Shutter speed at slow speeds

[wclavey]

I have a Polaroid Copal shutter I purchased used. When it is laying flat on the work surface, the 1/2 and 1 sec speeds are eratic. I just figured that it would be of limited value, but what the heck, I only paid about $15 for it anyway.

Then I noticed that if I held it perpendicular to the work surface, as it would be mounted on a camera, the shutter speeds were fine. I exercised the shutter numerous times in the vertical position, then put it flat and the shutter speeds went off again.

I opened the shutter and I can see what looks like the problem but I do not know the technical names to describe what I see... there is a lever that is tripped and slowly rises to the top that determines how long the shutter stays open. When the shutter is flat, this lever does not return to its normal resting position, but when it is vertical, it does return.

I used a little Ronsonol on a Qtip to clean the mechanism there. It worked fine when wet, but returned to the same problem after drying. Having read all the warnings about not using oils and only oiling some parts, I am not sure what to do next.

I use a lot of slow speeds on 4x5, so I hope to be able to fix it, but like I said, I will not lose too much sleep over a $15 shutter.

 

[Jim Noel]

It is time to invest another $50 in the shutter. Send it to Carol at Flutot Camera Repair and it will be like new.

Jim

 

[David A. Goldfarb]

Ronsonol on a Q-tip might not be enough.

I haven't worked on one of these, so this is a guess--

If the shutter has all metal parts like most synchro-compur shutters, you can open it up and soak the whole thing in naphtha to flush it out. When it's dry, set it on a slow speed and there should be a group of rapidly spinning gears, which is the slow-speed retard mechanism. A drop of fine machine oil like sewing machine oil should keep them moving.

 

[Roger Hicks]

Slosh it out in trike (trichloroethane) or any similar major-league solvent -- no need to disassemble. Then run it 'dry'. The life will be slightly reduced (8-80 yr instead of 10-100) but I'd hesitate to use even sewing machine oil: only watchmakers oil, and even that ain't essential. I have just done this with a Protor-Press.

BE SURE that the separation on whatever lens you install is appropriate.

Cheers,

R. (www.rogerandfrances.com)

 

[wclavey]

Thanks for the info. Now 2 more questions: (1) Where would one go to purchase Trike (or another solvent that could be used)? Ronsonol is my sole choice to date. (2) Explain more about the separation - - I assume you are talking about the distance between the cells. My (obviously mistaken) action would have been to screw the lens cells in both the front and the back as far as they go. How would I check for something to indicate that it isn't correct... try to focus and it won't work?

Thanks.

 

[John Koehrer]

wclavey,
I've used coleman fuel for this. ie Naptha.
Evaporates very quickly in use.
Only problem if you don't camp is that it comes in gallon cans at Target.

 

[glennfromwy]

Trichloroethylene is available at auto parts stores in the form of liquid rubber buffer, for tire repair. I have a quart of it that has lasted me for quite a few years. Liquid buffer may use a different chemical now. I'm not sure. You would have to read the label. The stuff works great. Leaves no residue and dissoves gunk that naptha won't.

 

[Roger Hicks]

Trike is next to impossible to get in the UK, but quite easy in France; I don't know about Texas. It is sold for degreasing metal parts, so another possibility, as well as auto parts, is a do-it-yourself store. You may have to sign the poisons register. It's perfectly safe if used with respect (in a well ventilated room, not dabbling your fingers in it -- I use vinyl surgical gloves) but you can pass out from the fumes and it may be a carcinogen, I've forgotten. You need lengthy and serious exposure, and bad luck, to have any ill effects.

I assume you will start out with a working lens in a broken shutter. Measure the distance from the front to the back (the length of the lens, if you like) with vernier calipers or a micrometer. When you screw the lens into the 'new' (Copal) shutter, make sure the distance is the same. If the separation between the two cells is different, the lens will still focus, but there will be a significant loss of quality.

I once bought a 300/9 lens in a (defective) shutter and found that the image quality was lousy too -- needless to say, it was cheap. I went to the manufacturer's web-site; found the specified front-to-back length of the lens; discovered that the lens I had just bought was about 0.7mm too short; and when I re-shuttered it, made sure that the overall length was as on the site. Result: the lens was transformed, and the shutter worked too.

For adjusting separation you can use shims or (with some shutters) it's possible to screw the front of the shutter in and out. There's a sort of scalloped surround to the hole in the front, with a screw in one of the scallops to secure it. Undo the screw; screw the scalloped bit in or out; refit the screw.

Cheers,

Roger (www.rogerandfrances.com -- and you've just given me an idea for the free 'How Do I...' modules in The Photo School: thanks)

 

[Neil Miller]

I used to work in a metal fabricating factory many years ago, and we used 'trike' in a vat as a degreaser for metal objects. It was out in the sticks and poorly run, and the trike vat - which was heated - regularly overflowed. Anyone in the immediate vicinity would pass out, or become dizzy and appear to be drunk. If one had consumed alcohol the previous night the effects were much worse, and I remember reading of several murders involving subjecting unconscious drunk people to trike fumes by placing a trike soaked rag over their faces.

There is a recognised symtom - 'degreasers flush' - a skin rash that was common among metal degreasers who also regularly consumed alcohol. Increased rates of liver and kidney damage and cancer have also been reported among people regularly exposed to trike.

As Roger says, though, using small amounts in a well-ventilated area now-and-again is probably perfectly safe.

I have rescued a few old shutters by removing the cells and soaking the shutter in lighter-fluid. The small lighter fluid cans also have a nozzle which can spray a thin stream of liquid to dislodge small particles. The amount of dust, grit and metal filings that sometimes comes out of an old shutter can be quite surprising. The hazchem info on the cans is a bit alarming, but these days it seems like everything is out to get you!

Like you say, Westley, I have noticed that after drying the mechanism sometimes binds again, in which case I apply a tiny amount of 'nyoil' (gun oil) to the pivoting parts of the escapement, which usually does the trick. Only a tiny dab is necessary - the tiniest drop from the end of a needle is enough. If you have to oil much more than a few gear spindles, though, the shutter is probably too worn to repair by a DIY-er.

Regards,
Neil.

PS: The fastest and lowest speeds of most old shutters are usually way-off.

 

[Jim Jones]

Long ago we used carbon tetrachloride in teletype and typewriter cleaning. Because of safety problems, we switched to trichloroethane or trichloroethylene. There were safety concerns with them, too. Now, 50 years later, none of them seems to have had any permanent effect on me. 90% isopropyl alcohol is readily available, and works well where one can blow away the residual water. Pure acetone from a manicurist is sometimes better. The alcohol is also handy for quick drying photo film.