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Gordon Zola
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 30, 2005 - 06:25 pm: | 
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I have this synchro-compur on the 2,8F that gives strange shutter speed readings... considering that it has been CLAed by a so-called Rolleiflex specialist (in Switzerland).
I always doubted that something must be wrong; the 1 second just sounded too short.
Anyway, my readings (taken with a phototransistor in conjunction with a sound card ) show following discrepancies:
1 sec = 840 milliseconds (ms)
1/2 = 480 ms
1/4 = 215 ms
1/8 = 100 ms
1/15 = 7 ms !!!!!!!!!!!!! (should be rather around 60 ms)
1/30 = 29 ms
1/60 = 18 ms
1/125 = 9 ms
1/250 = 3 ms
1/500 = 3 ms
Basically, it runs a little too fast, except for the top speeds, and it runs pretty ok around the 1/125 speed.
But 1/15 is definitely way out of place. It runs faster than the 1/125!
While I know that mechanical stuff can't be as exact as electronically driven shutters I think that this one's just over the tolerance.
So I was just wondering if anybody could make a diagnosis of this illness, since I myself am into tinkering with mechanical cameras.
Nothing important really, I was just wondering. The camera is now with a Rollei repair center for a check-up. So I'll be ok. I love tinkering and repairing old cameras, but I won't (for now) touch valuable stuff.
Any comment or question welcome.
Gordon |
rick oleson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 30, 2005 - 07:01 pm: |
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It just needs cleaning. The delay sector isn't resetting at the 1/15 setting, probably because it's dirty. It's probably doing the same thing at 1/250. No big deal, but it doesn't seem like it should be happening 2 years after a good CLA. |
Gordon Zola
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 30, 2005 - 07:18 pm: |
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Thanks for the information, Rick.
What would you say about the other readings? In other words, when I do this kind of testing, what is the tolerance? I mean, is 840 ms precise enough for 1 second on this kind of shutter or can it be better than that? |
Robert
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 30, 2005 - 10:44 pm: |
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Mets new camera standards. |
rick oleson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 07:39 am: |
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840ms is about 1/4 stop off, close enough for most photographic purposes; it could be made closer but most people would probably call it close enough.
At the higher speeds, such precision becomes impossible with a leaf shutter. This is because at 1/500, the time the shutter spends fully open is virtually zero; it is always in a constantly-changing partially open state. Calibrating it to deliver an exact light equivalent at full aperture is a complex process involving an oscilloscope and integral calculus.... which become rather futile anyway because the whole relationship is diffent as you stop down, giving an effectively longer exposure at each smaller stop. With a leaf shutter, it's really best to get the speeds running in proper proportion and see that it produces good results on film; you can drive yourself crazy trying to be "technically correct" without ever achieving it.
: ) = |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 08:29 am: |
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If I remember it correctly the Compur repair manual mentions that 1/10 or 1/15 can be adjusted separately, with minor effect on the other speeds. This speed is somewhat difficult to adjust on many shutters since it is the fastest speed running with the escapement pallet switched on. If the shutter cam (or the cam follower pin) is slightly misadjusted the shutter will run almost at the top speed, i.e. as if the cam follower of the escapement is in its extreme position. On Compur shutters speeds are basically set by the position of the escapement assembly which is attached to the shutter bottom plate via oversized holes. Depending on the place you push it, slow speeds are affected more than higher speeds or vice-versa. Sometimes it is not easy to find proper position so that all speeds run properly. Maybe it was adjusted in a somewhat critical position before and due to minor wear the 1/10 adjustment is slightly off mechanically - which can have major effect on this speed setting.
BTW on late Prontor SVS shutters there was an additional escapement stage active at 1/15 only, so adjustment of the cam was less critical. |
Ed
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 02:20 pm: |
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1/15 sec is one the key adjusting points in the compur. Get 1 sec close and adj. 1/15 by carefully (usually only takes a little--you don't want to break off the pin) bending the pin that rides to speed ring. Outward decreases the speed, in mskes it faster. Unless you got a good ear, yoiu need a speed tester. |
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