Mamiya RB67 shutter delay

mkvrnn · Aug 22, 2015

I've just bought a Mamiya RB67 with 2 lenses.
One lens has fungus in it so I presume the lens is scrap, although the shutter in it works fine.
The other lens is optically fine but there's a delay of around 1 second when the shutter release is pressed before it actually fires, even though the mirror flips up straight away.
Does anybody know what could be causing this or how I could cure it? Alternatively would it be possible to transfer the shutter from my 50mm lens to my 90mm lens?

John Koehrer · Aug 22, 2015

Don't scrap the lens yet. You can kill the fungus by setting the lens in the sun for a day or two. It
won't remove it but will prevent it from getting worse.
Depending on where the fungus is it may just wipe off once you reach it. Even if it's etched the coating
it would be usable with little or no visible effects.

Regarding the delay, it's probably old lubrication, dried or thickened. and having the lens cleaned should fix it up,

Don't swap the shutter, swap the lenses, the elements should have the same diameter threads.
Unscrew each group and put them in the other shutter.

Xmas · Aug 22, 2015

Either strip both lenses or have them serviced they are built like auto wheels if you can jack a flat. Don't attempt to swap any parts...

Never known fungus to etch but fogging from lube etches every time! Remove fungus with ladies hand cream.

The foam in camera and back will be bad as well.

Google Jon Goodman

Trail Images · Aug 22, 2015

The other lens is optically fine but there's a delay of around 1 second when the shutter release is pressed before it actually fires, even though the mirror flips up straight away. Does anybody know what could be causing this or how I could cure it?

The lens shutter delay is usually just a required CLA. Just gummed up probably.

paul ron · Aug 22, 2015

cla is the shutter cure.

i read somewhere listerine mouthwash kills fungus. ive never tried it but they said the thymol is the magic bullet.

but, if the glass n coating is etched... well shoot with it n see just how bad it effects the image... you just may like a soft focus lens.

Kirks518 · Aug 22, 2015

I've only had one lens where the fungus etched the glass, and I couldn't see any issues in the final image. If you can get to it, as stated above, you should be able to just clean it off quite simply. Just don't over do it with whatever liquid you use. Just a drop or two on a lint free cloth or a lens tissue usually does it for me.

mkvrnn · Aug 23, 2015

Thanks for the replies everybody.

The next question is how do I dismantle the lenses to access the fungus or the shutters?

Xmas · Aug 23, 2015

You need a tube just small than 77mm and a used rubber glove.
The face plate ring unscrews and won't be tight with the tube covered by rubber glove as friction spanner.
You then need a file and a pair of scissors that span 76 mm or more open.
File the scissor points so they just bottom in the lens ring slots.
Hold the lens in wood vice with balsa wood and rubber pads again with your special tool the ring should undo easily.
The glass should drop out.
If a inner ring is special you will need to buy a lens spanner or send for pro service.
Getting grease out that is now wax needs effort like grease from frying pan but if you are practical is not impossible
The shutter blades and iris blades won't both be badly affected hopefully.

Sadly lots of people have sent me lenses and cameras with parts in labeled zip lock bags.
And I'm not the most dexterous person.

ladies hand cream contains something to kill fungus (1% NaOH!).
Zippo will soften grease and is not hydroscopic.
I use the merest trace of a PTFE auto grease on wearing parts applied with darning needle.

If you not desperately poor pro repair recommended.

Alan Klein · Aug 23, 2015

Has anyone actually tested to see if releasing the shutter when not in use actually helps maintain the shutter accuracy?

Trail Images · Aug 23, 2015

Has anyone actually tested to see if releasing the shutter when not in use actually helps maintain the shutter accuracy?

Alan, I've always kept mine in released mode when not using them. I'd be interested to hear if it is the positive method too. Not sure it maintains accuracy, but release of shutter tension can't be a bad thing I would think.

mkvrnn · Aug 23, 2015

Hi Xmas

Thanks for posting those instructions for lens dismantling - much appreciated. Unfortunately I'm stuck again!

