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05-05-2010, 04:48 PM   #1
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Focus drive not engaging the lens?

In short my K10 AF might be breaking and I have a lens on now where it works but if I switch lenses it may never come back

Has anyone had a similar problem? Know how to avoid or fix it? Please help;

The story:

I've been on vacation with the K10 and too many lenses, quite often ripping lenses off and slamming lenses on to the camera in a hurry, and took one fall on a trail where the end of a long lens took a knock on a rock (which could have torqued the bayonet mount I guess).

Two days ago I put on my 17-70 Sigma, went to focus and was greeted with the sound of the focus drive motor in the body spinning crazily, but the lens was not engaged and would not focus.

Concerned it was a software glitch or something I rebooted the camera, removed and replaced the lens. That time the problem went away and the lens' focussing worked.

A little later (and after doing a lot of catch-in-focus shots with another lens) I had the same problem again, but this time no amount of cycling power and putting the lens on and off, or trying other AF lenses, fixed the problem. GAH!

I looked at the mounting ring assembly on the body of my camera,

and wiggled the small squarish metal tab which can be found on the inside a few degrees counter-clockwise from the red dot. Mine is a bit scratched and bent (but not much) compared to other k-mount plates. I tried to push it back flat-ish. This did not fix the camera.

I took my finger nail and ran it up under the leaf spring beside the metal tab (changing nothing as far as I know), and poked at tab once more. This seems to have fixed the problem for now.

I am afraid to switch lenses atm however, lest I lose my AF drive.

Anybody experienced this before? basically the AF coupler may or may not engage depending on how you hold your mouth when you do it.

Is that little square tab near the red dot the culprit?

Any help much appreciated.

Jesse

05-05-2010, 05:04 PM   #2
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Check your AF/MF switch. It might have been bumped and is engaged enough to spin the shaft, but not enough to engage the lens.

To be sure, move it to each position a couple times.
05-09-2010, 12:03 AM   #3
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QuoteOriginally posted by alohadave Quote
Check your AF/MF switch. It might have been bumped and is engaged enough to spin the shaft, but not enough to engage the lens.

To be sure, move it to each position a couple times.
I did try that. So far I haven't had the problem since the OP, but I'm being very ginger and minimizing changes. Missed some great shots because I was too chicken to change lenses.

I also have a couple of junk sfx bodies, so if it all goes I could try some home repair.

Thanks again.

J
05-09-2010, 12:59 PM   #4
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Sounds like your camera AF drive tab in not engaging the lens AF drive slot. This tab is spring loaded and is compressed flat to the camera mount when you attach a lens, and then 'pops' out when the lens is fully lined up. This AF tab is located on the other side of the camera mount from the red dot. It looks like the tip of a small flat blade screwdriver. Does this tab move in and out easily when you push on it with your finger?
The pin that is near the red dot is the lens lock pin. Is that pin bent? Maybe your lens is not mounting properly, and the AF is not lining up.

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