Discovering Compur shutters

[pchaplo]

I’m intrigued by shutters and am reading about Compur shutters. They sounds like masterpieces of engineering. Here are some of the many questions before I buy a lens wth one:
1. Are Compur shutters more accurate than Copal?
2. I can’t see speed makings on some. What is the typical speed range?
3. Of the more recent ones, is there a preferred model or version to look for, for daily use?
4. I see a lens in Compur for sale and seller says it’s hard to change setting to highest speeds. Is this normal or indicative of a problem?
5. With Compur, is it best to change shutter speed BEFORE cocking the shutter?

Other interesting Compur facts, stories, and lessons learned welcome! I love seeing the classic Linhof lenses in Compur shutters. Beautiful objects!

[Corran]

1. It depends on the condition of the shutter. Copals are probably newer and therefore more likely to be in good shape. Generally, I find it much more likely that a Compur shutter needs servicing than a Copal, when buying a used lens w/o prior testing.
2. Depends on the size but more or less the same - though many Compurs, especially older ones, have speeds like 1/5, 1/10, 1/25, 1/50, 1/100, etc., instead of the 1/4, 1/8, 1/15, 1/30, etc. on the Copals.
3. ?
4. Yes it's normal as it is engaging an additional (or different? can't remember) spring
5. Don't think it matters but others may disagree on "best practice."

I'll let others correct me or add to it, but I think I have most of that correct. I have lots of Compurs, some Linhof-brand, in various sizes. One thing about Compurs is they usually have rounder aperture diaphragms at most stops so OOF highlights render less straight and perhaps overall more smoothly. I prefer the Copal accuracy in general - I don't think I've ever had a used Copal come to me significantly off. Have serviced a number of Compurs and have a number needing it now...but that's just my sample size of probably about 50 lenses.

I don't bend over backward to swap lenses from Copal to Compur or vise-versa but they are nice shutters.

[LabRat]

First, I assume you are referring to the later Syncro-Compur shutters, and not the earlier Compur's...

The Syncro-Compurs are well engineered shutters, built with tolerances inside almost like a watch...That said, the downside is that if they didn't have a full, careful CLA by a good tech, those tight tolerances can get rather sticky and bind easily, even just by lack of use... (Ask a Hassy owner who didn't use their shuttered lens for a couple of years about it...) Sometimes they don't like the cold, or adverse conditions... They need a really good CLA, careful operation, and some exercise at least every month or two to be happy (but sometimes fussy)...

Copals have less tight tolerances, but that allows them to continue working well even if not in perfect CLA'd condition, and are slightly newer and a little simpler inside, so a little more tech friendly...

Old Compurs can work OK if serviced, but the iris usually has a lot of slop between the blades, paper, and VERY hard to reinstall!!! Don't get them wet or oily!!! But they usually don't have minimal modern features like sync, press focus opening, have to be un-cocked to operate B & T, etc... (Use 'em if you got 'em, but from another time...)

But they all work, but hard to say what's best...

Steve K

[Pere Casals]

I’m intrigued by shutters and am reading about Compur shutters. They sounds like masterpieces of engineering. Here are some of the many questions before I buy a lens wth one:
Are Compur shutters more accurate than Copal?

Compurs are very good.

No mechanical shutter has to be accurate, most were sold with a +/-30% precission in the specs, so marked 1/30 can be in fact 1/20 or 1/40 and still working as specs says.

...but most shutters are very repetitive, so if precision is important (for slides...) then one should take a shutter tester (from $15 to $100) and measure the actual speeds of the shutter and use it acordingly, if for 1/250 you have 1/190 then stop diafragm what it compensates the missmatch...

If some speeds of your shutter are not repetitive then you may have a problem when using those speeds...

