RB67 MLU - this doesn't seem right...

[M Carter]

Owned my RB for maybe 20 years but just had a situation where MLU seemed like a good idea. I tried it with the film back off so I could verify I'm doing it right, 90mm lens.

Lens set to F8 and 1/15th. Set the switch to "M", attached a cable release; cocked the camera and fired it via the body shutter release, no cable on the body.

Looking through the back, the curtain lifted and the shutter was open at F8 (well, not wide open anyway). Firing the cable release made the shutter close. Tried it multiple times - every 5th time or so, firing the body would do what I expected - the curtain/mirror did their thing, but the shutter was closed. Pushing the cable release then actuated the shutter properly.

So I assume this isn't working correctly. I'll break out some other lenses and try them, but am I missing something? never used MLU before - mainly use packs and heads.

 

[Theo Sulphate]

Double-check with page 29 here:

http://www.google.com/url?q=http://...gglMAE&usg=AFQjCNEInXYh-qgIceh4Z3vT-8UmB9rj4A

 

[WilmarcoImaging]

Start with the body and lens in normal, not MLU, mode.
Cock and fire the body/lens as normal.
Cock the body and lens, again. Set the MLU switch to M.
Fire the body using a finger as normal on the silver release button, or a cable release in said button. This raises the mirror.
With a cable release in the lens, release the shutter.

This is how it should work, and does work, on my Pro-S and 2 Pro-SDs, with C-lenses and KL-lenses.

Also as Theo mentioned read and re-read the instruction manual.

p.s. Just tried the above steps with a Pro-SD and 50 C lens and it works.

 

[Neil Grant]

Lens set to F8 and 1/15th. Set the switch to "M", attached a cable release; cocked the camera and fired it via the body shutter release, no cable on the body.

So I assume this isn't working correctly. I'll break out some other lenses and try them, but am I missing something? never used MLU before - mainly use packs and heads.[/QUOTE]

..you can test the lenses for correct 'mu' operation off-body if you want: depress the small silver button on rear of mount, then turn the firing pins all the way. The shutter should close but NOT fire, until either the calble release into the lens size is activated or the lens lens is turned 'off mirror up'. Don't know why these should fail. Does the shutter trip intermittently in normal operation?

 

[Trail Images]

OP, if you're referring to Mirror Lock Up usage and it is intermittent it is usually a lens issue that needs a CLA. I only shoot with MLU in use.
To verify what is happening it is always a good idea to isolate the lens and body and work them separately to see what is taking place. Some lenses are marked "Mirror Up" & "N" or red dot. Others just "M" & "N" or red dot. This MLU button or switch requires being pulled out ever so slightly when turning it in either direction.
The process Neil mentions on testing the lens off camera should provide an idea as to what might be taking place with regards to the lens operation.
I usually take the lens and place the MLU button to "Mirror Up" mode. Then cock the lens rotating the cocking levers to the open position. Looking at the back of the lens turn CCW. Should have some red & green dots there. I then press the small silver button to release the shutter cocking levers and turn them CW. The aperture should close as the MLU is still engaged. Then just rotate the MLU to N or the red dot and you should see the lens operate to open the set f-stop and the set shutter timed speed.
In the past I've seen lenses operate 4 out of 5 times or be sluggish testing off camera. Those get sent in for CLA and problem is resolved. I always mention in the CLA instructions to the repair group the complete usage of MLU to be sure that is tested that way too.

 

[M Carter]

Thanks guys - I played with it for a while on a camera stand with the back removed - had one more incident of the shutter opening with the body fire, and then closing with the lens fire, then it worked normally for a good dozen actuations. Then tried a 65 and a 250 which all worked. The 90 is my least-used lens, it hasn't been fired in years - maybe it just needed to be exercised a few times, it's worked fine in the normal mode this week.

I'll keep an eye on it though - I shot a roll once with a 180 with a frozen shutter and it gave me no clue it was sticking, so I tend to pull the back and check the operation now when I'm setting up. In fact, one of these days I want to get a couple rolls of cheap B&W and test all my lenses for shutter timing, maybe just shoot a gray card with every lens at 3 different speeds and check the density - I have a feeling my 250 may be a little slow.

 

[Trail Images]

OP, very good to hear. I've had similar issues. Certain lenses that see less usage I exercise a lot before putting them into service. These old RB's like to be used and they seem to have more issues with sitting then over activity. At least from my POV as I use the heck out of my stuff........