I made a friction spanner and the first retaining ring unscrewed easily (the one bearing the lens name and number). That exposes 3 crosshead screws which retain the ring bearing the aperture numbers, which I have removed. This gives better access to the front element group which seems to be where the fungus is but I can't see how to remove it. I can see two little slots diametrically opposite each other, but these are underneath the front element. So the front element must be held in by some other means. Any suggestions?

I'm talking about the 50mm Sekor lens, by the way.

Finally, any suggestions for Mamiya repairers in the UK, preferably in the Midlands.

Xmas · Aug 23, 2015

The surround of the lens element may unscrew try with rubber glove. Though that might be tight.

But Google combinations of Mamiya RB67 50mm lens repair etc for less generic instructions or schematic etc.

I don't want to strip mine for fun...

Xmas · Aug 23, 2015

Newton Ellis in Liverpool are reliable but that is way north.

film_man · Aug 24, 2015

Alan Klein said:
Has anyone actually tested to see if releasing the shutter when not in use actually helps maintain the shutter accuracy?

Don't know but the manual says to fire the camera several times if it has not been used for a long time. Though it neither quantifies "several times" nor "a long time". So in the unlikely event that it is has been more than a month I will fire mine at all speeds and aperture settings a couple of times.

mkvrnn · Aug 27, 2015

I'm still struggling with both of these lenses so any further suggestions or help would be much appreciated.

(1) 90mm lens. I still have a delay of 1 to 2 seconds after pressing the shutter release before it fires. I tried the lens on another body and the problem is exactly the same, so it is something in the shutter mechanism within the lens.

(2) 50mm lens. The fungus (or whatever it is) is definitely on the inside of the front element. This is a single plano convex element which sits in front of the floating element group. It is fixed, but the floating group behind it turns with the focus ring. There is a bezel in front of the front element which I think must hold the element in place, but I can't unscrew it. There are traces of some kind of l clear cement which has come from the joint between the bezel and lens body. Any tips?

Xmas · Aug 27, 2015

mkvrnn said:
I'm still struggling with both of these lenses so any further suggestions or help would be much appreciated.

(1) 90mm lens. I still have a delay of 1 to 2 seconds after pressing the shutter release before it fires. I tried the lens on another body and the problem is exactly the same, so it is something in the shutter mechanism within the lens.

(2) 50mm lens. The fungus (or whatever it is) is definitely on the inside of the front element. This is a single plano convex element which sits in front of the floating element group. It is fixed, but the floating group behind it turns with the focus ring. There is a bezel in front of the front element which I think must hold the element in place, but I can't unscrew it. There are traces of some kind of l clear cement which has come from the joint between the bezel and lens body. Any tips?

I'll see if I can strip mine over the weekend.

But you need to down load the manual ... as

It is possible to arm and fire a lens off the body see manual

Unless the foam is good you need to sketch and replace...

I'd run a film through it with the 50 mm to see if everyone else is ok.

You need the manual for that.

Remove the name plate ring from the 90, if you can undo the ring nut the front group should remove and you can do a flush clean with a large pack of cotton buds can of zippo and pair of tweezers...

flavio81 · Aug 27, 2015

The 90/3.8C is really easy to strip down for lens cleaning (that is, to remove the front and back lens groups)

You just need to remove the front lens retaining ring and then the rest is just logical.

PRO TIP: If you don't have a lens spanner, a vernier caliper will be a perfect "makeshift" spanner for that lens.

Xmas · Aug 28, 2015

The second delay may be the iris blades rather than the shutter try firing wide open off the camera before dismantling.

flavio81 · Aug 28, 2015

To fire the lens, the camera rotates the two pins that are at the back of the lens flange. Any friction (i.e. caused by gunked lubricants) that reduces the speed of this movement, will cause a delay between any of these steps:

a. mirror up
b. lens stopping down
c. shutter closing
d. shutter firing (opening and then closing)

M Carter · Aug 28, 2015

Easiest RB lens element cleaning:

GET A SPANNER WRENCH… a $20 amazon/Ebay special is fine if you don't fix for a living.