What is crazy in saying that using TXP at ISO 200 makes wonders and not checking shutters' speeds. Exposure have certain tolerance depending on film, at the end metering also is opinable, for example meters have more or less spectral sensitivity to green or blue, an the effect of filtering depends on subject color. But some films like Velvia or CMS 20 have to be nailed, then we have to nail it, for that a shutter tester (and very scientific metering) is what brings on nice consistency.

You may find this reading interesting, I learned from it a lot: http://www.kenrockwell.com/tech/exposure-large-format.htm

[consummate_fritterer]

<snip>

Copals have less tight tolerances, but that allows them to continue working well even if not in perfect CLA'd condition, and are slightly newer and a little simpler inside, so a little more tech friendly...

<snip>

So... Compur vs Copal is analogous to AR-15 vs AK-47. :D

[Bob Salomon]

At least with modern Compur and Copal shutters there are differences that have not been mentioned.
Compur shutters in 0 and 1 sizes have 1/3rd stop click stops and 3 size have ½ stops on the aperture selector lever. Copal has none.
On the back of modern Compur shutters you will find a gear wheel. Compur offered aperture selector sticks that coupled to that gear wheel and attached to the rear of the shutter that allowed the user to set the desired aperture from behind the camera. Some also accepted shutter sticks that could also set the shutter from behind the camera. Copal never offered these features.
The aperture control stick was fairly common but the shutter sticks were mostly on Plaubel supplied lenses.
By modern Compur I mean last few productions.

Both Prontor Werke, manufacturer of both Compur and Prontor and Copal have discontinued mechanical shutters. Prontor a few decades ago. Copal fairly recently.

[Jimi]

Both Prontor Werke, manufacturer of both Compur and Prontor and Copal have discontinued mechanical shutters. Prontor a few decades ago. Copal fairly recently.

So, eventually, we'll all be sporting hats, stopping down our barrel lenses well and sip some tea while the light is doing its thing. ;)

[Bob Salomon]

So, eventually, we'll all be sporting hats, stopping down our barrel lenses well and sip some tea while the light is doing its thing. ;)

Mechanical shutters are discontinued. Electronic shutters like the Rodenstock eShutter are current, but only made in 0 size. Rollei Linear Motor shutters were discontinued when the factory was liquidated but may still be available, they were made in 0 and 1 sizes only.

But working used shutters should be around for quite a while.

[LabRat]

So... Compur vs Copal is analogous to AR-15 vs AK-47. :D

Kinda yea, but you can't bury a Copal in the mud, rinse it off, and keep shooting... ;-)

Funny!!!

Steve K

[consummate_fritterer]

Kinda yea, but you can't bury a Copal in the mud, rinse it off, and keep shooting... ;-)

Funny!!!

Steve K

LOL... yeah, that's right. :D

[pchaplo]

Corral,

Thanks for sharing yiur experience. By the way, I like your eclipse photos especially the closeup of the young couple

You service shutters? Can you tell me more about that?

In that work, do you test shutter speeds? What’s the most accurate shutter you’ve seen?




1. It depends on the condition of the shutter. Copals are probably newer and therefore more likely to be in good shape. Generally, I find it much more likely that a Compur shutter needs servicing than a Copal, when buying a used lens w/o prior testing.
2. Depends on the size but more or less the same - though many Compurs, especially older ones, have speeds like 1/5, 1/10, 1/25, 1/50, 1/100, etc., instead of the 1/4, 1/8, 1/15, 1/30, etc. on the Copals.
3. ?
4. Yes it's normal as it is engaging an additional (or different? can't remember) spring
5. Don't think it matters but others may disagree on "best practice."

I'll let others correct me or add to it, but I think I have most of that correct. I have lots of Compurs, some Linhof-brand, in various sizes. One thing about Compurs is they usually have rounder aperture diaphragms at most stops so OOF highlights render less straight and perhaps overall more smoothly. I prefer the Copal accuracy in general - I don't think I've ever had a used Copal come to me significantly off. Have serviced a number of Compurs and have a number needing it now...but that's just my sample size of probably about 50 lenses.

