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Contax 2a shutter testing
Old 02-15-2018   #1
richardHaw
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Contax 2a shutter testing

Hello. This might sound silly but i am not sure if testing a contax 2/3a shutter requires me to read the opening and closing curtain speeds. I was testing my contax for several nights now and while my tester gave me radically unusable readings, they seemed OK to me so far. No bounce, etc.

How many springs does this thing have? Last time i checked, there is only one at the bottom. Thanks, hoping somebody can answer this.
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Old 02-15-2018   #2
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The springs for the two curtains are on a common shaft. This makes adjusting shutter speeds on this camera quite difficult. You need to set a tension, let it equilabrate for a few days, and then add another notch to the tension. So, it takes a couple of weeks to get the shutter speed adjusted. Merely adding tension won't make the shutter go faster. The net shutter speed may even be slower depending on which curtain starts to go faster first.

Also, if the ribbons and gear train are not clean and unfrayed, you won't get consistent speeds.
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Old 02-15-2018   #3
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Quote:
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The springs for the two curtains are on a common shaft. This makes adjusting shutter speeds on this camera quite difficult. You need to set a tension, let it equilabrate for a few days, and then add another notch to the tension. So, it takes a couple of weeks to get the shutter speed adjusted. Merely adding tension won't make the shutter go faster. The net shutter speed may even be slower depending on which curtain starts to go faster first.

Also, if the ribbons and gear train are not clean and unfrayed, you won't get consistent speeds.
I got that covered. i am now getting correct speeds with the minimum of tension just +2 or 3 clicks when using a single center shutter tester.

I get weird values when I am using a tester with 2 sensors, though. that's the mysterious thing.

ah, OK. so both springs are on the bottom drum...thanks, that clarified a lot of things. I have a German manual and the parts map is all in German, it was of limited help to me.
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Old 02-16-2018   #4
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I got that covered. i am now getting correct speeds with the minimum of tension just +2 or 3 clicks when using a single center shutter tester.
This is it. I have serviced many of them. The trick is, given that everything is well set at the cams and shafts located under the top cover, and that the narrow black ribbons are not frayed, that the shutter cords are safe and sound, and that everything mechanical is clean and lubed as it should (typical amounts of the proper oil where it's necessary), and given that you have a camera with no corrosion in the first curtain shaft housing nor on the beveled gear trains, to adjust the tension so that 1/25 is both accurate and the most silent which you can get when 1/500 and 1/1250 are both working (shutter not running closed). If the shutter begins to emit a loud whack at 1/25, you have tensioned too much. With a film in the camera, 1/25 should be almost inaudible.
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Old 02-16-2018   #5
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This is it. I have serviced many of them. The trick is, given that everything is well set at the cams and shafts located under the top cover, and that the narrow black ribbons are not frayed, that the shutter cords are safe and sound, and that everything mechanical is clean and lubed as it should (typical amounts of the proper oil where it's necessary), and given that you have a camera with no corrosion in the first curtain shaft housing nor on the beveled gear trains, to adjust the tension so that 1/25 is both accurate and the most silent which you can get when 1/500 and 1/1250 are both working (shutter not running closed). If the shutter begins to emit a loud whack at 1/25, you have tensioned too much. With a film in the camera, 1/25 should be almost inaudible.

Thanks. i am worried about fading

the results with a 2-sensor tester doesn't makes sense but it all looks good with a 1-sensor tester. weird.
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Old 02-17-2018   #6
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The good news is, the shutters are traveling roughly at the same speed for the higher speeds but they are not synced very well at lower speeds. As much as 20%. I hope this won’t cause fading or whatever.
Here’s what i got so far:

1s: 1.2s

2s: 3s

10s: 8s

25s: 23s

50s: 40s

100s: 105s

250s: 260s

500s: 490s

1250s: 1050s

Not perfect but pretty close. A good cleaning and oiling all 3 springs did the trick amazing what oil and plenty of tissue and effort can do

Installing the lower drum was the most important part of the job. You just can’t install it just like that, it had to be spooled a bit so the tension is right then add more tension to taste.

1/25s isn’t totally silent but it doesn’t ping, just the clack so I guess it’s ok.

I hate to open this again after a test roll. Do you think i will get some fading with this? Uneven exposure is what i am referring.

