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Mareklew
Tinkerer
Username: Mareklew
Post Number: 2
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 23, 2010 - 04:44 am: | 
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I have a question to the more experienced camera fans 
Shutter in my Yashica runs dead-on for times 1s - 1/60s. But anything faster is off:
1/125s is 1/90s in reality.
1/250s is 1/160s,
and 1/500 clocks in at 1/220s.
I don't really expect 1/500 to be anywhere near reality, but I'd like to have 1/125s where it belongs. I don't know however, if it's realistic - how do other shutters of this type perform.
I have till now
1) taken the shutter out of my camera,
2) removed the faceplate and speed selection cam from its front,
3) removed the self-timer assembly (plastic gears)
4) dunked the rest in white gas = coleman fuel = lighter fluid = light, easily flammable, volatile liquid with a sharp, but not repulsing smell that dissolves oils well ;). Put it in a small ultrasonic cleaner and let it run for a few minutes to remove light contamination.
6) Tested the shutter: all times went for the worse, 1/125s sitting at 12.5ms = 1/80s.
5) dunked it in clean petroleum (paraffine oil, lamp oil, oily feeling liquid with a heavy smell, dissolving gunk well, leaving oily residue), again ultrasonic cleaner. Some more dirt was dislocated, but nothing to write home about. Repeated washing in white gas to remove excess of petroleum.
6) Reassembled. Nothing changed really, shutter times are just a tad bit better, but still off (1/125s was at 1/85s before cleaning).
On http://pheugo.com/cameras/index.php?page=copalmxv there's a photo of a similar shutter:
http://img405.imageshack.us/img405/8024/shut04.jpg
This is a closeup of the retarder. The whole assembly can pivot around the left flat-head screw in the uppermost plate (the topmost plate has two screws and three bushings between them. The right screw has a feather holding escapement. I mean the other screw). The assy is held by a second small screw with a philips head, not present in the photo mentioned above. By releasing a bit of tension on that small screw I can pivot the retarder assy a bit and slightly influence the shutter speed, but only towards slower (i.e. turn my 1/90s into 1/80s).
I my shutter the left screw has a philips head too. I have unfortunately stripped the head in an attempt to remove the assembly *shame on me*.
What are my options, besides accepting it and using 1/250s setting as 125?
thanks in advance,
Marek Lewandowski |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 224
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 23, 2010 - 10:34 am: |
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Without having specific knowledge of this particular shutter, but having experience with other similar leaf shutters, I'd guess that the next step would be more complete disassembly and cleaning, which is usually the ticket to a well-functioning shutter. (Meaning removal of shutter blades and the shutter operating ring.) Probably there's still some gunk somewhere inside that mechanism that wasn't flushed out. It doesn't take much of a slightly sticky substance to slow down a shutter substantially. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 5
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 23, 2010 - 12:24 pm: |
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Thanks for your response David!
I hope maybe somebody who has had this particular shutter in his/her hands will still chime in, as
on the way to further disassembly I have the stripped screw head problem: I can't really get it out. I'd love to know, how it MEANT to be adjusted in the first place, and if this particular screw has any 'trick' to it.
Meanwhile I took this camera to work, where I have access to an oscilloscope and actually looked at the photodiode response and it seems, that it's not as bad as I thought. Taking the opening-closing time into consideration the 1/125th varies from 1/120th at f:3.5 to about 1/90th at f:11. Still a tad slower, than it should be, but not as dramatic, as it felt before. The blade opening and closing times are about 1.5-2ms resulting in an effective 1/300s at 1/500s setting.
Thank you for any help you can provide!
Marek Lewandowski |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 8
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 24, 2010 - 07:02 am: |
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I thought I posted an update yesterday, but it must got eaten ;)
I have managed to get the stripped screw out, disassemble the shutter, wash it thoroughly in white spirit and reassemble (albeit not without a moment of great confusion, as mentioned in another thread). It did not seem to improve anything in the shutter's operation though.
Is there anything I can do still? Lubricate? I read these are meant to run dry, but...?
