k20 no autofocus???

HI i hope someone can help? on a recent trip to new york with my k20 and 2 lenses (sigma 17-70& 8-16)the autofocus function in all drive modes stopped responding after one days shooting, both lenses are fine after checking on my k10 but my k20 refuses to autofocus with these and only these 2 lenses .I thought the autofocus motor had went on the body but it works fine with other lenses i have the latest firmware (1.4) but still nothing any suggestions ?? have tried all the usual remedies any help gratefully appreciated

Are they both HSM lenses?

yes both hsm both the latest sigma lenses!!

Clean the two square inner contacts of the camera mount and probably the mount of the lenses as well and try again.

Those are the contacts the HSM use to focus with so if they are dirty they won't have any power.

The K10D and K20D will AF with both SDM/HSM and screw drive lenses but whereas most Pentax SDM lenses have screw drive as well Sigma do not.

This means if your camera has faulty (or dirty) ultrasonic contacts it will default to screw drive but it can't with a Sigma HSM lens as there are no gears in the lens for it to use.

This is why the K20D is fine with your other lenses but not the 2 Sigma HSM lenses.

Hope that makes sense.

checked all possibles k10 works fine with all my lenses sigma and pentax HSM AND SDM all contacts clean, the 8-16 is only a couple of weeks old do you think it could be some menu setting i have changed i,ve checked but maybe im missing something!!??:

This isn't the case though.

The lens has a digital INFO contact and through that the camera gets information what function the lens has.
If the lens has SDM/DC/HSM the camera will know that and will use that as the mean to focus, if that fails it will never fall back to the screw-drive focus.

Well you could have pulled the AF option away from the shutter release but besides that there is no way besides the focus switch on the side of the body and some lenses to stop the AF.
But you can test this with other lenses you've.

If the normal lenses work then it's probably a dirty contact on your camera.
If it's the info contact then the camera will ask for the focal length if it doesn't it must be the SDM contacts.

If other SDM/HSM lenses AF OK on your K20D, it's not likely to be problem caused by a changed setting. If only screw focus lenses AF then the problem would seem to be with the SDM/HSM contacts and/or related circuitry. It could also be a faulty, under-charged, or under-powered battery.

You could try the following:-

1: Remove the battery from the camera for a while, refit it and try again.
2: Reset the camera to factory default and try again.
3: Try another fully charged battery and try again.

still no joy good old pentax !! guess its manual focus and back to the k10??? how much is the extended warranty on a k5 ??? any ideas, not prepared to spend a grand on a new camera body with only a 1 year guarantee!!awell such is life.javascript:;

If you buy your K-5 from a Pentax pro dealer then you will get 2 years warranty on it. You can find a list of dealers on the Pentax UK site.
SRS are a pro dealer and will give you free postage if you tell them your user name on PU.

How old is your K20D?

I would simply throw it that a product of this price range shouldnt have these problems and see what Pentax does.

I doubt if Pentax will be interested as the camera works with Pentax lenses. They would take the line that Pentax cameras support SDM but not HSM.

Pentax make it quite clear ion their manuals that they take no responsibility for non-Pentax attachments working. And why should they - they have no control over how well other people make the lenses or accessories.