RB67 Pro S Cocking Lever Problem

[woodspiral]

Dear RB fellows,

Just joined the RB67 club by buying a Pro S with a Sekor 65mm lens off Ebay from Japan for £178+£58shipping+£50 something for taxes. Lovely condition but there's an issue with the shutter.

I shot a roll of Ilford PanF and took one shot with my 500mm lens (purchased at Mr Cad in London) and 9 shots with the 65mm. The 500mm shot was fine, but the 65mm were completely black. Good news, is that the light seals on the back seem intact as no signs of light-leakage.

My first thought was the shutter in the lens has got stuck, so I took the back off, set the f-stop to 4.5 and the exposure to 1 sec and pointed the camera at some bright light source. I generally did not see any light, except when the lens was taken off and put back on. I thought from this that the shutter was just firing seldomly and intermittantly, however;

I ran some more tests this morning and it looks like the problem may be the body not the lens, or perhaps a combination:

1) When the lens is off the body, the lens shutter works OK, except for the first one or two 'exposures'. Once it starts to work it seems to work 100% of the time.
2) After putting the lens back on the body, the shutter release button operates the shutter correctly ONCE, After cocking the shutter with the lever, the shutter does not open, ever it seems. Except one time, when it may have done it twice.
3) Using a double cable release makes no difference - same behaviour.
4) The high pitched whirring sound of the timer in the lens can be heard even when the shutter doesn't open.


I would conclude from this, that somehow the cocking lever on the camera body does not cock the shutter properly in the lens.

I called Camera City in London and they couldn't offer any advice over the phone - they need to see it. If anyone here is in London, is that the place you would go to for advice/repairs?

I've opened a query with the seller, so they may pay for a repair if necessary.

In the back of my mind, I'm thinking that I'm doing something wrong, perhaps. The mirror up selection on the lens is off. Is there anything else that might explain this behaviour?

Thanks!

 

[Trail Images]

You should be able to test the lenses and camera body separately. The camera has no shutter, only the mirror that goes down during the cocking process and then goes up when the mirror release is triggered.
The lenses have a N & M with a small button that can be pulled out and turned for mirror lock up usage. The lenses can be cocked manually off the camera and released by a silver small button on the back of the lens near the lens cocking levers. Once you've learned the process of testing the two items separately you will possibly see what maybe the issue.

If for some reason you've got the lenses set in the "M" mirror lockup mode, then merely triggering the main front release button will not operate the lens. The lens will not release the shutter until you trigger the "M" mirror lockup button. If you want the mirror and lens shutter to release at the same time off the main front silver button, then leave the lenses on N.

I was surprised at your comment about the 500mm lens. Your title states you bought a Pro S body? If so the 500mm should only fit the Pro SD body. The Pro SD has a larger opening on the front to accommodate the 75mm Shift / Tilt lens and the 500mm lens. If you did in fact get the Pro SD body then the 65mm lens should require the use of the lens sleeve or collar designed to use with standard Pro and Pro S lenses.

If you find the lens is intermittent and sluggish with releasing of the shutter it is a CLA issue. I bought a lens a year ago and within two outings of hit and miss exposures I realized it was only operating half of the time. After sending it in for a CLA it has worked flawlessly for several months now.

This link maybe of help.
http://www.cameramanuals.org/mamiya_pdf/mamiya_rb67_interchange_lenses.pdf

 

[woodspiral]

Thanks, Trail Images,

I know how to test the lens separately, and that's what I was doing in point 1) in my OP. Doing that seems to indicate that the lens is OK. I don't know how to test the body separately.

The mirror up selector was not selected during the tests. I did some separate tests with the selector and it seems fine.

> I was surprised at your comment about the 500mm lens. Your title states you bought a Pro S body? If so the 500mm should only fit the Pro SD body.

That's not true - there were two types of 500mm lenses produced, mines a C type - see http://rb67.helluin.org/lenses/.

