could someone please tell me what this is?

slip · 04-12-2011, 03:26 PM

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

borno · 04-12-2011, 03:36 PM

Looks like a baffle to cut down on stray reflections.

Adam · 04-12-2011, 03:38 PM

Yup, that's exactly what it is. A lot of lenses have these (that don't have elements near the mount)..

slip · 04-12-2011, 03:43 PM

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

**Lowell Goudge** · 04-12-2011, 03:52 PM

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

slip · 04-12-2011, 03:55 PM

Originally posted by Lowell Goudge

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

jimH · 04-12-2011, 05:49 PM

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.

**Lowell Goudge** · 04-12-2011, 06:10 PM

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

**Just1MoreDave** · 04-12-2011, 08:40 PM

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.

wasser · 04-12-2011, 09:55 PM

Originally posted by Just1MoreDave

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.

Wombat · 04-12-2011, 10:07 PM

To add to the plot, I have a K 200mm f4 which has an identical plate. It's cemented in (and is matte black).

04-12-2011, 03:26 PM	#1
slip Veteran Member Join Date: Oct 2006 Location: 2 hours north of toronto ontario canada Photos: Gallery \| Albums Posts: 3,535	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, 03:38 PM	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Yup, that's exactly what it is. A lot of lenses have these (that don't have elements near the mount).. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

04-12-2011, 03:36 PM	#2
borno Veteran Member Join Date: Nov 2006 Location: md-usa Photos: Gallery \| Albums Posts: 2,580	Looks like a baffle to cut down on stray reflections.

04-12-2011, 03:43 PM	#4
slip Veteran Member Join Date: Oct 2006 Location: 2 hours north of toronto ontario canada Photos: Gallery \| Albums Posts: 3,535 Original Poster	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
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	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
slip Veteran Member Join Date: Oct 2006 Location: 2 hours north of toronto ontario canada Photos: Gallery \| Albums Posts: 3,535 Original Poster	Originally posted by Lowell Goudge 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
jimH Veteran Member Join Date: Apr 2009 Location: South Central Nebraska - USA Photos: Gallery \| Albums Posts: 1,771	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
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	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
Just1MoreDave Site Supporter Join Date: Feb 2007 Location: Aurora, CO Photos: Gallery \| Albums Posts: 6,340	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
wasser Veteran Member Join Date: Jan 2009 Location: northern ca Photos: Gallery Posts: 427	Originally posted by Just1MoreDave 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
Wombat Veteran Member Join Date: May 2008 Location: South Australia Photos: Gallery \| Albums Posts: 901	To add to the plot, I have a K 200mm f4 which has an identical plate. It's cemented in (and is matte black).