film plane and lose backs / revolving adapter

[nmcmahon]

I bought a new(used) rb a year ago because my old one had a lose back attachment mechanism. The revolving

adapter was not sercure tight against the rb body and as a result the film plane was slightly of parallel by a

few mm in the top right hand corner. My new rb has started to do the same and becomes and is becoming an issue

for critical work. It happens because the winding mechanism puts a strain on the revolving adapter locking

mechanism and a think the thin metal bars that secure the rev.adapt to the pins has become bent. Does anyone

have experience with this problem and have a fix. The metal used in the flimsy lock seems to be the problms and

wondered if anyone tried replacing it with a thicker piece that would not bend. It a fairly serious design flaw

with the otherwise great camera, so I guess many people have come up with their own solutions to this problem.

Any feeback would be gratefull

[paul ron]

Flimsey? I don't think so. Perhaps the problem is seals?... rough handling? But I have never seen this as a result of flimsey build.

 

There are adjustments for the back(s) tightness n alignment that a good overhaul will fix.

 

Can you post a pic of en example of what you are talking about?

[nmcmahon]

If you imagine pulling on the back of your rb film holder and the revolving adapter moving a couple of mm from the body noticably in the top right hand corner. you don't actually have to pull mine is not held tight to the body. I have taken apart the lock mechanism and looked at the metal strip that secures it to the pins and they are bent because the long thin peice of metal is flimsy and not strong. I know no way of tightening or adjusting the rev.adapt to the back. Having looked at the camera market at the piles of rb's they have for sale all of them have this problem to some degree, you can always push the back closer to the body. The rb is a great tough camera, its only weak points lie in it's back construction quality, in my opinion. Anyone else found this problem

[paul ron]

I have been repairing these cameras for a long time and your "weak mount" is the first complaint I've ever

gotten.

 

If you pull on the back, yes, it will move... that's not weak. At that point, it is concidered abuse not normal

use. No one ever pulls on a back so hard when shooting, that is not how pictures are taken unless you are

using the camera a climbing belay device, it's not a carabeiner. That is not the test of of a good camera.

Would you do that to a LF rig n say it's weak? NO!

 

So let me see what your pictures look like so out of critical focusing in the corner? I'm willing to bet the

seals are shot n the back isn't sitting flat on the mounts... unless you are pulling on the film crank as if it were

a car door?... but that would be moving towards the rev back n not away as you indicate as your out of focus

problem. So what is your winding method that you are pulling the back right off the body?

 

BTW don't crank the film winder so hard, don't let em snapback either, you will break the cast lever stop n

break the ratchet n pawl as well as springs n delicately adjusted levers. Like any piece of equipment... treat

it with care n respect, it will last a life time. Your camera is talking to you... listen carefully to what it's telling

you.

[nmcmahon]

As I have said before, Every rb I have looked at has this problem to some degree (thats around 10-15 I looked at when I bought mine second hand last year), in my case it sits about 1.5mm away from flush with the body. It's not the seals they are fine.

Yes of coarse if you pull it will come apart, I am not a baboon and I neither consider this normal usage but was mearly suggesting the action as an illustration to highlight my problem.

Admitedly my rb does not always sit in a comfy warm studio but follows me through all sort of terrains. I do not abuse it, but the camera back does not like being packed into bags and lugged around. This camera can take a lot of punishment but in this environment the one thing that is not up to the rest of the cameras build is the back.

I cannot overstate the fact that every camera I have looked at has this problem to a degree and it may not even be considered a problem to most.

If you have never encountered this problem then please refrain from telling me how to use my camera, I cannot treat it with any more care. Rb's have been given a new lease of life and are being used in situations they were never designed for i.e. the studio environment. I'm not complaining

I am not attacking the camera but merely suggesting an improvement or adjustment to keep this beast prowling.

In my opinion the metal strips securing the rev.adapt. could be stronger, has anyone done this?

[paul ron]

When you say the back is loose, it pulls away 1.5mm to cause an out of focus situation as a result of a design flaw... what am I supposed to think about how you handle the camera? I have seen all sorts of complaints but never in 40 years have I ever heard of anyone saying the back is pulling off because it';s a design fault. The Graphlok backs have been around for a long long time without fault. You say this seems to be a common condition on many cameras... sure you're pulling the back off the body using excessive force. They all do that, that's normal give. My findings over the years of repairing these RBs, I'd be willing to bet your situation is either a 30 year overdue repair or over zealous expectations. There are only a few instances this will happen n they all involve a repair, not a design improvement. The film back is only designed to support itself, not someone pulling on it.

 

I take my camera backpacking in the mountains upstate NY. I don't have a special camera backpack, it fits at the top of my camping gear in a regular backpack. My customers take their cameras to auto races, kayaking, backcountry skiing, traveling, ice climbing, remote parts of the world, studios... used by college kids, old folks, amateurs, pros,newbies, wanabees, neverwillbies... so what makes your situation special? This camera is meant to be used hard in all environments and is built like a tank for just this type of heavy use. It will not take kindly to abuse. It also demands certain regular maintenance which most amateurs can't afford to do. Most people treat them like their old 35mm cameras.. that's where you draw the line with pro equipment. Pros make their living with their equipment n can afford the upkeep. Don't get me wrong... it's not a house pet, n contrary to your misconception, it was never meant to be a lonely studio camera. It does have to be treated with care n respect, as you would with any camera, if you want it to serve for another 30 years. That's the main reason there are still so many in such fine condition. Now lets get to business....

