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06-25-2011, 04:05 PM   #1
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K-5 contrast detect off by a good amount

This K-5 is off by quite a bit in contrast detect, but doesn't happen to all lenses. It's worst on my Tamron 70-200mm f2.8 where you can visibly tell without even zooming in that it is off in liveview. It goes right past the sharpest point. It goes very fast and locks quickly. Some of the other lenses I've tried are fine.

What would cause this? Newest firmware, reset settings.

Last edited by Eruditass; 06-25-2011 at 10:35 PM.
06-25-2011, 07:46 PM   #2
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Tried cleaning the connectors on both lens and camera?
My K-5's CDAF is ridiculously accurate. I wish the PDAF is half that good.
06-26-2011, 12:16 AM   #3
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QuoteOriginally posted by MaK5 Quote
Tried cleaning the connectors on both lens and camera?
My K-5's CDAF is ridiculously accurate. I wish the PDAF is half that good.

So do I.

CDAF is a lot slower than PDAF though
06-26-2011, 01:20 AM   #4
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QuoteOriginally posted by Smeggypants Quote
So do I.

CDAF is a lot slower than PDAF though
May be in case of Nikon but this is Pentax. Not a big difference in speed, day and night difference in accuracy.

06-26-2011, 01:27 AM   #5
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The liveview feed going into the Contrast-detection AF is What-You-See-Is-What-You-Get in terms of the final image capture. That's why CDAF is normally very accurate. Mine is - I use it to benchmark whatever settings I need to make on the Phase-Detection AF adjust menu for the same lens.

However, there is still hardware and software between the LiveView feed and the bit which tells where the AF motor needs to stop.

I suspect some adjustment is not quite right on your K-5, especially if you get the problem in more than one lens. May need a trip back to the service centre, unfortunately...
06-26-2011, 05:38 AM   #6
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My experience is that it either locks and is dead on or it won't focus at all. With my Sigma 70-200 HSM II, the thing will hunt and never lock. With my Pentax lenses it will either be very accurate or it will occasionally lock focus so far off that you cant even make out what you focused on. If it locks focus it is almost always as good or better that the phase detect AF.

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