Pull the rear element by using the flat-side of the spanner. Blow off any dust, clean it with 99% isopropyl or lens cleaner. (My go-to is ROR cleaner. And I always finish up with a CLEAN CLEAN CLEAN microfiber - only way I've ever gotten perfectly streak-free glass). You can clean the rear of the front element with the rear element out, and you can clean the front at any time. (You don't need to pull the front element, but it's easier to clean if you do).

To pull the front element - rubber plug (Fernco makes a rubber plumbing sleeve that's perfect) for the name ring. Three screws for the metal sleeve-thing. The element just unscrews like a jar lid. Makes it easier to clean the rear element.

Clean the shutter and iris blades with a small paintbrush and lighter fluid if they are sticking.

You can strip an RB right down to the shutter if you're mechanically minded, and give the shutter a soak. There's a youtube video of a guy doing that, but no dialogue so a little hard to follow.

Also, look into getting a seal kit from John Goodman - it's a fun afternoon and very doable to replace all the foam in the body.

mkvrnn · Sep 10, 2015

Still no progress with either of my two lenses!

(1) 90mm lens with the shutter delay.
The delay is the same both on and off the camera, and the aperture setting makes no difference.
With the lens off the camera, I cock the shutter by turning the two pins anticlockwise. I then press the
little pin and rotate the pins clockwise which closes the shutter and stops down the diaphragm. It's at this
point that the one or two second delay occurs, before the shutter actually fires, which suggests to me that
the problem is in the shutter mechanism?
I've managed to remove the rear element to gain access to the shutter blades which look fine - no sign of
lubricant. Should I try cleaning with lighter fuel or do I need to dismantle further?

(2) 50mm lens with possible fungus.
I've managed to remove the front element group complete. The problem seems to be on the rear surface of
the front element within this group. The subgroup behind this fixed front element is the "floating element"
part of this lens. The "floating" part rotates relative to the fixed front element. My problem is that I don't
know how to remove this fixed front element to clean it. Has anybody here actually done that job?

Thanks again for the advice.

StephenT · Sep 10, 2015

Please post how your removed the front element - I am going to have to do the same thing.

flavio81 · Sep 10, 2015

mkvrnn said:
Still no progress with either of my two lenses!

(1) 90mm lens with the shutter delay.
The delay is the same both on and off the camera, and the aperture setting makes no difference.
With the lens off the camera, I cock the shutter by turning the two pins anticlockwise. I then press the
little pin and rotate the pins clockwise which closes the shutter and stops down the diaphragm. It's at this
point that the one or two second delay occurs, before the shutter actually fires, which suggests to me that
the problem is in the shutter mechanism?
I've managed to remove the rear element to gain access to the shutter blades which look fine - no sign of
lubricant. Should I try cleaning with lighter fuel or do I need to dismantle further?

(2) 50mm lens with possible fungus.
I've managed to remove the front element group complete. The problem seems to be on the rear surface of
the front element within this group. The subgroup behind this fixed front element is the "floating element"
part of this lens. The "floating" part rotates relative to the fixed front element. My problem is that I don't
know how to remove this fixed front element to clean it. Has anybody here actually done that job?

Thanks again for the advice.

(1) yes, it seems it's a shutter problem; i'd try stripping down the lens until you see the actual shutter, then carefully applying a bit of lighter fluid to the part that seems to be "sticking". I would not directly add anything to the shutter blades, though.

(2) as far as i can remember, the "floating" part comprises most of the elements of the lens, save for the front element and one or two of the last elements. This means that the floating part should be removed as an entire group, and then it could be disassembled. Try disassembling the lens from the rear. Also, take careful note of the position of the floating block, because you don't want to miscalibrate it when reassembling it.

Mamiya RB67 shutter delay

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