TIA
Marek |
Paul_ron
Tinkerer
Username: Paul_ron
Post Number: 207
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 24, 2010 - 07:43 am: |
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THis site has many threads on repairning your camera as well as shutter accuracy issues. Read some of the postings n see if you can find a remidy here....
http://nelsonfoto.com/SMF/index.php?PHPSESSID=f1l8pcq30r7ap2qkcl2f455df3&board=3 6.0
BTW this site is well worth joining if you are tecnically capable. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 9
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 25, 2010 - 04:21 am: |
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Thanks Paul, that site is interesting indeed!
Anyway, I found out, that after drying, my shutter now is even SLOWER than it was.
I have taken it completely apart and washed in white spirit. I wonder, shall any lubrication be necessary?
Marek |
Nickon51
Tinkerer
Username: Nickon51
Post Number: 126
Registered: 05-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 25, 2010 - 08:08 am: |
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I wonder what you are referring to as "white spirits". Ronsonal or lighter fluid is about the best to use on shutters. IMHO you do have to lube shutters sparingly at the right places. If it slides, use grease, if it rotates use clock oil. The blades must be absolutely clean and dry and oil free.
The retard mechanism is timed by the lever that is moved in and out as the speed ring rotates. You can see that by placing the ring back on and changing speeds. Adjust by moveing the retard assy in or outwards, which changes the time that the retard unit is in action.
If you still cant get it fast enough then you may have to work with just the shutter without the retard. Try and figure out what speed that would be and work on cleaning and lubing the shutter and or adjusting the spring tension until is it around right. Then put the retard mechanism back in and see what happens.
If you really want to do it right you should dismantle the gears from the retard unit, clean the pivots and holes with a toothpick. Reassemble it and put a very small drop of clock oil in the pivot hole oils sinks. Don't lube the gear teeth, but a smear of oil on the pallets. Not many go that far, but its the way it should be done. |
Paul_ron
Tinkerer
Username: Paul_ron
Post Number: 208
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 25, 2010 - 01:21 pm: |
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Yes shutters do get lubed with a very light watch oil or from your music store, get brass instrumnet valve oil. As stated above, if it slips it gets greased, if it turns it gets oiled.
Did you register on the site? Present your problem there and you'll see many retired camera repairmen come to the surface like moths to the light.
OH and if you liked that site.. check this one out when you're done playing with the camera n need a break?....
http://www.cheeseandburger.com/
. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 11
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 25, 2010 - 02:48 pm: |
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You know, guys, I just experienced The Forum Syndrome. This means: once you arrive at a solution, you log onto the forum and find out, the last guy posted exactly that :P...
Anyway, thank you all, because I just wanted to ask, how bad it is to actually lube it
This is what I did after my last post and before reading Nickon and Paul's posts:
- I disassembled the whole thing once again, because I found there's still something wrong with the aperture (there was: a piece of hair got into it).
- Since it was in pieces anyway, I dunked it into GRCL *) filled ultrasonic bath (i know it's not ok to use flammables in ultrasonic baths).
- Reassembling, this time in rubber gloves and a head cap (hair), taking extreme care not to introduce ANYTHING foreign into the shutter, I thought: don't troubleshoot system, troubleshoot components. So I assembled just the shutter blades into the main body.
- I run this part only, dry, several times, clocking about 1/300 - 1/500s, depending, what you take as reference point. Thus I assumed no gunk/oil/whatever is present or needed in this part. This left the retarder.
- Since retarder can be easily removed and washed, I decided to go ahead and use some fine oil on it. The lightest thing I found in the household was German synthetic "light gun oil" (resin and acid free, as advertised). I applied tiny amount using a needlepoint onto each bushing. I also smeared a little where the two hooks hit: the one of retarder and the one driven by main spring.
- The shutter clocked dead on.
I will check in a month or so, if the oil I used slows things down, if yes, I will re-wash the retarder again and use some better oil. I have used this oil already on fine mechanics and it didn't seem to thicken over time, but this case may be more critical.
Paul: I have registered, but they hand-activate accounts, so I still await the activation email.
Now I'm ready to tackle problem #2: squeaky film advance. I can almost feel the pain of gears rubbing dry... I never heard a camera run so squeaky before (yes, I had a Yashica already... ;P)
Guys, thank you a lot: for advice, for help, and for reassuring when I was working faster than you typed, that what I did made sense. I can go to sleep happy tonight, thanks to you all.
