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08-04-2009, 06:09 AM   #1
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Issue with Tokina 85-200

Hey guys

I've following this forum for a while now but never happened to post hehe

I recently bought a Tokina EL Auto 85-200mm for the PK-Mount, but it seems it won't work on my K10D. The lens actually fits but it can't detect the aperture.
I guess maybe an adapter would fix the problem but i'm unsure which one...

08-04-2009, 06:45 AM   #2
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Is it an A series lens? If it isn't, you need to read up on the green button kludge.
08-04-2009, 07:07 AM   #3
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Original Poster
I'm not sure actually... and i can't seem to find any info on it

Got some pictures tho

08-04-2009, 08:22 AM   #4
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In the words of Microsoft, it's not a bug, it's a feature.

Whenever you hear someone mention that Pentax DSLRs can use every k-mount lens "with some restrictions" this is what they mean. It doesn't make the lens non-function, rather, it just means there's no way of detecting the aperture with any of the K or M series lenses.

It will still shoot the lens at the correct aperture. You have to enable the "Use Aperture Ring With S Lens" (or something similarly worded) in the camera's menu. When taking photos, you have to stop down the metering with the green button, then take the shot.

Reasons for this: the original K-mount had two levers. If you look into, say, an original K-series camera through the lens mount, on your right is the lever that detects the aperture the lens is set to. If you look at the mount on the lens and change aperture, you'll see a corresponding lever moving. That's how the original K-mount communicated aperture info with the camera body, letting you shoot in Av mode and meter wide open.

The second matching levers on the lenses and the bodies held the lens open, and when the shutter was pressed, released, stopping the lens down to the selected aperture.

Anyway, on the digital bodies and the *ist film cameras, the first lever was removed to save space. Pentax figured most people would be using the modern AF lenses, which communicate aperture info via those electronic contacts on the lens mount. Or maybe they just wanted people to buy modern lenses to replace their old ones.

Some these older lenses have no way of communicating apertur info to the cameras with this mount (called the "Crippled" KAF mount) and thus have to have the lens stopped down to metering, before you can shoot.

I've made it sound more complicated than it is.

But it's a helluva lot better than Nikon's solution to using old lenses.

08-04-2009, 09:06 AM   #5
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I didn't know that, thanks a lot!!
That was EXTREMELY helpful, it works perfectly now ^^

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