K-5 contrast detect off by a good amount

Eruditass · 06-25-2011, 04:05 PM

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.

MaK5 · 06-25-2011, 07:46 PM

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.

Smeggypants · 06-26-2011, 12:16 AM

Originally posted by MaK5

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

Emacs · 06-26-2011, 01:20 AM

Originally posted by Smeggypants

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.

kittykat46 · 06-26-2011, 01:27 AM

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...

areidjr · 06-26-2011, 05:38 AM

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.

06-25-2011, 04:05 PM	#1
Eruditass Veteran Member Join Date: Jul 2009 Photos: Gallery Posts: 2,207	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.

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06-25-2011, 07:46 PM	#2
MaK5 Forum Member Join Date: Mar 2011 Location: Maryland Photos: Gallery Posts: 81	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
Smeggypants Veteran Member Join Date: Sep 2010 Posts: 1,536	Originally posted by MaK5 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
Emacs Veteran Member Join Date: Oct 2010 Location: Moscow Posts: 1,223	Originally posted by Smeggypants 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
kittykat46 Veteran Member Join Date: Dec 2007 Posts: 923	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
areidjr Veteran Member Join Date: Sep 2007 Location: Pittsburgh, Pa, USA Photos: Gallery Posts: 529	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.