By the way I had to tune the slow and fast speeds cam.
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Last edited by richardHaw : 02-20-2018 at 16:48. Reason: typo, should be 1/8s
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Old 02-18-2018   #7
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after a test roll:

NO fading so I assume that it's OK

all speeds working roughly consistent with a small amount of differences mostly apparent at the higher speeds from 250s and up.

50s works as 38s unfortunately. the most important thing to me is 100s is working as 99.5s, this speed is the most important to me.

light meter was is now a bit more responsive but still inaccurate.

shutter is noisier than leica style shutters. it's noisy but I tested another one at a shop and mine is a tad quieter so I am not complaining. it does sound louder now that the shutter is enclosed inside the camera. I suspect that this is due to the other spring-loaded parts. being a vertical-travel shutter is also a likely cause.

so far so good. going to observe this more.
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Old 02-18-2018   #8
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This is it. I have serviced many of them.
Really? The world really could use some people that can overhaul these excellent cameras.
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Old 02-18-2018   #9
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You got the faster speeds as accurate as possible, which is great.
1/1250 is never that fast. So, getting 1/1000 out of it is fantastic.
On the Kiev 4, they finally admitted that the top speed was 1/1000 and marked it as such.

I wonder about the slower speeds. 1/10 is almost 1 stop off at 1/18.
Is there a slow speed gear train that somehow must be adjusted?

Otherwise, just know what the speeds are, and use them as per your hand held meter.
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Old 02-18-2018   #10
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there are 2 cams that can be adjusted for this. a high speed cam and a low speed cam. i have spent too much time working on this and I don't want to spend more time with this camera so I just let that be.

i also noticed that the black dial ones were almost half as silent

to be honest, i think I may have tension this too much. i was expecting a silent and refined "fwip" but I ended up with a "clack". again, the shutter sounds quiet enough when unmounted but it got louder once I had it inside the camera body and sealed everything.

at this moment, i am just happy that this is now all done so I can go back to the pre-war contax 2 and finally go back to servicing the Nikon F cameras as soon as that is over. man, i miss working on Nikon cameras.

Sorry, Robert that was a typo. it's supposed to be 1/8s which I can live with. the only thing that bothers me is 1/50s which acts like 1/38s so I am missing 1/50s which is also important to me but not as important as 1/100s which I use almost all the time. apologies for the confusion.
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Old 02-19-2018   #11
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Quote:
Originally Posted by Hatchetman
Really? The world really could use some people that can overhaul these excellent cameras.
Really yes, but I did this in the very early 2000s as an amateur job. Now I wouldn't have some time free enough to tackle any. I've kept one "black dial" IIa body for me, but don't have the time to use it, unfortunately (it seems to still work properly in spite of that risky lack of exercise).

Anyway what I did can be done by others, you just have to be very patient and to work after all the good instructions about them which you can find around.

Given that you tackle one which won't deny the overhaul (damaged by a previous repair attempt, ribbons or shutter cords problems, corrosion where it is critical, shutter which will always run closed at high speeds after a few days spent on a shelf in spite of all your efforts including some ultrasonic cleaning of all the hidden shafts, etc).

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Originally Posted by richardHaw View Post
light meter was is now a bit more responsive but still inaccurate.
There is no meter on a Contax 2a (IIa actually). What camera are you working on

A "color dial" 3a (IIIa) I guess.
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Old 02-19-2018   #12
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Quote:
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Really yes, but I did this in the very early 2000s as an amateur job. Now I wouldn't have some time free enough to tackle any. I've kept one "black dial" IIa body for me, but don't have the time to use it, unfortunately (it seems to still work properly in spite of that risky lack of exercise).

Anyway what I did can be done by others, you just have to be very patient and to work after all the good instructions about them which you can find around.

Given that you tackle one which won't deny the overhaul (damaged by a previous repair attempt, ribbons or shutter cords problems, corrosion where it is critical, shutter which will always run closed at high speeds after a few days spent on a shelf in spite of all your efforts including some ultrasonic cleaning of all the hidden shafts, etc).



