RB67 with problems

[Alex Bishop-Thorpe]

I just picked up my package at the post office this afternoon, an RB67 I'd bought from a chap on APUG recently. I'm not naming and shaming, as I think the seller's an honest chap, but I'm looking to work out if there's an issue in what I'm doing, or an issue with the camera.

The camera
-Mamiya RB67 Pro
-Pro-S 120 back (by my understanding this is compatible)
-90/3.8 lens (seems fine, ding in the filter ring)
-Waist level finder
-Prism finder

The problem
After loading the film and advancing to the first frame, I remove the dark side and cock the shutter. I release the shutter, and the problem emerges - the mirror raises slowly, and the shutter closes but never opens. I cock the shutter again, the shutter opens up and the mirror returns to it's previous position. I can't advance to the next frame.

I've removed the back and repeated this procedure. The light baffle behind the mirror raises up after the mirror, but only seems to go half way. It's not set to mirror lock. The little pin on the back doesnt fire to tell the roll film back it can advance.

I remove the lens, cock the shutter, and the mirror goes up at the expected speed and the light baffle goes up completely. The pin on the back does fire.

The problem seems to be with the lens, but do you have any suggestions?

 

[Steve Smith]

Although this doesn't appear to be the problem, make sure you don't have the lens set to mirror lock up. On some lenses this is automatically set by inserting a cable release, on others you manually set it.

In correct operation when you press the shutter release, the shutter will close, the mirror and the baffle will rise, the shutter will fire then remain closed. The mirror does not return until you cock the shutter again.

If you don't have the manual, download it here: http://www.butkus.org/chinon/mamiya/mamiya_rb67_pro-s/mamiya_rb67_pro_s.htm



Steve.

 

[Alex Bishop-Thorpe]

I thought of the mirror lock up just after I made the post and had a look - but it doesnt seem to be set. I dont even have a cable release with me at my current place, and the switch doesnt seem to function without it, so I cant really fiddle with it to see if it helps.

 

[Steve Smith]

You have probably tried this but I have one other thought:

Have you taken the lens off? In theory you can only remove and replace the lens if both the body and the lens are in the cocked position. If the lens was somehow mounted not cocked it may cause problems.

The manual shows you how to cock the lens with it off the camera by moving a pin. I think it needs to be lined up with a green mark.

Cocking it manually and then re-mounting onto a cocked (mirror down) body may put everything back into synchronisation.


Steve.

 

[panastasia]

I thought of the mirror lock up just after I made the post and had a look - but it doesnt seem to be set. I dont even have a cable release with me at my current place, and the switch doesnt seem to function without it, so I cant really fiddle with it to see if it helps.

When the lens is removed cock the shutter manually by pushing the two pins (on the rear of the lens) clockwise, or ccw, (I'm not sure which way it goes) and you'll see the shutter open, then put the lens on the camera and try again. If the shutter is closed the finder is dark and it would appear as though the mirror is up. I know that the camera will not function when the lens is installed with a closed shutter.

 

[panastasia]

Steve was ahead of my post by a couple of minutes.

 

[Alex Bishop-Thorpe]

Yep, tried remounting the lens - I was almost sure that was it. The Mirror Lock N/M switch can be changed when you lift it, I've tried changing that and it didn't help (almost sure it was that too).
I'm operating pretty much stripped down, no focusing screen, finder or back, so I can see what's going on pretty well. I've tried everything with the back attached too. Apart from noticing it could use some new foam around the mirror, what I'm getting is:
-Mount uncocked lens to uncocked body
-Cock shutter (I've also tried cocked lens to cocked body)
-Fire shutter
-Mirror raises up a little way, baffle behind mirror doesn't move.
-Cocking lever cant be moved, shutter release can't be pushed
-I have to shake the camera a little and the mirror moves up enough that I can re-cock the shutter.

Since the mirror and baffle operate fine when the lens isnt attached, I'm assuming some mechanism of the lens has gone somewhat wrong.

 

[Steve Smith]

Since the mirror and baffle operate fine when the lens isnt attached, I'm assuming some mechanism of the lens has gone somewhat wrong.

You are probably correct.

As the shutter has to close before the mirror and baffle can rise, I assume the lens must 'tell' the body that it is ready. Probably by another pin or lever.

I'm not sure about this as I have not tried working the lens without it being attached to the body.

I think the only answer now is to find someone else with an RB67 and try another lens.

It would be worth seeing if it does the same thing in mirror up mode. I know you said you don't have a cable release there so it may have to wait until you have one.


Steve.

 

[David Grenet]

Try setting the lens to mirror lock-up mode and firing the shutter. Does the problem with the mirror/light baffle continue? The shutter won't fire but can be fired without a cable release by setting it back to 'N'.

Does the shutter cock/fire when the lens is not attached to the camera (using procedure outlined above)?

If all else fails maybe Erie will know - he seems to know these cameras inside and out!

 

[panastasia]

The only other thing I can think of is the lens is set on bulb, or 'T'.

 

[David Grenet]

Ok, so I just got a lens out of the cupboard to play with and can offer this:

To cock the lens separately, turn the pins towards the coloured dots.

To release it hold down the small pin at the top of the back of the lens and slowly turn the pins away from the coloured dots.

Here's what should happen:

1. The shutter should close (this bit seems to be ok)
   
2. The aperture should stop down.
   
3. At the very end of the groove, the shutter should fire.

I suspect that the pins on yours may get stuck part way.

Hope it helps,

David

 

[max_ebb]

It definitely sounds like the lens is the problem. Have you tried firing the lens shutter with the lens off the camera (the way David G. described above)? I'm betting that the pins turn very stiffly instead of freely like they should.

 

[epatsellis]

To follow up on what David said, see the RB lens info on my website: Dead Link Removed for the sequence and what does what.

If it fires off camera ok, and doesn't feel like it's binding anywhere (even the slightest bit), it's time to make a decsision, either another 90 from KEH for <$100, or spend a few $$ and get a CLA done on the lens and enjoy it for the next decade or so. The way that the MLU is selected is quite unusual, and if the shutter isn't being tripped, then you have to dig pretty deeply to get it fixed, probably might as well overhaul the shutter while you're that far in, most haven't been looked at for over 10 years, they're definately due. If you plan on shooting 6x7 for a while, I'd get it cleaned, either Paul Ebel or Paul Ron both do good work. (I only work on my own lenses and cameras, sorry)


erie


erie

 

[Alex Bishop-Thorpe]

Luckily my university has a few RB67 bodies and lenses, so I'm borrowing their 50mm right now. The technicians there had a look for me and something is pretty wrong. I took the lens down to my usual shop and he's giving me a call if it looks like it will go over $100 to get it all cleaned up.
So, I think the ride in the mail that caused it's big filter ring dent caused the rest of it's problems too.

 

[paul ron]

It sounds like the problem is your lens. CLA can cost anywhere from $50 to $100.

At first your problem sounds like the mirror govenor was dead buit if it's working when the lens is off camera, the lens actuating ring is hanging the camera up.

Cock the lens off camer and see if it fires normally. When rotating the pins, they should be very smooth, rides on ball bearings.

Perhaps the bump it took in shipping may have jared the lens body appart, causing it to hang.

I wouldn't mind taking a look at it for you?

paul ron, NYC
automax1@juno.com