> If you find the lens is intermittent and sluggish with releasing of the shutter it is a CLA issue. I bought a lens a year ago and within two outings of hit and miss exposures I realized it was only > operating half of the time. After sending it in for a CLA it has worked flawlessly for several months now.

I'm taking it to an expert tomorrow for advice, they will offer a CLA if that's required. I think the malfunction is systematic rather than intermittent.

Great link - thanks!

Best wishes,
David.

 

[Trail Images]

David, good luck with repair update. Please leave a follow up fix noted and what was found. Also, thanks for the info on the 500mm item.....I learned something new today.....thanks!

 

[woodspiral]

Update: I got a quote of £227 + VAT (20%) for the repair - Ouch! That's more than what I paid for the camera. The shop said the problem was with the body (see below, however!). I let the Ebay seller know and he said he would find a replacement body instead.

As I've got a big trip coming up I wanted to get this fixed quickly, so I thought "I wonder if I could buy another RB67 here in the UK for around £227?". Sure enough I found one, recently serviced with a 6 month guarantee for £285 so bought it! It has a prism viewfinder (my original one has a waistlevel finder), and a 90mm lens (instead of 65mm). So I now have two backs, two bodies, prism, waist-level finder a good 90mm and a potentially dodgy 65mm...

Having two sets of equipment allowed me to do some further tests. Call my first camera A (+ 65 mm lens) and the one I bought recently B (+90mm lens). 90mm lens works fine on and off B's body - that is, I can cock and fire the shutter without issue. 65mm lens will work off the body but it will not open when attached to body A or B. Moreover, body A will also operate the 90mm lens properly - that is it will cock and fire the shutter properly. This would indicate that it is a problem with the 65mm LENS not A's BODY, as indicated by the repair shop.

Minutely inspecting the backs of the two lenses, I see they both have a circular 'lug' in the centre of a channel, perhaps 3mm in diameter. This 'lug' has a small hole (perhaps 1mm or less) in the centre. The 90mm lens has the lug perfectly centered in the middle of its channel, wheras the 65mm lens the lug is off by about 0.5mm to the right. I wonder if this tiny misalignment is enough to cause a problem?

I'm trying to find a reasonable price for someone to do the repair, but the cheapest I can find is £165+parts which is going to be too much for the seller. I have asked if he can send me a replacement.

I would potentially be prepared to have a go at fixing this myself if I had some more information - are there such things as service manuals around?

 

[Trail Images]

Woodspiral, I'm headed out the door so no time to look at my lenses, including a 90 & 65. But when I get time I'll look to see if I can visualize what your talking about. I truly think you're on to something. I've seen service manuals on line at eBay, but not sure I recall a specific manual for lenses. The upside is there is still A LOT of RB units and service outlets around. So, I'm sure you'll get things working without a lot of heart burn.
Thanks for sharing this update, it helps us all investigate things to make sure what the possibilities are when something goes wrong.

UPDATE
I looked at both my 65 & 90 and they seem to have this "lug" you mentioned in the same identical spot on both lenses. I suspect you've resolved the mystery and it is a matter of trying to repair it or send out for repair. It's hard to say whether something has turned, a plate it is attached to, or it is just slightly bent from misalignment when mounting or dismounting from the camera body. It is so small and tucked away I cannot imagine it being dropped and hit, so, again maybe just a rough handling on the hookup at some point. Being so small it might be an easy tweak if one knew what it actual does in the marriage process between camera and lens. Probably a job for the professionals if the lens otherwise is in excellent shape.

Keep us posted when you've worked things out.

OK..... looking at this "lug" once again it appears to be right behind the lens red centering dot on the front. If it's what you're referring to. In fact that looks to me as though it must meet the camera mounting ring perfectly in order for the lens to be positioned correctly overall. So, if that is not in the right place then the lens to me looks like it could not be mounted correctly at all, unless forced into place one time. Which could be the original issue overall.

 

[CarolynArteaga]

Great going