There is no meter on a Contax 2a (IIa actually). What camera are you working on

A "color dial" 3a (IIIa) I guess.
yes, sir. it's a IIIa

I am going to write an overhaul article on this, please feel free to correct me if I wrote anything wrong

now looking for a nice IIa black dial. the color dial ones are noisier than my Nikon S with titanium shutters
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Old 02-21-2018   #13
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just got a Contax 2a (BD) at the camera bazaar

the black dialed ones are noticeably quieter than the color dial models. no "clacking" and sounds more akin to pre-war Contax shutters. I also notice that they are also much smoother to wind. all of the color dial models i have tried were louder
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Old 03-01-2018   #14
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https://www.youtube.com/watch?v=5Yqoxe84eIE&t=1135s

here's a video that I did last night

mr Highway61 (I forgot your name!) was pretty helpful along with the rest of the people here. The funny thing is I am more comfortable working with the Contax 2a/3a than the pre-war ones. the mechanism is easier for me to understand.

everything happens right before your eyes and is not as friction-dependent as the earlier design.
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Old 03-02-2018   #15
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Quote:
Originally Posted by richardHaw View Post
https://www.youtube.com/watch?v=5Yqoxe84eIE&t=1135s

here's a video that I did last night

mr Highway61 (I forgot your name!) was pretty helpful along with the rest of the people here. The funny thing is I am more comfortable working with the Contax 2a/3a than the pre-war ones. the mechanism is easier for me to understand.

everything happens right before your eyes and is not as friction-dependent as the earlier design.
Hi Richard, itís very interesting looking inside a contax iia, Iíve changed many Kievís and contax ii shutter ribbons but never opened up a contax iia before. I always assumed it would be too complicated to understand!

Regards,
Nathan
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Old 03-02-2018   #16
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everything happens right before your eyes and is not as friction-dependent as the earlier design.
I beg to differ. On the postwar shutter the coupled beveled perpendicular gears unit driving the shutter curtains shafts are extremely friction dependent. The least hesitation of the mechanism here when the shutter button is depressed will make the shutter travel closed at high speeds. Plus, the selftimer design is the dumbest ever and will make the shutter travel closed at pretty all speeds above 1/50s in case of the slightest parts machining or adjustment error. The postwar shutter will also have problems in case of some slight corrosion of some hidden shafts which you won't be able to reach in order to clean and lubricate them, because they are sealed.

The wheezy prewar shutter suffers from the well documented ribbons and leather cords problems but is otherwise really more reliable.

I still own a Contax IIa which I like very much. So far it works well. But I also have another one taken apart in a box, which drove me nuts (worked immediatly after the full service, which included some ultrasonic cleaning of everything which had to be, then stopped working after some days spent on the shelf and so on). Both are "black dial" models. The "color dial" model which I also had never wanted to work (infamous shutter release problem).
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Old 03-03-2018   #17
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I beg to differ. On the postwar shutter the coupled beveled perpendicular gears unit driving the shutter curtains shafts are extremely friction dependent. The least hesitation of the mechanism here when the shutter button is depressed will make the shutter travel closed at high speeds. Plus, the selftimer design is the dumbest ever and will make the shutter travel closed at pretty all speeds above 1/50s in case of the slightest parts machining or adjustment error. The postwar shutter will also have problems in case of some slight corrosion of some hidden shafts which you won't be able to reach in order to clean and lubricate them, because they are sealed.

The wheezy prewar shutter suffers from the well documented ribbons and leather cords problems but is otherwise really more reliable.

I still own a Contax IIa which I like very much. So far it works well. But I also have another one taken apart in a box, which drove me nuts (worked immediatly after the full service, which included some ultrasonic cleaning of everything which had to be, then stopped working after some days spent on the shelf and so on). Both are "black dial" models. The "color dial" model which I also had never wanted to work (infamous shutter release problem).
maybe I am just more comfortable with the 2a shutter design

my Contax 2 will only open the 1st curtain when you press it lightly and open the 2nd when you press harder. this forces me to press the button harder. I am thinking that this is due to the lack of friction on the buckles/clutches or probably a spring that wasn't oiled properly I am in the mood for another pre-war Contax, maybe I can get that to work perfectly.
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Old 03-05-2018   #18
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my Contax 2 will only open the 1st curtain when you press it lightly and open the 2nd when you press harder. this forces me to press the button harder.
Sounds like the shutter curtains catch arm may touch the upper curtain so that the upper curtain is not free to move 100% as soon as you depress the shutter release. Remove the shutter cover and look at this arm. Also I would recommend to smoothen the shutter curtains rails inside the shutter cover with ultrafine dark grey abrasive paper designed to be used wet.
The way you tighten the four screws of the shutter cover is also important. You must tighten them all with the same torque, step by step. Too much torque applied first on one screw while the others haven't been tightened yet may cause what you describe.
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