Leica R4-R7 air piston cleaning?

[shawn]

Has anyone tackled a shutter lag on a Leica R4-R7? Basically the camera works fine but there is variable lag between stopping down and the mirror actually starting to move. You see the lens completely stop down through the viewfinder before the mirror starts to black out. Sometimes it is fairly quick, sometimes it is considerably longer. This occurs in both electronic modes as well as in the battery less mechanical shutter speeds. I have read that is is the mirror air piston damper needing to be cleaned. Found where it is and how to clean it in a Minolta XD service manual (pretty easy) but it looks like getting at it on a R4 is a little more complex. Anyone done this and tips to get the DOF lever off and the plastic around the lens mount removed?

Shot right side up sometimes it fires almost fine, sometimes the delay is longer. Per the Minolta manual it is only supposed to be 56ms between the aperture actuator starting to move and the mirror moving. The variation be seen in this video. That was shot on the mechanical 1/100 setting. A few times it has been close to 1/2 between the two actions.

The delay gets *really* obvious when you turn the camera upside down and fire it.

[video]https://www.flickr.com/gp/39387871@N06/6w531W[/video]

Thanks,

Shawn

 

[CameraQuest]

The Leica 35mm SLRs (all flavors) are among the most difficult SLRs to work on.

As a result many pro techs will not service them.

My advice is to not risk your camera, send it to DAG.

 

[shawn]

The piston is basically right behind the dof lever. On a Minolta you take the plastic trim off around the lens mount and you are there. That is why I wanted to see if anyone had done this on a R4. DAG has one of my lenses right now but I bought the R4 for $135 and can return it if needed. Probably not worth sending it to DAG in this case. He likely will be getting my SL2 for an overhaul though.

Thanks,

Shawn

 

[Bill Blackwell]

... My advice is to not risk your camera, send it to DAG.

DAG is among those who won't service R cameras. He'll only service Leicaflex SL/SL2 SLR cameras.

 

[shawn]

DAG is among those who won't service R cameras. He'll only service Leicaflex SL/SL2 SLR cameras.

I had read that elsewhere but hadn’t confirmed it. I emailed Zack’s but have not heard back from them, I know they don’t work on the SL2 though.

Shawn

 

[Beemermark]

Do you use mirror lock up that often? Big heavy camera with big heavy mirrors like the Nikon F series needed it but I never use it on my F100 or F5. And when your using the mirror locked up it's a rather slow process anyway, does it matter how long the delay is? Might just need exercised.

 

[shawn]

The R4 does not have mirror lock up. This delay is in normal shooting.

Shawn

 

[Bill Blackwell]

The R4 does not have mirror lock up. This delay is in normal shooting. ...

I believe what you're experiencing is the deterioration of the foam around the inside of the back door (there is also a small piece above the mirror box). It gets sticky as it deteriorates and sticks to the mirror as it snaps up. The foam needs to be removed and replaced. If this is a recent purchase, I'd say return it for a refund.

 

[shawn]

I believe what you're experiencing is the deterioration of the foam around the inside of the back door (there is also a small piece above the mirror box). It gets sticky as it deteriorates and sticks to the mirror as it snaps up. The foam needs to be removed and replaced. If this is a recent purchase, I'd say return it for a refund.

Maybe but I don't think so, the mirror isn't sticking up at all in its motion and the foam doesn't look bad. There is no residue of foam on the mirror. I could certainly swap out the foam but if it were foam I do not see how it would cause this issue, esp. with position changing the delay so much.

This problem is the opposite of sticky mirror damping foam which tends to hold the mirror up. The activation of the mirror movement (and shutter firing) is delayed. I've found a number of posts in regards to this.