I also now have a much better understanding of how this thing work. From a bunch of confusing springs and gears it transformed over the past few days into an ingeniously simple piece of mechanics that just logically belongs together
Marek
*) GRCL = Generally Recommended Cleaning Liquid. Depending where you live it's called Lighter fluid, Ronsonol, Waschbenzin, I've read it referred to white gas or white spirit too, nut sure if properly. Light, not aggressive solvent, very volatile fraction of crude oil, boiling about 50°C, flammable and explosive as vapor. Enhanced with explosion retarding additives it is gasoline. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 229
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 25, 2010 - 07:33 pm: |
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Thanks for the exhaustive description.
Moral of the story here: yes, Virginia, shutters sometimes do need lubrication (but not very much!) in addition to wanting to be very, very clean.
There is one exception to the "no lube on shutter blades" that I like to use: graphite. No, don't sprinkle powdered graphite on them (and please don't ask me how I know that this results in a nice dusting of graphite all over your nice clean lenses). Just take a "lead" pencil (a #2 is nice) and rub it sparingly over the moving parts of the shutter and blades. Doesn't make a dramatic difference, but doesn't hurt, either. |
Paul_ron
Tinkerer
Username: Paul_ron
Post Number: 209
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 25, 2010 - 08:35 pm: |
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Good tip.
Actually I had a stuborn shutter once. I rubbed a #2 pencil on paper n got the graphite on my finger n wiped it over teh blades n it worked fine since. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 14
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 26, 2010 - 03:04 am: |
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During the last reassembly I found out, that the soft rubber "nose" of a rubber blower works very nice to clean the last specks of dust from the shutter leaves. It's very soft, but has such "grabbing" surface, that helps removing any residue from smooth surfaces.
I have managed to silence film transport too, as close listening revealed, squeaky weren't the gears inside, but the stud that pulls the taking roll, it ran dry in the camera wall hole, having worked all its grease outside. I put a smear of fresh grease with a q-tip and now it winds with a quiet whirr.
I can't rest just yet, however, as I found the light meter to be largely off. As I count to the few lucky, who still are in possession of an actual mercury battery, I have checked it with this battery and it's still off, by more than two stops. All mechanical linkages seem OK, so I wonder, how to adjust it...
Thanks, guys!
Marek |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1075
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 26, 2010 - 04:27 pm: |
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In skimming over the above discussion, I see a lot about the shutter but not much about how you know that it is running, for example at 1/220 at the 1/500 setting. How are you testing the shutter?
The reason that I ask is that a leaf shutter is never intended to be open for only 1/500 second at the 1/500 second setting. Because of the way the leaves open from the center to the edge and then reverse, in order for the shutter to pass the light equivalent of 1/500 second, the center has to be open much longer than that while the blades are still obstructing most of the outer area of the lens. The outer edge is cleared for only an infinitesimal moment as the blades reverse direction. So if, for example, you are testing with a digital shutter tester with the sensor in the center of the lens, 1/220 second might actually be perfectly in spec for the 1/500 speed.
At slower speeds this still happens but it is an unmeasurably small effect in relation to the longer time that the blades are held fully open.
Another effect of this behavior is that the effective shutter speed at the fast end varies as a function of aperture selected: at f/3.5 you do get an accurate 1/500 equivalent, but at f/22 the entire working aperture is exposed for the whole 1/220. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 18
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 26, 2010 - 07:28 pm: |
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Hi Rick,
I used three methods to check the shutter speed, varying in precision and complexity. I used a photodiode as sensor in each case:
1) for what I would call an accurate reading I would connect a digital oscilloscope to the photodiode output, install the diode on the assembled camera's film plane, illuminate it through the assembled lens and observe the produced waveform. Since in an assembled objective lens the shutter is where the diaphragm sits, its opening and closing affects light intensity, but does not cast sharp shadow on film plane. Using scope cursors I'd take a reading between about middle of the rising slope to about middle of the falling slope, thus approximating area-under-the-curve. For 1/500s one could clearly see, that the blades never stop: light intensity would rise to peak and then immediately start dropping again. At 1/500s shutter would run at effective 1/220s, i.e. film plane illumination would rise approximately linearly over 4ms and fall, also about in a linear fashion, for about 5ms, totaling 9ms open-time =1/110s, but since the waveform is triangular, its effectively 1/220s.
