RB67 Mirror Lockup Problem

Hello there,

I recently purchased an RB67 Pro-SD with a KL 90mm f/3.5L lens. I am having problems getting the mirror lockup function to work.

The KL 90mm has no knob for mirror lockup, just the socket for inserting the cable release. As I understand it, the procedure is to screw a cable release into the socket, which should cause it to elevate so that you can see the red line appear. Then you can depress the camera's shutter button to fire the mirror, and use the cable release to fire the lens shutter.

So far so good.

The problem is that when I screw a cable release (I have tried about 5 different cable releases) into the socket, it does not cause the socket to elevate sufficiently to put the lens in mirror lockup mode. If I screw a cable release in and then pull on it I can bring the socket out far enough to see the red line and this successfully engages mirror lockup as long as I keep the socket pulled out, but of course this is useless.

So I am wondering if there is a special cable release for the RB67 which causes the socket to elevate more than normal? Or if not has anyone else experienced this problem and resolved it somehow?

Thanks in advance!

A normal cable release should be fine. They can vary a bit but you shouldn't need to try 5 to get one that works.
Don't be timid - screw the release in with a bit of finger force if its not going all the way in. If it really won't go in enough, could be that the threads of the socket are damaged.

That's odd. I have 2 standard ones that cost me 2 bucks that both operate the 'lift' perfectly.
Maybe, as stated, yours is damaged.

I screw mine in and once it has bottomed, the whole assembly turns until the red line is showing, like it is on some kind of cam.

well that is what I was afraid of - I guess there is something wrong with it then. anyone ever taken the mirror lockup socket apart?

nwilkins said:

well that is what I was afraid of - I guess there is something wrong with it then. anyone ever taken the mirror lockup socket apart?

Click to expand...

Before taking it apart have you tried cleaning it? It may be that there is dirt in the thread or the socket stopping you from screwing in the cable release completely.

yes, the socket is clean - it even starts to elevate a bit once the cable release is threaded in, but it does not elevate enough to engage mirror lockup. Looking at it again, the metal bracket which holds the socket is a little loose, so I wonder if screwing that more tightly to the body will cause the socket to elevate further? I will keep my fingers crossed as I search for a tiny screwdriver.

alas that was not the problem. I am now wondering if the socket is actually elevating far enough (the red line is barely visible, but visible nonetheless). In that case the problem is with the activation lever inside the lens, needing to be pulled even further than normal.

I guess I will try shooting on a tripod without MLU and see how bad the vibration actually is.

I have a generic cable release that operates my 127mm mirror lock-up mode perfectly. I would try some other brands of release cables before you start taking anything apart -- just a suggestion. Also, what condition is the lens in?

yeah as I said I have tried about 5 or 6 different cable releases so it is definitely not that. The lens seems to be in good optical condition, though there is a little scuffing and slight deformity in one small section of the filter threads. This probably indicates someone went into the lens at some point and didn't quite know what they were doing, so that might have something to do with the MLU problem?