RB67 MLU Problem

[david_gainer]

Has anyone experienced a problem with their MLU knob on their RB 67? I just

bought a lens but the MLU does not function, i.e. the shutter fires with the

body even though the knob is turned to "M." Should I return it or can I

remedy this myself?

[jean-louis llech]

David,<br>

First, check that the multi-exposure lever of the roll-film holder is not engaged. (This could explain why the shutter fires).<p>

 

Which model do you use ? RB67, RB67 Pro S, RB67 pro SD ?<br>

When you write <i>"the knob is turned to "M"</i>, you mean the mirror lock-up knob on left of the lens ?<br>

Normally, depressing the shutter release button will only rise up the mirror, but the shutter remains closed.<br>

Do you use a cable release on the MLU knob ?<br>

[david_gainer]

Jean-Louis, I have tested the other lens I have for the system and it does not exhibit this problem. I do have a cable release and it was in the socket when I was testing the lens - the shutter fired anyway.

[marck mcgill]

Then it could be the cable release. Unscrew it, pull the knob and set on M, fire the shutter and see if the blades open.

[david_gainer]

It fires even without a cable release in the socket, but while being set on "M."

[paul ron]

You say the shutter is firing?... have you looked through while the back is off to confirm this?

 

The MLU is controlled inside by a lever with a hook on it that catches the shutter control ring about half way through it's travel so it is just enough to close the blades down but not far enough to fire it. That knob keeps the hook in the up position out of the way when in Normal mode.

 

Once the hook catches the shutter ring tab it is waiting for you to push that lever down (making the hook go up) to disengage the hook which lets the control ring finish it's round firing the shutter.

 

Maybe the lever got bent by an over zelous user or the hook is worn out? Most MLU problems are generally the other way around, not releasing or disengaging back to normal.

[david_gainer]

Yes, I was looking through through the body with the back removed. I think I will find a qualified professional. Thanks to everyone for the replies, especially about the inner-workings of the MLU feature on the rb.