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Markus
Tinkerer
Username: Markus
Post Number: 118
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 05, 2009 - 08:55 pm: | 
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This is starting to drive me mad...
I shot a roll of film with my Fed 2 and my brand spankin' new (for me) Jupiter 12 and noticed that I was getting somewhat uneven exposures. The negatives were a bit less dense on the left side of the film gate than on the right. I remembered that I had seen a tutorial on RFF and also Rick Oleson's notes on focal plane shutter speed testing with a TV.
With that I set out to fix this problem, and now I am stuck. I used a screwdriver that was slightly too wide to turn the shaft and now the locking nut and shaft are jammed together (on both shafts). Thinking that I could perhaps still get it to work even if I'm only able to tension by as little as 1/2 turns and no less than that (since the nut and shaft are jammed and I cannot move them relative to each other but I can still turn them as a unit and then lock the whole thing with the locking screw).
I have now spent way too much time staring at my old CRT TV through the shutter. I cannot get the two shutters to synchronize properly. I guess, to be more specific, I have a few questions:
- are the curtains supposed to accelerate as they move across, or should they move at a constant speed?
- at some tension combinations for the two curtains the shutter is very easily cocked. Should I aim for such a setting? It seems, however, that the curtains run too slowly, when I get to such a setting.
- When I hold the camera in such a way that I can see the entire TV screen through the open shutter on B, I seem to always see at least two stripes at the 1/500 or 1/250 setting. When I do the same with my Minolta X700, I only see one stripe. Is this correct?
- roughly how much tension do the curtains need. I read somewhere that around 2 to 3 turns is a good starting point. Is it really necessary to fine tune such that minute adjustments to the tension are necessary? How do I know when I am at a good configuration to start fine tuning?
I should maybe go and get another Fed, instead of testing my patience with this one. The problem is, though, that I am actually kind of attached to it, since I've already invested quite some time in it (cleaned and removed the vulcanite and gotten a new leatherette for it).
Thanks - Markus |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 877
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 05, 2009 - 09:46 pm: |
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Hi Markus:
- Yes, the curtains accelerate as they travel. This is why the diagonal band you see on the CRT screen is slightly curved - if they traveled at a constant speed it would be straight. This does not matter, as long as the width of the band is constant from one end to the other.
- It doesn't matter whether you see 1 stripe or 2. The curtains in the FED travel more slowly than those in the Minolta, and this is why you see more than one stripe in the FED shutter. The only thing that matters is the constancy of the width of each stripe, and to a slightly lesser extent the width itself (thinner meaning a faster speed and fatter meaning a slower speed. With the FED and Minolta shutters both at 1/500, the width of the stripes should be the same in both shutters, even though they will be at different angles across the screen and have different amounts of curvature, and you might even see a different number of stripes.
- Without having factory specs available (which I usually don't), I like to set the shutter with just enough tension that the curtans travel reliably. This may be a bit below the factory spec, but it is a bit easier on the springs, easier to wind and sometimes a little quieter and smoother in operation. I don't want it so low, though, that on a cool day the shutter hangs up ... it needs enough power to run with confidence. Once you find this minimum threshold, you can adjust by speeding up whichever curtain is running slower than the other. |
Markus
Tinkerer
Username: Markus
Post Number: 119
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 06, 2009 - 08:32 am: |
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Rick, thanks for your reply! I will try again, tonight. Also, I remembered that I have a Fed 5 (got it as a de-facto rear lens cap with my I 61). Looking at the shutter operation on that camera, I think I have been trying to adjust the Fed 2 with too little tension on the springs. The Fed 5's curtains are quite snappy and I now have a reference to work with when using the TV as a shutter tester. The Fed 5 has the same top shutter speed as the Fed 2, unlike the Minolta.
I will report back... |
Lucas
Tinkerer
Username: Lucas
Post Number: 92
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 06, 2009 - 12:07 pm: |
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I got one recently and after just cleaning the spindles the curtains sit on, I was surprised at how lightly the curtains zap across the filmgate. There does not appear to be a lot of tension on the curtains and the shutterspeeds are within tolerances. I would make sure the spindles run nice and lightly before cranking up the spring pressure. |
Markus
Tinkerer
Username: Markus
Post Number: 120
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 06, 2009 - 03:20 pm: |
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Lucas, I am curious exactly how and what you cleaned. Did you have to disassemble the shutter to clean the spindles, and by spindles are you refering to the two rollers on the left of the film gate when looking through it from the back?
Thanks - Markus |
Lucas
Tinkerer
Username: Lucas
Post Number: 93
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 07, 2009 - 06:32 am: |
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No major disassembly. The curtains were very sluggish and the second one getting hung up on 1/25 and B. I used a very small drop of engine degreasant to get the gummed up original oil to loosen up and then added just one drop of watch oil and exercised the shutter a a bit. One spindle is on the bottom of the camera where you see the release. The other on the top towards the right where the shutterspeeds are set.
I did not need to take it apart a lot, I used most of the time to realign the rangefinder and to straighten the rangefinder arm in the body that had been bent.
The shutter started up immediately and runs very light and smooth and the release button also became much smoother and lighter.
If the focusing is stiff on the lens, same procedure. One small drop of engine degreasant, exercise, three drops of watch oil, no disassembly at all.
http://farm4.static.flickr.com/3504/3465692571_fe6ac46eb0_b.jpg |
Markus
Tinkerer
Username: Markus
Post Number: 122
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 07, 2009 - 03:37 pm: |
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Thanks for the info, I had cleaned and lubricated that part already without effect, so I decided last night to take the shutter apart and clean the whole thing thoroughly. Maybe I'll get it back together on the weekend. |
Lucas
Tinkerer
Username: Lucas
Post Number: 94
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 08, 2009 - 02:01 pm: |
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The original hardened lubricants were very tenacious. I normally use lighterfluid to clean but this time had to resort to something with more oomph. Perhaps that is of help to you ? |
Prasanna
Tinkerer
Username: Prasanna
Post Number: 13
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 24, 2009 - 09:12 am: |
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The Fed curtains run very smoothly if the spindle anchors and gears are clean. The curtains ought to be taut to the extent that when you press gently from the rear frame they should snap back to position and not be flaccid. Please make sure that you don't press with your nails or any sharp object, only your soft-fleshy fingers!  I have four Feds, 2,3,4&5 and I have lubed and adjusted the curtains on all with CRT TV. They run very smoothly and with less noise than what the Zorkis do. The FSU cameras seem to take a little more lubrication than cameras from other countries. It could be just my impression, though. Regards, subbarayan. |
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