 

The revolving back mounts to the body via 4 key pins that fit into holes n is locked in by a guillotine sliding plate that applies pressure to the pins n pulls them in via a wedging force. That lock lever on the bottom actuates the sliders. The rev back also has foam seals which are compressed n helps create a back pressure to keep the back snug to the body. If these seals are the wrong thickness or are worn, the back will not make a good seat. Are your seals worn, gummy or replaced with the wrong thickness material?

 

The film back sits on the rev back registered in a groove by the formed bar in the plastic film plane mask on the dark slide side. The Graphlok sliders pull the back onto the rev back via compressing the seals n also a wedging force as the slides are shifted, they pull in closer to the body. Are your seals worn, gummy, wrong material or the Graphlok loose on it's 2 shoulder screws or missing or wrong spacers under the screws... damaged in any way?

 

Take the rev back off the body with the film back attached... take a close look where the film mask meets the rev back's mask? How is the fit? Is it loose, wiggle around too much, pulls off using only finger pressure, normal winding pressure on the film lever? This is an indication if it needs seals or repairs or not.

 

If the back is moving around n not making good contact at the film plane masks, it is in need of an overhaul, seals n adjustments, not design mprovements, not a design fault I have ever heard of. This system has served many cameras for a good 4 or 5 decades. That is how the camera was designed n built n if you want to make the wheel rounder... go right ahead n let us know how it turns out? BUT... It's never been considered a problem with the RBs... most are that it's too heavy, clumsy, bad seals, someone forced the camera n bent or stripped internal parts, DIYer mess ups, lenses locked on, old shutters failed, new shutters fail more than older ones, broken mirrors, backs in need of repair or adjustment... it's the age of the beast n how hard a life it had.

 

Perhaps your lens mount is out of alignment n not parallel with the film plane? The camera may have been dropped sometime in it's life? Have you put it on a bench to check the square of the frame n parallels?

 

Where are you located? I'd be very interested to see exacly what you are talking about?

 

 

 

[nmcmahon]

Thanks for your detailed response,

It's easy to get carried away and misinterpertet peoples genuine aid, sorry.

I'm living in China at the moment, so I guess a visit would be out of the question. I would love to have it overhauled but no-one here is trained or really cares as they are very cheap to buy used.

From following your instructions I think I have noticed what is causing the problem. with the rb lens down on the table and the rev.back postioned on the body (not locked) all corners are flush with the body bar one the upper right. There is a certain mechanical springyness to it. The seals are in very good conition and seem to be a perfect factory one peice fit. In pushing the non flush corner to the body it emits a sringy squek. The two peices of metal that stike the rev.back when the rb is fired (mechanism that hits the back to register an exposure); the right hand side one does not depress as easily as the left hand side one and is exerting some force which is pushing the back out of line. (Sorry I hope this is clear, I can postpics at thge moment) I have no idea about the mechanics of this mechanism as I never opened the body up.

I'm 99% sure that this is the problem, the same force required to make the back flush is the same required to push this pin/edge back. Looks a little more complicated than I had first thought. Hope this sounds familiar to you.

[nmcmahon]

anonther thing i've noticed is that when the shutter is depressed but not fully depressed. the right hand side pin comes out of the rev.back by the same amount you depress the shutter release. The left hand only quickly shoots in and out upon actual firing. This leads me to think that the right hand side pin mechanism is set forward too far or is too highly or weakly sprung.

[paul ron]

I see the problem now. We are speaking in different languages n non-standard terms. It's hard to see you on the internet, we take so many things for granted. I apologize for being so abrupt.

 

So lets take another look at your backs.

 

Take the revolving back and film back off the camera. Mount the film back on the revolving back, locked in place. Looking into the revolving back with the attached film back... Are the masks meeting tightly at all corners? Does the film back wiggle in it's mount when locked down? Inspect the graphlok sliders carefully that they are pushed all the way over. Does the back feel tight in the mount using only finger pressure to pull on it? It will have a springy feel if you pull hard on it... that is normal give, that's to compensate for compressing seals. But the back should be a snug fit n the masks are touching.If this is so, the backs are fine. If they are not a snug fit then you need to do some more investigating. The Graphlok sliders are held in by only 2 shoulder screws with spacers inder each slider. You can take it appart but you won't find anything wrong there as they are never a problem, as long as the back is snug n the masks are meeting properly. The 2 end locks may need some lube every 30 years, but again, never a problem unless it's not firing.

 

Seals are good you say? Then you should feel a slight compression when mounting the backs in place. They tend to be slightly higher than the meeting surface n need to compress when you lock the backs in place to create the wedging force of the graphlok sliders. Both the revolving back n the film back have seals. Put a thin piece of paper, like a shopping store receipt, on the seal, lock down the film back. Gently.... Can you pull out the paper?

 

The 2 pins' travel you describe are normal. The right one travels with the firing button, the left shoots out upon firing.

 

The springy feel the unlocked revolving back is normal. It only has to be tight when locked.

 

Now, go shoot some pictures n tell me how they came out? It sounds like there is nothing wrong with your camera aside form your concerns about it's physical well being. The real proof of the camera is in the pictures, not it's appearances.

 

When you come to NYC, I will take a look at your camera.

[nmcmahon]

"The springy feel the unlocked revolving back is normal. It only has to be tight when locked."

 

This is the problem, it is not tight when locked. With the rev.back on the body there is an extra 2mm i can push the rev.back to the body using a little push. It can't be the stricking pin as nothing is there for it to push against, i realise now. Maybe the seals but I can't imagine they have any affect or provide enough pressure to push it out by 2mm.

 

Anyhow thanks for the help, It needs someone to take a close look I think.