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07-21-2011, 03:38 PM   #1
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Repair shutter capping

So I bought this new (to me) camera off ebay for 16 euro (Spotmatic SP, FYI), received it, put a test roll through it, and had some massive shutter capping at 1/1000. The first curtain's tension is so weak, that it actually forms some waves while it's cocked. Mailed the seller, currently waiting for his response, but I really wouldn't want to send it back, but rather keep it and have it repaired or repair it myself if I can. I am wondering what's to be done actually, I've read about removing the bottom plate and spinning some small things to increase curtain tension, but I'd really like to be sure of what I'm doing before even starting. By the way, how is the speed of, say, 1/1000, calculated? I mean, 1/1000 of a second (0.001 s) starting from when and ending when? From when the first curtain opens until the second closes? Because I think I can make a pretty precise shutter speed test using nothing more than a microphone and Audacity, playing the shutter sound in slow motion and calculating the actual length of the exposure.



07-21-2011, 04:29 PM   #2
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Such shutter capping shows the curtain speeds are not the same, but doesn't necessarily mean the tension is off. It may be dragging from dried, gooey lubricant or some other mechanical problem. (The wavy curtain may well indicate an issue with guide rollers or curtain ribbons.) Likewise sometimes curtains speed up when last traces of lube dry out.
Rather than just cranking in more tension, you should clean and lubricate properly before adjusting curtain speed. There are several books and training materials that show how to work on the Spotmatic shutter, and these are nice cameras with which to learn camera repair.
An old analog (not digital) TV is a great shutter speed tester. If you've got one that's still usable on cable or with a DVD player, remove the lens and back and look through it from far enough back that the TV fills the frame. At high speeds you will see a narrow diagonal band of light that is narrower at faster speeds; so you can judge consistancy from side to side as well as overall speed. Look at each speed a bunch of times to evaluate consistency.
If you don't want to get that deep in a new hobby, Eric Hendrickson can do a great CLA to restore it at very reasonable cost - and they are worth fixing right.
07-21-2011, 05:32 PM   #3
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On a focal plane shutter, such as the Spotmatic's, the two curtains travel at a constant speed. The "shutter speed", or exposure time, is really a function of the difference in starting times of the two curtains.

On the Spotmatic, speeds or 1/60 second or longer, the first curtain fully opens before the trailing curtain begins to close. At speeds of 1/125 and higher, the trailing curtain begins to close BEFORE the leading curtain is fully open. Just as an aside, this is why you can't use electronic flash at speeds higher than 1/60 on a Spotmatic.

The higher the speed, the less the time between the beginning of the opening of the leading curtain and the beginning of the closing of the trailing curtain. This results in a moving slit that traverses the film plane. At 1/125, this slit is almost the full frame. At 1/1000, it is 1/8 inch or less. In all cases, the speed of the curtain movement is the same.

Because of this variable-width slit, any given spot on the film is exposed for only the time specified by the nominal shutter speed. It may take 1/60 second for the shutter to complete its travel, but each point on the film received only 1/1000 second of exposure.

If you decide that this adjustment is beyond your abilities, or if you just don't want to risk screwing it up, there's a guy in Tennessee named Eric Hendrickson, who is THE goto guy for Pentax film camera repair. He is a former repair tech for Pentax who now does repairs in his home. His website is http://www.pentaxs.com/. Everyone who has ever had him work on their cameras reports that he does quality work at a fair price.
07-21-2011, 10:27 PM   #4
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QuoteOriginally posted by noblepa Quote
there's a guy in Tennessee named Eric Hendrickson
The OP lives in Romania...that would be eastern Europe and not particularly handy to Tennessee. Other than that, Eric is the man!


Steve

07-22-2011, 09:04 AM   #5
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QuoteOriginally posted by stevebrot Quote
The OP lives in Romania...that would be eastern Europe and not particularly handy to Tennessee. Other than that, Eric is the man!


Steve

Oops. I didn't read carefully enough. The mention of the price in Euros should have been a tipoff.

Mea culpa!
07-22-2011, 09:07 AM   #6
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QuoteOriginally posted by noblepa Quote
Oops. I didn't read carefully enough. The mention of the price in Euros should have been a tipoff.

Mea culpa!
Haha, you were close, but that's Latin! Luckily I know a trusty repairman in town that I think I will send the camera to eventually, but I need the money. Even if I get a full refund it won't be enough for a CLA, so...
08-03-2011, 02:40 PM   #7
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Here's my problem, this time better documented.












And a video of the shutter at 1/1000:

I think it's clear that the camera needs a CLA, the question really is if I should attempt to do it myself. I have just noticed that sometimes the meter switch doesn't return to its normal position, and I'm thinking of pouring some rubbing alcohol in there.
08-03-2011, 03:33 PM   #8
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QuoteOriginally posted by kcobain1992 Quote
I'm thinking of pouring some rubbing alcohol in there
Lighter fluid ("Ronsonol", naptha, white gas) is the usual solution, used with discretion as a flood and wicked away with blotter or paper towel.

Just looking at the shutter curtain, I concur that it needs work. Broken ribbon perhaps?


Steve

08-06-2011, 04:45 AM   #9
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Well, wow. Brought the camera to my local repairman, and he refused to open it, and said that although it is clear that it has been opened before (see picture "Halfway 1"), the shutter will repair itself with usage. He showed me that it already seems to have stopped capping, although I can't be sure until I run another roll of film through it. My question now is: is this a healthy way of treating the camera? or should I gather more money and perhaps send it abroad for a complete overhaul?
08-06-2011, 08:36 PM   #10
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QuoteOriginally posted by kcobain1992 Quote
Well, wow. Brought the camera to my local repairman, and he refused to open it, and said that although it is clear that it has been opened before (see picture "Halfway 1"), the shutter will repair itself with usage. He showed me that it already seems to have stopped capping, although I can't be sure until I run another roll of film through it. My question now is: is this a healthy way of treating the camera? or should I gather more money and perhaps send it abroad for a complete overhaul?
While there is some truth to what the repairman says, it still would not hurt for it to be cleaned and lubricated properly given its age and problems.
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