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Old Jun 20, 2007, 3:26 PM   #1
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So I seem to be really spoiled by the new found focus trap feature.

The new screw mount lens seems to sometimes work with the focus trap feature.

So far the only fix that I have come accross is to put some aluminum foil between the lens and the contacts on the body. Does anyone else have any ideas they would like to share?

Does the pin serve any purpose or could it be removed?

Thanks

Fred
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Old Jun 20, 2007, 3:31 PM   #2
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Sorry about all the posts seem to be having some problems here again.
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Old Jun 20, 2007, 6:04 PM   #3
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I was never able to get a clear understanding of what is required to get focus trap to work properly with my *ist DS and screw mount lenses.



As far as I could determine putting foil etc on the pins fooled the camera into 'thinking' the lens was more capable that it is. The result was erratic over-exposure (usually) which I assume was because the camera 'thought' it could stop the lens down.
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Old Jun 21, 2007, 1:28 AM   #4
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I would say it doesn't and having one full manual (135) lens... no that should make no difference..... its purely an optical not electrical thing. (Still a K but no contacts (not even blanks like an A with the one out of 4) flat metal K/M surface, pretty much the same as a M42 adapter)

Now a very fast shallow DOF in low light lens (like 1.4) may be be difficult for it to lock unless you shift VERY slowly... lens like that eye usually does better and maybe somethines get the AF confirmation if there are sharp contrasts.

I know my A 1.4 is like that only occasionally will I get AF confirmation in dim light without trying back and forth slowly several times when no real sharp contrast, just rely on eye... and thankfully the K10D pentaprism vs mirror makes that easier..
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Old Jun 21, 2007, 2:55 AM   #5
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One of the pins on the camera is different and does not pop above the level of the camera flange. Putting on a lens with a pin in that position would make contact but other lenses including withthe M42 adapter would not.
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Old Jun 21, 2007, 3:57 AM   #6
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Well I have to admit no isT* experience just K.... but A's only use the first contact (rightmost looking at the mount contacts bottom) K-M lenses are just plain smooth metal like an adapter.

Ever tried a K-M lens on that camera.... same problem?
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Old Jun 21, 2007, 9:31 AM   #7
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I have a couple full manual lenses. They all work fine auto focus assist (confirmation light). Which means they work perfect for the focus trap technique.

Only this new (to me) lenswhich isa screw mount has that extra pin that stick up off the lens.

Can this pin be removed ? I could not imagine it serves any purpose (since the lens is about 30 yrs old). Has anyone taken this pin off, maybe snipped it off?

Have some pictures for reference. Pictures show the lens with the K mount adapter installed.

Thanks

Fred




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Old Jun 21, 2007, 12:38 PM   #8
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Hi Fred,

There's no advantage to removing the pin, it was used by screw mount bodies to stop the lens down during exposure in auto diaphragm mode -- it doesn't do anything on a K mount body, but it also doesn't interfere with anything, so just ignore it.

Scott
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Old Jun 21, 2007, 3:55 PM   #9
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snostorm wrote:
Quote:
Hi Fred,

There's no advantage to removing the pin, it was used by screw mount bodies to stop the lens down during exposure in auto diaphragm mode -- it doesn't do anything on a K mount body, but it also doesn't interfere with anything, so just ignore it.

Scott
Scott, so I m just wondering why the focus trap technique is not working with this lens? It work with all my old k mount lenses. They look very similar except that pin.

Thanks

Fred
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Old Jun 21, 2007, 8:22 PM   #10
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Hi Fred,

I don't have any M42 lenses with adapters handy, but I'm thinking that they either have a very shallow channel or bevel (since they don't cover the entire width of the K mount) machined into the camera side of the adapter that allows it to clear the contacts on the body, or that they have a coating like a clear lacquer that insulates the metal of the adapter from contacting the contact pins. If it's the second case, it wouldn't take much to insulate the adapter since there is only a very small amount of current that passes through them.

Now where could I have put those. . .:shock:

Scott

Sorry, now that I think about it, the adapter can't contact the pins, and the body of the lens probably don't contact them either, or the paint on the back surface of the lens insulates it from making contact. -- Duhhh!

If your lens makes contact with the pins, it's probably just a matter of removing the adapter, carefully scraping off the paint in the area where the lens would meet the contacts, then carefully cleaning the scrapings from the flange and the threads of the mount before trying to remount the lens. Other than that, the aluminum foil is really cheap and works.

Scott
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