MX Mirror Return Bumper?

cloudsky · 08-12-2012, 11:34 AM

Hi everyone, I'm new here

I just bought a Pentax MX - my 2nd film camera and 1st film SLR.
I noticed the sound of the mirror returning to the down position, after tripping the shutter, is much louder than the sound of the mirror going up. Someone else's MX (

You Tube

) seems to have a quiter mirror return.

Below is a photo of my MX's mirror box. Am I missing some foam where indicated?

Thanks in advance for any help!

ofer4 · 08-12-2012, 12:23 PM

I'll be interested to see replies here, as the (digital) K-r has an unholy mirror return sound, as well. If some foam bumpers are available from other models, I'd consider an attempt to deaden the sound in mine, as well.

**TomB_tx** · 08-12-2012, 12:37 PM - **1 Like**

The original MX advertising proclaimed how the camera vibration took place after the shutter had fired and the mirror returned, because the MX has a pneumatic mirror damper the slows the mirror gradually as it reaches the top of the arc. They showed a oscilloscope trace of the vibration indicating that it was worse (and noisier) when the mirror came down. As a result it didn't need mirror-lockup, because the "clank" on return didn't affect the picture. This is an expensive way to build a mirror mechanism, that I first saw in the Leicaflex SL.
Curious that I never saw "pneumatic damper" mentioned in the LX literature, and it did have mirror-lockup - so I guess they went back to just a foam strip.
Anyway, the mirror MUST rest against a firm stop in the down position, as any slight change in the rest position will make the focus wrong. So it would not have had foam rests on the "down" stops. The LX did have a plastic pad (not foam) in the down stop, and it is the cause of bad focus and mirror sticking on an old LX.

cloudsky · 08-12-2012, 07:04 PM

Thanks, TomB_tx. I was afraid my mirror would break - I'm not sure if the paint on the return bumper actually wore off from repeatedly being hit by the mirror... You can see it in the photo.

Well this takes a big worry off my head. Can't wait to start shooting with this girl

Edit: Sorry TomB_tx, I meant to thank you for the eloquent and detailed description. It makes perfect sense. Forgot all about that as I was composing my reply... It feels great to receive such a useful reply so quickly! Fantastic!

Last edited by cloudsky; 08-12-2012 at 10:15 PM.

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08-12-2012, 12:23 PM	#2
ofer4 Veteran Member Join Date: Jun 2011 Location: Utah Posts: 428	I'll be interested to see replies here, as the (digital) K-r has an unholy mirror return sound, as well. If some foam bumpers are available from other models, I'd consider an attempt to deaden the sound in mine, as well.

08-12-2012, 12:37 PM - 1 Like	#3
TomB_tx Loyal Site Supporter Join Date: Jun 2011 Location: Texas Photos: Gallery Posts: 1,446	The original MX advertising proclaimed how the camera vibration took place after the shutter had fired and the mirror returned, because the MX has a pneumatic mirror damper the slows the mirror gradually as it reaches the top of the arc. They showed a oscilloscope trace of the vibration indicating that it was worse (and noisier) when the mirror came down. As a result it didn't need mirror-lockup, because the "clank" on return didn't affect the picture. This is an expensive way to build a mirror mechanism, that I first saw in the Leicaflex SL. Curious that I never saw "pneumatic damper" mentioned in the LX literature, and it did have mirror-lockup - so I guess they went back to just a foam strip. Anyway, the mirror MUST rest against a firm stop in the down position, as any slight change in the rest position will make the focus wrong. So it would not have had foam rests on the "down" stops. The LX did have a plastic pad (not foam) in the down stop, and it is the cause of bad focus and mirror sticking on an old LX.

08-12-2012, 07:04 PM	#4
cloudsky Inactive Account Join Date: Aug 2012 Posts: 2 Original Poster	Thanks, TomB_tx. I was afraid my mirror would break - I'm not sure if the paint on the return bumper actually wore off from repeatedly being hit by the mirror... You can see it in the photo. Well this takes a big worry off my head. Can't wait to start shooting with this girl Edit: Sorry TomB_tx, I meant to thank you for the eloquent and detailed description. It makes perfect sense. Forgot all about that as I was composing my reply... It feels great to receive such a useful reply so quickly! Fantastic! Last edited by cloudsky; 08-12-2012 at 10:15 PM.