Page 45 of the XD11 manual regarding mirror cage repairs. (R4 uses basically the same shutter system)

https://learncamerarepair.com/downlo...pair-guide.pdf


"Earlier, we mentioned that the air piston on the side of the mirror cage provides the memory time lag. The air piston actually releases the mirror. When the mirror-release magnet disengages the mirror-release lever. Fig. 106, the springdriven piston moves down. The piston then disengages the mirror-lifting lever.....problems — even a failure of the mirror to release. You can remove the air cylinder for cleaning without taking out the mirror cage. Just remove the two screws holding the air cylinder; reach the screws through the cutout at the side of the lens mount, Fig. 107. But be careful — both the air piston and the compression spring inside the cylinder will be loose. After you clean the parts, wipe the inside of the air cylinder with a thin coat of shutter oil."



and then this explanation of the problem:

"I am happy to advise you that the camera does get faster if repaired properly. If the delay in the camera is enough for you to notice it is probably not the final check metering system. It is likely due to a soiled mirror damper. Here's a cut from another post on the MIR site.

"In the XD11 (XD7) a pneumatic damper delays the mirror and subsequent shutter firing for about 52 milliseconds after the aperture has started to close down. This is in order to make sure the aperture has closed down and has stabilised. When the damper reaches the end of its stroke, the light value metered through the closed aperture is stored in memory and determines the shutter speed, upon which the mirror lifts. When the mirror has lifted about two thirds of the way up, the shutter fires.

A soiled mirror damper will slow the pneumatic piston down and the delay between the aperture closing and mirror lifting may then be several seconds in severe cases. When fitted in the factory the damper piston is lubricated and then wiped dry before inserting in the cylinder. The minute remaining oil film can become a bit sticky after many years. The damper will have to be removed, cleaned, lubed, cleaned again an refitted. After that the damper timing has to be re-adjusted by adjusting a tiny screw on the damper which sets the length of the damper-stroke.

A worn damper leads to too short a delay and will give inconsistent underexposure of the film as the light value is stored in memory before the aperture has completely closed down. Usually this means the damper has to be replaced with a new one.

The mirror damper can be accessed and removed after removing the plastic cover around the lens mount and the little cloth-tape covered damper cover underneath. Get an expert repairman to clean it for you. If you want to do it yourself, you can use lighter fluid to clean both the piston and cilinder. Lube only the piston with a VERY thin and light oil and wipe dry before refitting. Beware which way the spring comes out of the damper when you remove it, the spring has a short and long tab at either end."

Cheers!

Antony"

Another explanation of how to fix an XD

"Hi Justin,
The problem you describe is quite common with XD cameras. It's caused by dust that collects in the air piston. This air piston is responsible for delaying the mirror release for the "final check" metering feature. Excess dust will clog the piston and make it move slower.

I think I've posted this before, anyway, here's the short version:
-Take off the bottom cover
-Unscrew the 2 screws between the lens mount and the nameplate.
-Take off the bayonet mount
-Take off the plastic lens mount cover
-Peel off the plate on the side of the lens mount, close to the self timer
-Unscrew the air piston holder
-Clean the piston with lighter fluid and lint free lens paper. Poke dirt out of the air hole with a needle.

You may not have to take off the bayonet mount. It depends if you have enough wiggle room around the leatherette to take off the plastic cover. Assembling the bayonet mount can be somewhat fiddly due to the long spring that attaches to the aperture coupling ring."


I've read that it is dust or the lubricant used in the air piston gets sticky over time which causes the lag.

EDIT: The magnet release can also get sticky over time and have basically the same lag but I don't think that is used on the mechanic shutter speeds.

Thanks,

Shawn

 

[shawn]

Mike Ekman details this exact problem and repair on his site. Getting at it in the R4 looks different though due to the DOF preview lever and maybe needing to lift the top cover as the Leica doesn't have that small panel that can be remove above the lens. This issue potentially can be on any R4-R7. The R3 used a different XE based chassis.

Shawn

 

[shawn]

For future reference... to get at the air piston to disassemble it involves removing the mirror box on the R4-R7. A much bigger job than on the Minoltas. However, there is an access tab inside the mirror box that lets you get to it to put a drop of oil on it. Basically a small thin brass tab that covers a hole in the side of the mirror box. Details here.

The delay had gotten worse as I was exercising the camera to the point that it had gotten to a several second delay. One drop of oil and it is running great now.



Shawn