I don't bend over backward to swap lenses from Copal to Compur or vise-versa but they are nice shutters.

[pchaplo]

Steve, oh okay I now see (after your comments) see that one eBay there are old styles and newer looking ones that say Synchro-Compur often on a Linhof board, but also some Schneider’s. Also I see what seems to be a more contemporary all black small “Compur 0” shutter.

I’m looking at a pic of a Compur that has the cover off; it’s beautiful inside. I see what you mean about the engineering being like a watch!



First, I assume you are referring to the later Syncro-Compur shutters, and not the earlier Compur's...

The Syncro-Compurs are well engineered shutters, built with tolerances inside almost like a watch...That said, the downside is that if they didn't have a full, careful CLA by a good tech, those tight tolerances can get rather sticky and bind easily, even just by lack of use... (Ask a Hassy owner who didn't use their shuttered lens for a couple of years about it...) Sometimes they don't like the cold, or adverse conditions... They need a really good CLA, careful operation, and some exercise at least every month or two to be happy (but sometimes fussy)...

Copals have less tight tolerances, but that allows them to continue working well even if not in perfect CLA'd condition, and are slightly newer and a little simpler inside, so a little more tech friendly...

Old Compurs can work OK if serviced, but the iris usually has a lot of slop between the blades, paper, and VERY hard to reinstall!!! Don't get them wet or oily!!! But they usually don't have minimal modern features like sync, press focus opening, have to be un-cocked to operate B & T, etc... (Use 'em if you got 'em, but from another time...)

But they all work, but hard to say what's best...

Steve K

[pchaplo]

Good points about consistency and testing. Which shutter speed tester do you use? I see there is even a phone app!


Compurs are very good.

No mechanical shutter has to be accurate, most were sold with a +/-30% precission in the specs, so marked 1/30 can be in fact 1/20 or 1/40 and still working as specs says.

...but most shutters are very repetitive, so if precision is important (for slides...) then one should take a shutter tester (from $15 to $100) and measure the actual speeds of the shutter and use it acordingly, if for 1/250 you have 1/190 then stop diafragm what it compensates the missmatch...

If some speeds of your shutter are not repetitive then you may have a problem when using those speeds...

What is crazy in saying that using TXP at ISO 200 makes wonders and not checking shutters' speeds. Exposure have certain tolerance depending on film, at the end metering also is opinable, for example meters have more or less spectral sensitivity to green or blue, an the effect of filtering depends on subject color. But some films like Velvia or CMS 20 have to be nailed, then we have to nail it, for that a shutter tester (and very scientific metering) is what brings on nice consistency.

You may find this reading interesting, I learned from it a lot: http://www.kenrockwell.com/tech/exposure-large-format.htm

[Corran]

My apologies, I didn't word that well. What I meant was that I've had many Compur shutters serviced, at various camera repair shops. Never needed to service a Copal.

[pchaplo]

Hi Bob,

Wow! those are interesting facts of which I was not aware. That’s remarkable that modern Compurs have fractional f/stops. I could have used those control sticks on occasion.

Sad to hear that Copal recently discontinued production.




At least with modern Compur and Copal shutters there are differences that have not been mentioned.
Compur shutters in 0 and 1 sizes have 1/3rd stop click stops and 3 size have ½ stops on the aperture selector lever. Copal has none.
On the back of modern Compur shutters you will find a gear wheel. Compur offered aperture selector sticks that coupled to that gear wheel and attached to the rear of the shutter that allowed the user to set the desired aperture from behind the camera. Some also accepted shutter sticks that could also set the shutter from behind the camera. Copal never offered these features.
The aperture control stick was fairly common but the shutter sticks were mostly on Plaubel supplied lenses.
By modern Compur I mean last few productions.

Both Prontor Werke, manufacturer of both Compur and Prontor and Copal have discontinued mechanical shutters. Prontor a few decades ago. Copal fairly recently.

