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04-03-2013, 08:51 AM   #1
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DA 55-300 on K30-Intermittent Failure to Focus

The DA 55-300mm zoom on my K30 has been the workhorse of my outdoor shooting. Recently, this lens has started displaying a strange problem. I'll press the shutter button, the lens will try to focus, and the green focus light at the bottom of the view-finder flickers (no lock). Sometimes if I power off, pull the battery, put it back in, and power on, the problem goes away, but not always and I'm not even sure that process does anything--might be coincidence.

I'm going to try the lens on my K5 to see if the same behavior happens. I don't have a problem with the K30 and any other lens, just the DA 55-300.

Anyone have any suggestions, experiences or ideas?

04-03-2013, 10:28 AM   #2
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I have the same problem with two of my Sigma zooms: 70-200/2.8 (HSM) & 100-300/4. They seem to function fine after a day or two of rest but I can't depend on them to go reliably for both halves of a hockey or lacrosse game. Makes me glad I'm an amateur! Like you, I'm really puzzled.
04-03-2013, 10:41 AM   #3
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I've had this problem and after wiping, cleaning lens and camera contacts, it went away. Try removing the lens and cleaning contacts.
04-03-2013, 01:17 PM   #4
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I think I have figured this out. The lens also doesn't work on my K5, but other lenses are fine. This lens won't even manual focus. The focus ring is stuck tight. It's might fault, I fear. I experimented a bit with a teleconverter, one of the cheaper ones, and used the manual focus setting. I recall thinking it was turning hard, and eventually abandoned the TC. This was when my problems started with this lens. I think somehow my use of the TC messed up the screw-drive somehow and now it's locked up. It won't even turn in manual focus mode.

So…gotta think in terms of repair or replace.

Any advice would be appreciated.

04-03-2013, 03:09 PM   #5
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If you put it back on the k-5 and switched to manual focus mode, is it jammed at close focus or infinity or somewhere in between ? Look at the screen in live view to see this then compare with the lens focus ring markings and see if they match.
Also ,Try a jeweller's screwdriver directly on the lens drive and see if you can work out what's up with it.

Last edited by chromo; 04-03-2013 at 03:17 PM.
04-08-2013, 08:16 PM   #6
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I have had the same thing happen with my K-30 on several different lenses. I will take a few shots, it will stop AF when I half press the shutter, I turn off the camera and turn it back on and it keeps going. Seems to be particularly problematic when I am taking several pictures in rapid succession with refocusing every few shots. Hopefully 1.04 will fix this, because I think it has only been a problem since upgrading to 1.03.
04-09-2013, 06:05 AM   #7
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I'm convinced now the lens is just busted. I did use it for a day with one of the cheap teleconverters and switched from manual to AF as few times--and I noticed the Manual Focus seemed hard. Clearly the TC did not disengage the screw drive when the body was switched to MF, and in twisting the focus ring I must have messed up the gearing. The focus ring will turn a bit, then get very stiff, and with force will release for another maybe .5" of turn, then stick, stiff-free on and off all around. So I think it's busted and I've ordered the replacement (the DA-L) already.

Lessons learned: cheap non-standard gear should be used with great caution!

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