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11-30-2011, 02:59 PM   #1
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Sigma 28mm for Pentax K doesn't fit

Hi guys, I need help I got this on ebay eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices and the thing won't fit my k-r. I was under the impression that pentax didn't/haven't change it's lens mount since like in forever. Do I need to do something special here? or is this a total newbie fail on my part.

11-30-2011, 03:14 PM   #2
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It "looks like" it should but I know there are some Sigma or other non-Pentax older lenses to that do not follow the K-mount spec exactly and can get stuck on or break a newer body if forced.
11-30-2011, 03:15 PM   #3
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I've updated your thread title to something a bit more relevant

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11-30-2011, 03:29 PM   #4
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I don't have that particular lens, but I do have a third-party K-mount lens that wouldn't fit at first, so I have a suggestion.

Sticking out from the back of the lens is a flange that protects the aperture lever. It looks like a rigid shark-fin protruding from the back of the lens next to the moving lever. On some lenses, that's either too wide or too long, and it interferes with the SDM/power zoom contacts inside the camera body (which didn't exist yet when these lenses were made).

Some people actually cut these off, or shorten them, with a saw. On my lens, I was able to undo a few small screws and remove only that protruding flange. That leaves the lever unprotected against impact, but I didn't mind. Keep a rear lens cap in place, and there's no problem.

If this were my lens, I'd try to gently loosen the screws that appear to hold on that black ring with the flange on it. Not all the way, but enough to determine whether the screws also hold anything else in place. If they don't -- and all they hold is the flange -- remove it. Put it away somewhere in case you want to resell the lens.

That's my suggestion. But again, I don't have this particular lens, so try it at your own risk!

11-30-2011, 03:33 PM   #5
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I have the same lens but it does not have the aperture flange.
11-30-2011, 03:41 PM   #6
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Thanks guys.

Quicksand, I think that's exactly why it's not fitting correctly, the shark fin thingy-majig is getting in the way. so you're saying that I can just cut it off? or cut a portion of it and it won't cause any complications with the lens operation? I inspected it again and tried to figure if I can take the thing out, but it looks like it is a part of the black ring. To be honest I kinda just want to snap it off there.
11-30-2011, 03:43 PM   #7
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boriscleto where did you get your lens? are there signs that the thing was hacked off there? Thanks
11-30-2011, 04:00 PM   #8
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Yeah, I think the flange and ring go together as one piece. But if you're lucky, those are the ONLY two things coupled together, so you might be able to take off the flange-plus-ring combination, and just forget they exist. The only function for the flange is to protect the lever against impact, and (in most cases) the only function for the ring is to attach the flange to the back of the lens.

Sorry if I was unclear about that. On my lens, I took off the whole ring, but nothing else was coupled to or dependent on that ring.

11-30-2011, 04:34 PM   #9
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Thanks quicksand, I was able to remove the screw but can't pull the black ring out. after taking out the screws the black ring swivels now making it possible for me to fit the lens. but when I tried shooting it, it's just saying F-- on the aperture screen, and nothing's coming out on the expose settings.
11-30-2011, 05:20 PM   #10
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QuoteOriginally posted by kaiserz Quote
it's just saying F-- on the aperture screen
No electrical contacts on that lens so you need to set "Use aperture ring to 'yes' " in the menu. See this sticky, using manual lenses, for more information. You will be asked to input the focal length when you turn the camera on and you will need to set the aperture on the aperture ring. Then use the green button for stop down metering.
11-30-2011, 06:35 PM   #11
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Thank you guys! (: I got it to work now.
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