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04-12-2011, 03:26 PM   #1
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could someone please tell me what this is?

When I was cleaning my smc M135 f3.5 this fell out of the part of the lens that attaches to the body. No idea what it is for. anyone have any ideas what it is and if I need it?
It sits inside the mount of the lens (if that makes sense)
thanks



04-12-2011, 03:36 PM   #2
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Looks like a baffle to cut down on stray reflections.
04-12-2011, 03:38 PM   #3
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Yup, that's exactly what it is. A lot of lenses have these (that don't have elements near the mount)..

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04-12-2011, 03:43 PM   #4
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thanks guys. which angle does it go back in and does it cut some of the light so the lens won't be as fast?

thanks a million

cheers

04-12-2011, 03:52 PM   #5
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The baffle has only one orientation to ensure the lens performs correctly and it attaches with a few small screws. You can go without it but may get some minor reflections off parts in the mirror box
04-12-2011, 03:55 PM   #6
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QuoteOriginally posted by Lowell Goudge Quote
The baffle has only one orientation to ensure the lens performs correctly and it attaches with a few small screws. You can go without it but may get some minor reflections off parts in the mirror box
so buy mine coming off does that mean it is broken off?

thanks
04-12-2011, 05:49 PM   #7
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It shouldn't just fall off. I'm assuming that since it just fell off, that it's supposed to snap into the lens somehow. One thing you do need to give some attention to, is to make sure that it is aligned properly when you reinstall it. I'm thinking that the longer dimension should go across the top and the bottom of the lens to coincide with the orientation of the sensor. I have a Tamron 50-200 zoom that has that kind of baffle on the back of the lens. The orientation is as I previously described.

04-12-2011, 06:10 PM   #8
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On my 300/4 this looks like it is part of the assembly with the flange that protects the aperture lever. It attaches by 3 screws through the side of the mount
04-12-2011, 08:40 PM   #9
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I have at least six or seven photos of Pentax-M 135/3.5s that don't have a rectangular baffle. It looks like the K version to me, which looks like this:



The orange diamond above the aperture ring should end up at top center when the lens is mounted. The center of the long side of the rectangle should line up with the orange diamond. Don't worry that much about alignment. On APS-C, because the longest dimension of the sensor is the same as the shortest side of the film rectangle, you could be 90 degrees off and still OK.
04-12-2011, 09:55 PM   #10
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QuoteOriginally posted by Just1MoreDave Quote
I have at least six or seven photos of Pentax-M 135/3.5s that don't have a rectangular baffle. It looks like the K version to me, which looks like this:



The orange diamond above the aperture ring should end up at top center when the lens is mounted. The center of the long side of the rectangle should line up with the orange diamond. Don't worry that much about alignment. On APS-C, because the longest dimension of the sensor is the same as the shortest side of the film rectangle, you could be 90 degrees off and still OK.
I was curious about this too. I have an M135 f3.5 and a K135 f2.5. Just as Dave stated, my M has no baffle, but the K does. It appears, as wheatfield said, that it may have been been simply cemented in.
04-12-2011, 10:07 PM   #11
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To add to the plot, I have a K 200mm f4 which has an identical plate. It's cemented in (and is matte black).
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