[pchaplo]

Corran, oh I see. No problem. Who did you use for shutter service?


My apologies, I didn't word that well. What I meant was that I've had many Compur shutters serviced, at various camera repair shops. Never needed to service a Copal.

[pchaplo]

Bob, can you tell me more about the Rollei Linear Motor shutters? How did those work - what provided the power? Will those fit modern LF lens with dimensions that have for Copal 0 and 1?


Mechanical shutters are discontinued. Electronic shutters like the Rodenstock eShutter are current, but only made in 0 size. Rollei Linear Motor shutters were discontinued when the factory was liquidated but may still be available, they were made in 0 and 1 sizes only.

But working used shutters should be around for quite a while.

[pchaplo]

Or an ice block :D ...although I did shoot an assignment in S. Dakota at 17 below.


LOL... yeah, that's right. :D

[Bob Salomon]

Bob, can you tell me more about the Rollei Linear Motor shutters? How did those work - what provided the power? Will those fit modern LF lens with dimensions that have for Copal 0 and 1?

They are powered by a battery, same as the battery for the SLX/6xxx series cameras. The battery fits into the hand controller that is used to control the shutter’s operation and features. Since the shutter was available in 0 and 1 sizes any lens that fits a Copal or Compur 0 or 1 shutter can be fitted to the Rollei. However these shutters have a larger diameter then a 3 size shutter. So there can be problems mounting them to some boards, especially if a recessed board is needed.
On the other hand the eShutter is much smaller in diameter and has no problem handling lenses as short as a 25 or 28mm Rodenstock.

Also, Rollei is gone and so are most parts, so future repairs can be very questionable while the eShutter is a current item.

[Corran]

SK Grimes, Frank Marshman, others that I can't remember I think.


Corran, oh I see. No problem. Who did you use for shutter service?

[Pere Casals]

Good points about consistency and testing. Which shutter speed tester do you use? I see there is even a phone app!

I use this one, $15 at ebay:

173304

It is a bare photocell intended to be connected to PC soundcard, but I connect it to an USB oscilloscope.

There are photocell versions wired to be compatible with smartphones jack sockets, and there are $1 apps for it that also can work with shutter's noise, but with noise it is not accurate and has limitations.

This standalone one is around $75 :

173305

[Jerry Bodine]

...Who did you use for shutter service?

I've always used Flutot's Camera Repair for servicing my Compurs and Synchro-Compurs. Carol is very good and easy to do business with.
http://www.flutotscamerarepair.com/

[pchaplo]

Pere, Thannks. Is a USB oscilloscope a large traditional oscilliscope or is it smaller/affordable?



I use this one, $15 at ebay:

173304

It is a bare photocell intended to be connected to PC soundcard, but I connect it to an USB oscilloscope.

There are photocell versions wired to be compatible with smartphones jack sockets, and there are $1 apps for it that also can work with shutter's noise, but with noise it is not accurate and has limitations.

This standalone one is around $75 :

173305

[Pere Casals]

Pere, Thannks. Is a USB oscilloscope a large traditional oscilliscope or is it smaller/affordable?

I use mostly a Picoscope 2205, Picoscope brand models range from under $100 to $25,000... I've other pro oscilloscopes but for most I use the 2205, it is always in my laptop bag, for my job it's enough as never checking signals with the scope over 20MHz. If the laptop runs on bateries then I avoid gounding issues.

Today you can find new and cheap choices at Ebay, Hantek 6022BE 20MHz Digital Oscilloscope PC Based for $49. Also there are wifi oscilloscopes for smartphone:. 2CH 70MHz Hantek iDSO1070A

A capable standalone oscilloscope can be $350, RIGOL Digital Oscilloscope 70MHz DS1072U 500MSa/s.

Price depends on MHz (bandwith) , number of channels (you need one channel) , brand, software...

For a shutter tester you only need the most basic capability.