Compur Electronic 3 shutter - what could go wrong?

[Paul Ewins]

I bought a reproduction repair manual from here: http://www.photobooksonline.com/book...ersrepair.html (#8183). It is basically a single speed (1/125) mechanical shutter that has an electronic delay added on to achieve the slower speeds. So 1/60 is 1/125 shutter + 1/115 delay, 1/30 is 1/125 shutter + (1/115 + 1/60) delay and so on (the math makes more sense in decimals than fractions). The speed change is governed by resistance with individual resistors for each speed so that part is repairable.

[Havoc]

It are not the resistors that will have issues but the capacitors. They can turn bad.

[linhofbiker]

My shutter with lens arrived yesterday from the Ebay seller in Wien Austria. The battery container had a spacer that worked with a CR123 3V battery. I put a battery in it but the cover kept popping off, so I found 2 O-rings that hold it in place. The shutter works like a charm. The other lens, a 165 SA, is supposed to arrive today. It has a battery holder, but I think I will use the same modified battery holder with it too. As advised I will keep the battery holder off the lens when not in use. BTW it is nice to have a mechanical speed of 1/125 (or, 1/200?) available when the battery holder is removed.

I hope to mount my 19" f/11 apochromat(red dot)artar in barrel in the first shutter, even though I may loose half a stop or so. The rear element unscrews but the front element will not budge. When I do get it off I am hoping it will fit into the shutter. The front element has 3 set screws just in front of the aperture setting ring and I assume they are preventing the front element removal. Also, the barrel has an opening for some kind of filter and has a lever that will close the opening completely.

[Louis Pacilla]

I hope to mount my 19" f/11 apochromat(red dot)artar in barrel in the first shutter, even though I may loose half a stop or so. The rear element unscrews but the front element will not budge. When I do get it off I am hoping it will fit into the shutter. The front element has 3 set screws just in front of the aperture setting ring and I assume they are preventing the front element removal. Also, the barrel has an opening for some kind of filter and has a lever that will close the opening completely.

I assume you know this is not going to be a direct fit so are you going to cut & machine the threads your own tubes and if not are you sending them to SK Grimes? If your sending them off you may want to send the barrel along with the cells so Adam will know the proper spacing and all. They will return the barrel back once cells are mounted.

[Bob Salomon]

My shutter with lens arrived yesterday from the Ebay seller in Wien Austria. The battery container had a spacer that worked with a CR123 3V battery. I put a battery in it but the cover kept popping off, so I found 2 O-rings that hold it in place. The shutter works like a charm. The other lens, a 165 SA, is supposed to arrive today. It has a battery holder, but I think I will use the same modified battery holder with it too. As advised I will keep the battery holder off the lens when not in use. BTW it is nice to have a mechanical speed of 1/125 (or, 1/200?) available when the battery holder is removed.

I hope to mount my 19" f/11 apochromat(red dot)artar in barrel in the first shutter, even though I may loose half a stop or so. The rear element unscrews but the front element will not budge. When I do get it off I am hoping it will fit into the shutter. The front element has 3 set screws just in front of the aperture setting ring and I assume they are preventing the front element removal. Also, the barrel has an opening for some kind of filter and has a lever that will close the opening completely.

That slot is not for filters. You bought a process lens and they accepted drop in disks to create different dot patterns for the print presses.

[linhofbiker]

That slot is not for filters. You bought a process lens and they accepted drop in disks to create different dot patterns for the print presses.

Thanks Bob. A process lens is designed for closeups. Does the spacing differ when used at infinity. I seem to recall that the spacing on a Componon-S was different than the Symmar-S equivalent, although for most practical purposes it made no difference.

The Compur Electronic 3 has M 58x0.75 front and rear with M 62x0.75 thread for retaining ring. Is this pretty standard? If the barrel elements don't fit then I will have to send it all to SK Grimes.

[Dan Fromm]

A process lens is designed for closeups. Does the spacing differ when used at infinity.

You'll get conflicting answers. The ones I like are that it depends on the lens and that process dialytes (Apo-Artars, dialyte type Apo-Nikkors, Apo-Ronars, Repro-Clarons) are optimized for 1:1 and hold their corrections very well to infinity.

I can't find it but I vivid recall reading a piece of Rodenstock propaganda that insisted Apo-Ronars performed better at infinity than any telephoto lens of the day.

[linhofbiker]

Recently obtained some more:

1) 165mm f/8 Super Angulon in Electronic 3
2) 75mm f/5.6 Super Angulon in Electronic 1
3) 150mm f/5.6 Componon in Electronic 3
4) 210mm f/5.6 Symmar-S in Electronic 3 (inserted my cells)

[Pere Casals]

Recently obtained some more:

Those shutters operate the coil with two voltages. They need a short impulse at high voltage to open at its max rated speed, but this impulse has to be short because that high voltage ¡s around x4 times higher that the one (nominal) it can be resisted by the inner coil in a long period. Then voltage drops to the level that simply holds the shutter open, that it can be 1/2 of the coil nominal voltage.

[linhofbiker]

Those shutters operate the coil with two voltages. They need a short impulse at high voltage to open at its max rated speed, but this impulse has to be short because that high voltage ¡s around x4 times higher that the one (nominal) it can be resisted by the inner coil in a long period. Then voltage drops to the level that simply holds the shutter open, that it can be 1/2 of the coil nominal voltage.

Is this good old 1950's and 1960's technology? All 4 examples I have run without battery at the max mechanical speed. Using a 4.5 volt battery all speeds function as intended. My original post was about "what could go wrong" in anticipation of trouble. I have the Compur manual of how to service these shutters, but so far all are working fine. As was suggested I keep the battery container off the lens until it is needed. I have two good battery containers and one that needs work, but I only need one since I only use one lens art a time.

The Compur repair manual shows what should be lubricated and what "grease/oil" should be used - supplied by Compur themselves. Does anyone know what type of "grease/oil" was specified and what modern substitute should be used instead. As a precaution I would like to lubricate all shutters since I don't know their history. Or is this playing with fire?