2) Since I have a scope at work, but don't own a digital one myself, I'd do the #1 check only once a day, to verify my tinkering results, and at home use the photodiode+sound recording on a PC method. This does not show slopes so clearly, but is pretty close on speeds in the range of 1/125s and slower.
2a) For assembled lens I'd just test it as with a scope.
2b) For testing shutter alone, I'd take a diffuse (area) light source, so that photosensor would see more and more light while the shutter is opening and then less and less while it's closing, so I can still see the opening/closing time, its no longer photometrically accurate though.
For the reason you stated, I'd measure fast shutter speeds with aperture wide open. I'd love to be able to adjust the shutter to clock 1/125s at f:8, as it is about the combination I use most often, but I believe it's not what the designers had in mind.
Greets,
Marek |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1076
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 27, 2010 - 08:40 pm: |
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It does sound like you've taken the leaf shutter's quirks into consideration and you actually have a slow shutter. Not sure why that would be. As you have observed, there is no delay at 1/500, it opens and closes just as fast as the main spring can pull it. Generally the same is also the case at 1/250, the difference being a booster spring that is engaged at 1/500 to increase the velocity of the blades - so at 1/250 you should see an identical constantly-changing curve on the oscilloscope, but with a longer slope.
Since there is no delay mechanism of any kind engaged at these speeds, the only thing I can think of that would cause them to run slow is either a weak spring or an unusual amount of friction dragging against it.
Beginning at 1/125 and from there down, the curve should have the same ascending and descending slope as the 1/250 setting, but with a flat top where the blades are held fully open by the delay escapement. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 21
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 29, 2010 - 06:25 am: |
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Rick, I'm not sure if you are right about this particular shutter. It does not seem to have a booster spring, or I can't see how it would be activated. The main setting cam interacts with only 4 pegs:
Peg #1 locks the "B" lever, its cam has only one dent (B).
Peg #2 locks the escapement of the retarder, it is active for faster speeds (1/60 ... 1/500).
Peg #3 switches gearsets in retarder between slow speeds (1, 1/2, 1/4) and medium/fast speeds (1/8, 1/15, 1/30 with escapement interaction and 1/60 .. 1/500 with escapement lock)
Peg #4 adjusts the length of retarder "hook" travel, before it allows shutter to close. In each speed group it has 3 settings, in the fastest group there's a fourth setting for this peg, which removes the retarder hook completely out of the shutter's way for the 1/500th speed. But it acts only on the retarder, as far as I could see.
If one takes the cocking lever as reference, then looking at the faceplate the mentioned hooks are counted counter-clockwise: #1, #2, #3, #4. Between #1 and #2 there's the self-timer assy.
#1 is in the cock/release section, the others belong to the retarder.
BTW: my shutter is working now, or at least I believe so, but I find it important to discuss this topic to concentrate information on this type of shutters in a single thread.
Greets,
Marek |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1080
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 30, 2010 - 10:03 pm: |
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I'm not sure if your shutter would have a booster spring either - it's what Compur used when the Compur (1/250-1/300 top speed) became the Compur Rapid (1/500 top speed), I can't say that everybody did it the same way. Where it's used, generally it's a heavy gauge, small diameter coil torsion spring that gets pushed by one of the cam slots on the SS dial as it goes from the 250 to the 500 setting. Here's a picture of it in a Compur: http://rick_oleson.tripod.com/28c-compur.jpg
In your shutter it may be that the main spring is stronger, so that there is some retard at 1/250 and no boost is needed at 1/500. |
Wonloo
Tinkerer
Username: Wonloo
Post Number: 7
Registered: 07-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 16, 2010 - 07:17 pm: |
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Hi, all.
