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Old Apr 30, 2007, 6:02 PM   #1
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I am a relative newbie andrecently bought a Tamron SP500mm mirror lens for under $125 used to use on my Pentax K110 digital SLR. When I turn the camera on there's an "AV" message flashing and the shutter can't be activated. I can focus the lens, but that's it. Perhaps there is something wrong I am doing or just don't know enough about. Can anyone help?

I searched the Pentax forums but didn't see a topic for tamron 500mm lens. Thanks in advance.
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Old May 4, 2007, 6:12 PM   #2
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Think you posted in the wrong section so won't get a reply, I would put it inhttp://forums.steves-digicams.com/fo...orum.php?id=80or http://forums.steves-digicams.com/fo...orum.php?id=94
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Old May 4, 2007, 7:17 PM   #3
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Hi onley,

I don't see why this is in the wrong section . . .

I have a Tamron SP500 mirror and it works fine on my DS, so I would only assume that it would also work with your K110. The Av is flashing because the lens isn't transmitting any aperture information to the body. If you have a PK Adaptall mount, this is normal, If you have a P/KA adapter, then the problem is probably a faulty contact area on the mount. Actually, since the lens has a fixed aperture, it almost doesn't matter except for the use of programmed flash.

If you have a P/KA mount, when you look at the back surface of the mount (the side that will attach to the camera, you'll see the tip of a screw that's coming from the other side just to the left of the contact pins on the mount. This screw was assembled at the factory using a thread sealing compound. Some of this stuff is probably coating the end of the screw and the surrounding area. The camera needs to ground to the lens flange right at this point, so you need to provide a good contact. Just scrape the end of the screw, along with a small area around it with a pocket knife or something similar. You don't have to scrape a lot, just enough to bare the metal. wipe the area with a damp cloth to remove any scrapings, let it dry, then try mounting the lens again. It should now show Av "8", and will act like a normal "A" lens.

If you have the P/K mount, forget the above paragraph -- the lens is acting normal, and you have to meter with the green button just like any other lens that doesn't have an A setting on the aperture ring.

I think that the shutter not firing is because you have the Auto Focus switched on. With a manual focus lens, the body will only fire the shutter when the focus confirmation indicator is lit in the viewfinder when the body is in AF mode. Switch it to MF, and it'll fire, even if there's no focus indication. This not firing unless in focus is actually a feature -- you can set your camera up on a tripod, pre-focused on an area, and then trip the shutter button. When something passes through that area, and the camera sees something in focus, it will trip the shutter as soon as it sees something in focus. It's called "Focus Trap" and comes in handy in certain situations.

Hope this helped

Scott
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Old May 4, 2007, 7:30 PM   #4
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I believe your problem is you need to change one setting in the menu. Open the menu, and scroll over to the CUSTOM tab. Scroll down to "Using Aperture Ring." Set that to "Permitted." I believe you will then find your problem solved. To the best of my memory that is the setting I changed to enable non "KA" mount lenses to function on my camera.

Tim


PS: Congrats on the new camera and welcome to the forum.
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Old May 4, 2007, 9:03 PM   #5
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Hi Tim,

Oops, you're right, first thing I do when I get a new Pentax DSLR -- don't even think about it anymore. . .:shock:

Scott
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Old May 5, 2007, 1:07 AM   #6
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snostorm wrote:
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Hi onley,

I don't see why this is in the wrong section . . .
When I posted that reply it was because the thread was in the Pentax point and shoot section before being moved here :blah:, now it is in the right place which is one of the two suggestions I made for it LOL.
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Old May 5, 2007, 1:15 AM   #7
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onley images wrote:
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When I turn the camera on there's an "AV" message flashing and the shutter can't be activated. I can focus the lens, but that's it. Perhaps there is something wrong I am doing or just don't know enough about. Can anyone help?
That is because of the nature of the FIXED F/ of the lens (f/8 on most) and that is the ONLY way it can function (Aperture priority),

The camera is smart enough to realize that and only allow that mode of functionality no matter what mode you try to set it to.

M lenses will be treated much the same way as well.

And I'm not tryhing to call you a dummy or anything like that.... didn't realize it myself until I got a Manual TC, and my K10D behaved that way but quickly realized why.... that is the only way it CAN with no contol of aperture.... SO AV is the only mode... no matter how you try to set it to... (other than M or B) it can operate in, just adjusting shutter for measuered light.

Now rereading you post, maybe the 110D is a little dumber than the 10D and you must put it in AV to function (take a shot).... the 10D it will just be in AV no matter how you set it (Even green/auto) because it knowns that's all it CAN do.

Now with a M lens you can change aperture manually and remeter.... yetstill an only shutter thing as far as cam automation is concerned, but mirror's are fixed aperture.... so yes there is no choice involved.

And as mentioned above if AF (which guessing that lens is not either) IS TURNED ON , then yes shutter will only trip IF THE CAM THINKS IT IS FOCUSED and agrees with your MF (VF blip and you don't overshoot in its opinion). Learned that with "A" lenses. (AE but MF) which also defauts to center point AF lock only in that case (despite any setting).... and actually my DYNAMIC anywhere in frame focus area vs just center was the more important thing actually especially with a f/1.7 very shallow DOF.... so the blip confermation aq nice clue but really of no importance for actual shot focus.

A, M, or non F/FA/DA... then just get used to setting MF by HUMAN/manual default.
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