Mamiya RZ67 Pro with RB K/L lenses for long exposures

I want to use the RB 65/4 K/L lens with my Mamiya RZ67 Pro camera for long time exposures. I have the electronic cable release which works perfectly fine with Z lenses and also with this RB lens as long as exposures are 1 second or less. It is getting tricky when trying to do a longer exposure with this lens (exposure setting needs to be done on the lens directly). The mirror and the shutter open in the T position but the lens shutter doesn't close when the electronic cable release is pressed again. I figured that I likely need to use an additional cable release attached to the B position of the RB lens - when pressing this second release, the shutter closes but it does not work to open it. Is this the correct way to do long exposures with this camera/lens combination? Pretty much releasing the shutter with the "regular" electric cable release attached to the RZ67 Pro and then closing the shutter with the secondary cable release attached to the B position of the lens?

The 65mm KL shown here https://rb67.helluin.org/wp-content/uploads/2010/08/KL-65mm-f4.jpg has the normal shutter range 1/400 to 1 sec. In the T setting the shutter opens in response to operation of the release. The shutter closes in response to a slight motion of the cocking lever.

On the side of the lens is the optional shutter release for mirror-up operation. The regular shutter release button on the camera body trips the mirror but not the shutter. A separate cable release fitted to the lens-side location is used to fire the shutter.

So far as I know there is no B setting on RB lenses.

Thanks for the reply - you linked the correct lens, and you see in the photo both cable release inserts. One is for the mirror lockup, the other is the B position to close the shutter (you can actually see the printed B in the linked photo on the right next to the X inlet hole). Could you please explain your sentence "The shutter closes in response to a slight motion of the cocking lever"? I think I know what you mean - after I released the shutter with the electronic cable release attached to the RZ67 Pro body, the shutter also closed when I simply turned the frame/film winder. But this can't be the right way to do it since the exposure time is very unclear by doing this and you might create some motion blur by doing so. So I thought before turning the winder to lower the mirror, I better press the manual cable release attached to the B inlet button to close the shutter and then turn the winder to advance to the next frame. I am not sure if I need at all the cable release to lock the mirror upfront - my electronic cable release does it automatically before opening the shutter (it might only help to avoid vibrations which I am not too concerned about at this point). There might be several ways to do it, but the combination between RX67 Pro and older RB lenses (which are backwards compatible to this camera body) are not well documented online when it comes to long exposures.

Thank you for pointing out the "B" release on the KL lens. This is new to me, it is not present on my RB lenses. This limits the usefulness of my remarks.

Regarding the use of the cocking lever to close the shutter, yes, I agree, this seems a little unsophisticated, however it is how all the RB lenses (those without the B socket) operate for long exposures. One has to be careful to avoid vibration, and yes, timing may vary slightly between exposures made by this method.

Not sure I can contribute much else......

I think I figured it out - the "old" way uses two manual cable releases one attached to the mirror up inlet (M.UP) and the other one attached to the B inlet. The exposure ring needs to be in T position. First the shutter is released by pressing the shutter release button which flips only the mirror. By pressing the cable release in the M.UP inlet, the lens shutter opens. The shutter can be closed by pressing the second cable release attached to the B inlet. Then the winder can be turned which brings the mirror down and makes the camera ready for the second frame. The difference to the first method which I lined out above with the electromagnetic cable release is that by pressing it both the mirror flips up AND the shutter opens instantly. Closing the shutter works in the same way by pressing the manual cable release attached to the B inlet. For very accurate long exposures the old way with two manual cable releases seems a bit better since it allows me to open the lens shutter at an exact time after the mirror is already in its up position.

It seems there is a choice of methods, choices are good

Long ago when I had just purchased my RB67 and was "accessorizing" I bought the special Mamiya twin cable release thinking it to be essential for the MU operation. Later it dawned on me that things also work with a pair of simple mechanical releases. I still have the special twin release but rarely use it.

tedr1 said:

It seems there is a choice of methods, choices are good

Long ago when I had just purchased my RB67 and was "accessorizing" I bought the special Mamiya twin cable release thinking it to be essential for the MU operation. Later it dawned on me that things also work with a pair of simple mechanical releases. I still have the special twin release but rarely use it.

Click to expand...

Yes, this works both with twin cable release or with two separate cable releases as you stated. Likely not many are still making use of this long exposure feature with RB67 lenses.

A few days ago I tested my setup with Mamiya RZ67 Pro and attached Mamiya 65/4 K/L lens for long exposures. The photo below was taken at f/32 and 30 seconds. I used the following procedure to make it work in this camera-lens combo:
1. Turn OFF electric winder - it will not understand just to flip the mirror and will move to the next frame instead after the shutter release button is pressed with the electric winder in on position!
2. Move the lens exposure ring into T position.
3. Add two cable releases: one goes into the M.UP (mirror up) insert on the left of the attached lens, the second cable release is inserted into the B inlet on the right side of the lens.
4. Press the shutter release button - after the cable release was inserted into the M.UP inlet as described in (2), the shutter release will only open the mirror (you will hear a clank)
5. Press the cable release button of the one which is in M.UP position - it will now open the lens shutter. Count the seconds needed for the exposure (in my case 30 seconds)
6. Press the cable release button of the cable inserted into the B position - it will close the lens shutter. The photo is taken!
7. Manually move the cocking lever - it will bring the mirror down and move the film to the next frame. Ready for the next exposure.

It is not too complicate if doing it a few times!

Photo below is taken on Fuji Velvia 100F slide film, home developed with E-6, 30 seconds exposure at f/32.

Addition to my earlier post: very important to check on the RB lens after finishing long exposure shots that the little red ring of the M.UP insert is no longer visible after the cable release was removed. I didn't pay attention to this detail, and used the lens today for regular photos. To my surprise all frames came out blank which were taken with this lens today - I found that the lens shutter didn't open. I had to re-attach the cable release into the M.UP protruded insert with red ring visible and unscrew it directly afterwards - then the protruding insert button with the red ring disappeared into the lens body as it is supposed to do it after releasing the cable (and the red ring was no longer visible). Now the lens shutter works normal again - glad I didn't take too critical shots today, nevertheless I lost 7 out of 10. The three keepers were taken with the 110/2.8 Z-lens which fortunately didn't suffer a similar issue. Definitely won't forget this detail again!