I found a Knoi-Omega Rapid with a good price. The leaf shutter had some old on it so I cleaned it with lighter fuel and the shutter started to move freely. I noticed the 1 second was about 1 and half second. I adjusted the escapement so 1 second was about on but then the highest speed of low range (1/8) became much faster than the lowest speed of high range (1/15). If I move the 1 second back to 1 and 1/2 then the 1/8 is almost the same as 1/15 if not faster. I notice this also happens on another leaf shutter camera. Did I miss anything? Please help. Thanks.. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 214
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 19, 2010 - 01:38 am: |
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Yes, you missed cleaning the whole thing properly.
Also, don't try to get the speeds 'in sequence', rather get them in order. You don't even know, if 1/8 is running fast, or 1/15 - slow. I would tend to suspect the latter. Oil on the blades came from somewhere, and as oil isn't intelligent being it didn't go only to the blades, but everywhere else. I suspect somebody 'oiled' a slow shutter at some point. Before you start fooling with adjustments, make sure the shutter is properly cleaned and then see, if adjustments were necessary.
Marek |
Wonloo
Tinkerer
Username: Wonloo
Post Number: 8
Registered: 07-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 19, 2010 - 11:29 am: |
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Thanks Marek, You are one of the knowledgeable persons that I was hoping will help.
The escapement and the blade under it had the most of the old oil stains. I took out the escapement and gave it and all blades a lighter fuel bath. But when I put the escapement back, I notice the 1/8 and 1/15 are way off. The 1/8 was like free running at 1/125 or faster. That was why I wondered did I miss the gear change between ranges.
One other question, I am not sure I understand the difference between "in sequence" and "in order". Let me ask this way: If I can find the equipment and adjust the timing. Do I want to keep the absolute time for most of the stops but some slower stops are faster than the faster stop or every stop is off but slower one is always slower.
I am trying to make a speed tester from an old mouse. There are also some reading needed on how to interpret the reading of leaf shutter testing. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 215
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 19, 2010 - 04:29 pm: |
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It's very late now here where I live, so i will be very brief, I'll try to elaborate more tomorrow.
The attempt to make shutter speeds appear in sequence (as: next one faster than the previous) is futile if you didn't get them 'in order' first (i.e. 1s is 1second, 1/8th is 1/8th). There are few tricks and dependencies, but it's too much writing for today. Wait till tomorrow
Marek |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 216
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, December 20, 2010 - 03:15 pm: |
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It's again late, but I promised ;)
The speeds are set up by varying the distance traveled by a pawl. The steps are cut into the cam, so you can't change them. Step 1 is 2x as long as step 2, and 4x as long as step three. Then the geartrain changes and you get another three steps, again 1x, 2x and 4x, and so on.
This can work only, if gears in 1st mesh turn 8x slower than gears in 2nd mesh and 64x slower than gears in 3rd mesh.
Since 2nd and 3rd mesh is only friction-limited, the escapement running in 1st mesh is somewhat friction dependent, and on top of that a large part of the faster shutter times is shutter opening&closing time that's only friction, if your friction isn't right, nothing is going to be right and you won't fix it by adjusting the steps or the escapement.
As long, as the shutter is dirty, it will never run good. Trying to adjust the speeds to get in sequence when the slower speeds are too slow or too fast won't work.
A simple test is checking the longest times in each run: 1s, 1/8s, 1/60s and 1/500s. If 1/500s at f:3.5 clocks slower than *effective* 1/300s (consider opening and closing time!), the shutter activator ring is dirty, the main spring is weak, or the mechanics is worn and you won't get it to clock in on 1/250-1/125 anywhere close to what they should be.
(1/60s), (1/8s) and 1s should fall in 1:8:64 ratio. If they don't, clean the escapement properly.
Marek |
Wonloo
Tinkerer
Username: Wonloo
Post Number: 10
Registered: 07-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 21, 2010 - 06:07 pm: |
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I thought I posted this already.
Anyway, you are right. I cleaned the shutter again and still more oil and dust came out. It seems to be in sequence, one is faster then the other. Now, I need a tester to make them in order.
I also have another question regarding a Zebra Tessar name ring removal. Can I ask you in the other thread? |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 217
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 23, 2010 - 01:44 am: |
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Hi,
there are other guys who know more here too - just ask.
I'm off for two weeks of holiday now, with intermittent returns, but i'm going to be offline for some time.
Greets,
Marek |
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