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Hollenbj
Tinkerer
Username: Hollenbj
Post Number: 32
Registered: 03-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 25, 2012 - 12:43 pm: | 
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Hi forum,
I have a Canon 7 rangefinder that I'm cleaning and fixing to be a primary user. I see that I'll need to deal with the light meter (if I feel necessary), but that's for later.
My problem now:
I checked the shutter at each speed. Speeds 1/60 up to 1/1000 seem good by ear. But, speeds 1/30 down to 1 second have an odd "after sound". The curtains open for an appropriate interval (that's good), but immediately after the 2nd curtain closes, there is a sound like a bouncing spring that diminishes after about 4 or 5 "bounces". Very noticeable. The sound is most pronounced for speeds 1/30, 1/15, 1/4, 1/2, and 1 second. This is not the slow speed escapement; this happens after the 2nd curtain closes. What is this? Any ideas? I need to address it just because its so annoying (even though the slow speeds seem accurate).
Thanks everyone!
jeff. |
Finnegan
Tinkerer
Username: Finnegan
Post Number: 152
Registered: 09-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 25, 2012 - 05:29 pm: |
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It happens in the Pentax Spotmatic too.
Boing, boing boing. |
Hollenbj
Tinkerer
Username: Hollenbj
Post Number: 34
Registered: 03-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 26, 2012 - 11:44 am: |
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Oh yes, I've had SLRs with a bouncy mirror. Spotmatic was probably one of them. I know how to deal with that.
The Canon 7 is a rangefinder, much like a Leica, but then again different. Focal plane shutter, but no mirrors (well, except the rangefinder). I'm really not sure what's making the bouncy sound on this camera. I really like to know what to look for before I open things up.
Does anybody know? Guesses? |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1206
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 27, 2012 - 08:29 pm: |
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I think you may be hearing the slow speed escapement resetting itself after the exposure. The gears spin during their function of delaying the closing curtain, and have to return to their starting position afterwards. Some cameras have a one-way clutch in the escapement so that the return is silent; but sometimes the clutch becomes sticky, and the camera still functions normally but you hear the escapement buzz as it returns. |
Hollenbj
Tinkerer
Username: Hollenbj
Post Number: 36
Registered: 03-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 27, 2012 - 10:02 pm: |
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Hi Rick,
Nice to hear from you.
Not a buzz. This really sounds like a boing. Think spring or ping pong ball. I had an SLR some years ago that had the same after shutter sound, but I thought it was the mirror bouncing. This really sounds like that, but believe me, there's no mirror on the Canon 7.
As you know, I like to know where to find my problem before I open things up. That helped with my Canon IIF (although I've made a new problem with that one somehow). Would a "broken" brake mechanism make such a sound?
I really wish I could provide a recording. Can I upload an .mp3 on this forum?
Thanks!
jeff. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1207
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 28, 2012 - 06:39 am: |
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There aren't a whole lot of alternatives; only moving parts make noise, and in a Canon 7 the only moving parts are the shutter curtain drums and the slow speed escapement. So I'd think it would have to be one or the other of those. The fact that the slow speed escapement is engaged from 1/30 down and that this is when you are hearing the noise seems to point in that direction (plus, the thought of the closing curtain bouncing 4 or 5 times would be pretty extreme). So that's still where I'd look, buzz, boing or otherwise.
: ) = |
Finnegan
Tinkerer
Username: Finnegan
Post Number: 153
Registered: 09-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 28, 2012 - 12:09 pm: |
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Not a mirror bounce. Set any Pentax Spotmatic or K1000 to 1/30 or 1/60 and you hear the bouncing ball bearing. Boing, boing. At slower speeds you don't hear it so I never considered it part of a slow speed escapement. Also audible in the manual Fujica slrs. I envision a ball bearing bouncing on top of a spring in a cylinder every time I hear it. I figure horizontal cloth focal plane shutters were designed once then copied by everyone so that is why have cross branded boing boing. |
Hollenbj
Tinkerer
Username: Hollenbj
Post Number: 37
Registered: 03-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 28, 2012 - 01:15 pm: |
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Thanks folks,
Well, I agree there aren't many places to look. I'll start with the slow speed escapement. I know its not the curtain bouncing (yes 4-5 time would be extreme) because I checked that.
It does sound like a ball bearing bouncing on a spring. Its certainly annoying. Finnegan, did you get rid of the Spotmatic and/or Fujica? If not, how do you live with that noise?
I have to finish my Canon IIF (another post here) before I put the 7 on the bench. I'll report what I find when/if I find it.
Thanks again.
jeff. |
Old_school
Tinkerer
Username: Old_school
Post Number: 148
Registered: 04-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 28, 2012 - 03:40 pm: |
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J: At the top of the page click on the manuals & get a copy of the 7. On pp 8.TIF you will find the retard assembly & where it resides in the camera. On the lower right side is the second curtain & that wheel driven by it with a post on it disengages the slow speed mechanism that allows the reset for the next setting. So, the sound you hear is the gear segment zipping into place. better image in pp 11.TIF. When they are properly adjusted & lubricated you should not get that extra reverberation sound. Clean the retard (pull it out & clean & re-oil plus the rest the rest of the shutter. Good Luck! |
Hollenbj
Tinkerer
Username: Hollenbj
Post Number: 38
Registered: 03-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 28, 2012 - 04:25 pm: |
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Old school,
Thanks, that's very helpful. I think I see the culprit in the diagrams.
I need to clear the Canon IIF off first. I didn't want to disassemble that one any further than necessary. It looks like I did something during my repair of the advance shaft: Now when I wind on (without the film advance clutch in place) if I let go it will snap back to uncocked position. Weird, because I don't remember doing anything to cause this new behavior.
So it seems that the spring is now engaged during the cocking process when it wasn't before. My guess is there are latches somewhere that aren't engaging/disengaging like they're supposed to. Where would those be located? I hate to go on a wild goose chase because every entry to a new part of the camera is an opportunity to mess things up.
Thanks again for your help. Patience and assistance from this forum will prevail.
jeff. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1208
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 28, 2012 - 05:15 pm: |
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I've had this happen in something ... can't recall what the camera was. It had a sprag clutch inside one of the gears so that it would engage going forward and then freewheel going back - made the return both silent and instant. The sprag clutch got dirty, and then it didn't disengage; continued functioning fine except for the noise after exposure. |
