Mayima RB67: can I remove lens even though I have film and lens is cocked?

[peterB1966]

Just got my cable to connect my lens to a hotshoe, but would prefer to check that it triggers the flash without wasting film.

 

[Don_ih]

Put the dark slide in and remove the film back. Fire the lens to check everything.

 

[Donald Qualls]

Put the dark slide in and remove the film back. Fire the lens to check everything.

It's also possible to fire the lens shutter with the lens off the camera (and you should do so if you'll be storing the lens for a prolonged period, to protect the shutter's springs -- and then make sure both lens and body are cocked before mounting the lens), but this is MUCH simpler for something like testing the flash. You can also look through the rear of the open body to verify that the flash is synchronizing correctly (not usually a big problem with X sync on a leaf shutter, but it's so easy to check, why not?).

 

[Alan Edward Klein]

You can slightly pull out the dark slide to release the safety interlocks so the camera will shoot without exposing the film.

 

[Donald Qualls]

You can slightly pull out the dark slide to release the safety interlocks so the camera will shoot without exposing the film.

But why? Just dismount the film back, and the body will work normally. You can also look inside to verify the mirror and safety shutter are firing correctly, and that the shutter is both closing, firing, and reclosing as it should.

 

[peterB1966]

Thanks for the replies!

...and then make sure both lens and body are cocked before mounting the lens...

Is there a reason for this? Would it not work if both are not coked first before reattaching?

 

[Alan Edward Klein]

But why? Just dismount the film back, and the body will work normally. You can also look inside to verify the mirror and safety shutter are firing correctly, and that the shutter is both closing, firing, and reclosing as it should.

He just wanted to check the flash. I assume the rest of the camera works correctly. Also, people may not know of this procedure to fake out the safeties. So now they know a number of ways to do stuff.

 

[Alan Edward Klein]

Thanks for the replies!


Is there a reason for this? Would it not work if both are not coked first before reattaching?

Peter, See pgs 10, 11 and 12 for shutter operation and removing and reattaching lenses.
https://www.cameramanuals.org/mamiya_pdf/mamiya_rb67_professional.pdf

 

[Donald Qualls]

Would it not work if both are not coked first before reattaching?

Short version: if you mount the lens with both body and lens uncocked, it won't mount, if their cocking state doesn't match, it will either not mount or potentially jam things up.

The cocking mechanism uses a pair of pins to pass the cocking torque to the shutter in the lens; if those don't match up with the actuators in the body, bad things can happen (including potentially being unable to dismount the lens again).

Simple rule: always cock before mounting or dismounting, release for long term storage.

 

[peterB1966]

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Much appreciated to both of you. Hopefully all goes well

 

[peterB1966]

It worked! Super amped

 

[Donald Qualls]

It worked! Super amped

Glad to hear it. Leaf shutters have pretty simple, generally robust sync contacts -- typically just two spring leaves with a contact point (often gold plated). Older ones can even handle the 400+ V from a direct triggered electronic flash.

 

[Neil Grant]

Short version: if you mount the lens with both body and lens uncocked, it won't mount, if their cocking state doesn't match, it will either not mount or potentially jam things up.

The cocking mechanism uses a pair of pins to pass the cocking torque to the shutter in the lens; if those don't match up with the actuators in the body, bad things can happen (including potentially being unable to dismount the lens again).

...fortunately the RB 67 cannot jam up as DQ suggests. If the cocking state of the body and lens don't match, they can be made to do so by either:
1) firing the camera
or
2) cocking the camera.
The lens's cocking pins are spring loaded, so if they don't match up with slots in the actuating ring then they just 'sit' ontop of it. When the body is fired or cocked the lens cocking pins will automatically engage as the springs push them forwards into their corresponding slots in the actuation ring. The RB is reassuringly error proof. Ideally, a lens should be mounted 'cocked' onto a 'cocked' body, but it really doesn't matter. It can always be sorted out later.

 

[Donald Qualls]

...fortunately the RB 67 cannot jam up as DQ suggests. If the cocking state of the body and lens don't match, they can be made to do so by either:
1) firing the camera
or
2) cocking the camera.
The lens's cocking pins are spring loaded, so if they don't match up with slots in the actuating ring then they just 'sit' ontop of it. When the body is fired or cocked the lens cocking pins will automatically engage as the springs push them forwards into their corresponding slots in the actuation ring. The RB is reassuringly error proof. Ideally, a lens should be mounted 'cocked' onto a 'cocked' body, but it really doesn't matter. It can always be sorted out later.

Well, I'm glad to be wrong, in this case. I've done this once, by accident, and thought I was just lucky that (IIRC) cocking the body cleared it up. Certainly nothing like what can happen if you don't mount a pre-AI Nikon lens properly and force it...

 

[epatsellis]

Usually, that works.....however it’s been my experience that several times since I’ve been shooting RB’s (early 80s), that I’ve had a body or lens jam due to the mismatch. Then it’s the dreaded paper clip trick to get them apart.

 

[Alan Edward Klein]

Usually, that works.....however it’s been my experience that several times since I’ve been shooting RB’s (early 80s), that I’ve had a body or lens jam due to the mismatch. Then it’s the dreaded paper clip trick to get them apart.

What trick?

 

[Donald Qualls]

What trick?

I think he's referring to using a paper clip in the shutter's cable release socket to release the shutter while the body isn't cocked. If a lens is jammed due to mounting a cocked lens on an uncocked body, this will restore matching states and at least let you dismount the lens, cock both body and lens, and correctly mount the lens.

 

[Neil Grant]

...I'm not sure that's what meant about the paper clip trick. On the rare occasions that an RB lens gets stuck on a body another, an altogether different 'trick' comes into play. Within the RB mount on the body is a 'blocking device' that prevents lens removal unless the body is cocked. If this sticks in the wrong position then the knurled mounting ring cannot be turned to it's 12 o'clock 'release' position. The 'blocking tab' is concealed beneath the leatherette covering near the mounting index, but can be 'got at' by pealing back a portion of leatherette and then 'poking' the blocking-tab into the release position using a paper clip.

 

[Alan Edward Klein]

I think he's referring to using a paper clip in the shutter's cable release socket to release the shutter while the body isn't cocked. If a lens is jammed due to mounting a cocked lens on an uncocked body, this will restore matching states and at least let you dismount the lens, cock both body and lens, and correctly mount the lens.

If the lens is cocked, couldn't;t you release it by turning the knurled knob on the lens to Manual and then back to Normal?

 

[Donald Qualls]

If the lens is cocked, couldn't;t you release it by turning the knurled knob on the lens to Manual and then back to Normal?

Not sure. I haven't tried that, and I'm not near my RB stuff at the moment.

 

[epatsellis]

Sorry, damn life keeps getting in the way, LOL.
You can remove the leatherette where the pro-S logo is on the front and insert a paper clip to release the catch that keeps you from rotating the lock ring.

And, no, turning the lens from normal to mirror up mode ( note: not manual) will not release the shutter.