks for the move idea Mark, didn't think to put it there! Doh...

You may well be onto something there about a block of colour not having sufficient contrast to lock onto. I'll keep an eye out for any duffers and see if that's the case.
 
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