Arrow on shutter speed dail Compur 2

[Cor]

Dear all,

I just recieved a pre-war (1937) 165mm f6.8 Schneider Angulon mounted in a Compur shutter (I assume it is a 2 5/2). There is an image here (http://www.skgrimes.com/compur/compurbg/c3.jpg) (left at the top).

I have a question about the shutter speed dial: it has an arrow on it, I assume you should rotate in that direction, but what if you are at 1/2 second, but the light changes and you want to expose more, so 1 sec. is it ok to turn against the arrow to the 1?


Now a bit of a weird part: the front element is "shimmed" with 2 small rings of writing paper. The person I obtained the lens from said that the lens was professionally CLAed.

When I searched the forum I found this thread (http://www.largeformatphotography.info/forum/showthread.php?t=9748), describing the same lens and shutter combination (I first thought it was exactly the same lens but the serial numbers of the lens and shutter are not the same, although they are quite close).

Indeed unscrewing the back element shows that the shutter blades are extremely close to the back glass of the front element, explaining the reason of this very thin shimming.

I wonder what it does to the sharpness of the lens. I ran a quick test (on 8*10, stopped down to f32 it should just cover), and by eye balling the wet negative it looks ok, except a softness at the left part of the image, I think I have not centred the lens properly in my home made lens board.

Is there a kind soul who has a Angulon like mine and could measure the total length of the lens in the shutter? The data on the Schneider web site is not corresponding with mine, but that data is post war, and the elements are probably differently mounted.

Thanks in advance,

Best,

Cor

[Leigh]

All manufactured products have tolerances. Shutters tend to err on the short side, while lenses tend to err on the long side.

Shims are used to adjust the cell spacing as necessary so the lens focuses properly.

- Leigh

[Cor]

All manufactured products have tolerances. Shutters tend to err on the short side, while lenses tend to err on the long side.

Shims are used to adjust the cell spacing as necessary so the lens focuses properly.

- Leigh

I know that, Leigh, i am afraid that does not answer my questions, so I'll try to re-phrase them:

- On a old number 2 Dial Set Compur there is an arrow on the shutter speed dial: is this dial only indicating the speed direction, or is there a mechanical reason to only turn that dial in the direction of the arrow?

- On my new 16.5 cm Angulon (6.8) the front element is shimmed with 2 pieces of writing paper, presumably to clear the glass of that element from the shutter blades. A very similar lens/shutter (http://www.largeformatphotography.info/forum/showthread.php?t=9748) combination was shimmed the same way.

I find it strange why this shim is necessary, and I assume it wasn't needed when they made this lens, but maybe the shutter blades got slightly warped in time ?

So I would very much like to know the exact height of a pre-war 165mm Angulon,

Thanks in advance,

Best,

Cor

[David Lindquist]

Dear all,

I just recieved a pre-war (1937) 165mm f6.8 Schneider Angulon mounted in a Compur shutter (I assume it is a 2 5/2). There is an image here (http://www.skgrimes.com/compur/compurbg/c3.jpg) (left at the top).

I have a question about the shutter speed dial: it has an arrow on it, I assume you should rotate in that direction, but what if you are at 1/2 second, but the light changes and you want to expose more, so 1 sec. is it ok to turn against the arrow to the 1?
(stuff about shims snipped)

Thanks in advance,

Best,

Cor

I have two circa 1930 (based on the serial numbers of the Zeiss lenses mounted in them) dial set Compur shutters. Probably No. 2, body diameter is about 3.1 inches, clear aperture is about 1 ⅜ inch. Both dials have an arrow pointing counter clockwise. Dials can be turned continuously counter clockwise. When turned clockwise, both come up against a stop between one second and the highest shutter speed (1/150 and 1/200 respectively). Using my trusty Calumet shutter speed tester, I tried the three lowest speeds on each, approaching the settings both from clockwise and counterclockwise. Each speed was checked three times and the clockwise/counterclockwise trials were done twice.
For one of the shutters there was no evidence that the direction from which the setting was made made a difference; speeds for 1, ½ and ⅕ seconds were quite consistent (.82-.84, .43-.46 and .20-.22 respectively).
This was not the case for the other shutter. In particular ½ second was .64-.67 when set rotating the dial counterclockwise, and .46-.51 when set by turning the dial clockwise.
So my inclination with my shutters, especially since I can test them for consistency, is to set speeds by always rotating the dial in the same direction, i.e. counterclockwise (even though with the one shutter it didn't seem to matter). Having said that, I don't know what Fredrich Deckel's intention was 80 years ago. Maybe the arrow is just to remind one not to try to turn the dial clockwise between 1 second and the highest shutter speed because if you try hard enough you'll damage something.

hope this helps a little.
David

[BrianShaw]

- On a old number 2 Dial Set Compur there is an arrow on the shutter speed dial: is this dial only indicating the speed direction, or is there a mechanical reason to only turn that dial in the direction of the arrow?


Beneath that shutter speed dial is a cam. A spring-loaded lever for setting the shutter speed rides along that cam. If turned backward, the lever might bend if forced past the "stop" that David describes. That "stop" is where the cam resets to it's lowest position.

If you remove that shutter speed dial (or look at any exploded diagram) you can immediately see why the dial should be turned in only the direction marked by the arrow.

[BrianShaw]

Maybe the arrow is just to remind one not to try to turn the dial clockwise between 1 second and the highest shutter speed because if you try hard enough you'll damage something.


Yes (says the ghost of Herr Deckel).

[David Lindquist]

Beneath that shutter speed dial is a cam. A spring-loaded lever for setting the shutter speed rides along that cam. If turned backward, the lever might bend if forced past the "stop" that David describes. That "stop" is where the cam resets to it's lowest position.

If you remove that shutter speed dial (or look at any exploded diagram) you can immediately see why the dial should be turned in only the direction marked by the arrow.

Thank you for that Brian. I kinda remember now from years ago what the cam looks like under the shutter speed dial and again understand what's mechanically stopping rotation.

I also have a Compound shutter of about the same vintage. The mechanics of it are rather different of course. Its dial can be turned clockwise from slowest to fastest speed and then counter clockwise back from fastest to slowest, so of course it doesn't have an arrow. The stops at both ends of the speed scale feel much "harder" than the stop on my two dial set Compurs.
David

[Cor]

Gentlemen,

Thanks for the clear and elaborate answer, so to be safe I'll only turn the dial counter anti-clockwise (direction of the arrow), even changing from 1/2 to 1 second, which means a whole turn..not a big deal in the bigger scheme of working with LF..

Best,

Cor

[BrianShaw]

As a complete aside... I have a lens I really like that is in a dial-set Compur, and I still use them on a regular basis. Just last month the 1 sec started slowing down so I took it to a reapair shop for an overhaul. When I gave it to them the owner's son marveled at it's age; when I picked it up the owner marveled at the quality of the shutter. I think I read somewhere that it was last manufactured in 1925 or so. Mine was originally mopunted on a Anniversary Graphic in 1940. It is a very nice shutter and deserves to be well taken care of!

[Robbie Bedell]

Sorry to be off topic here, but Brian, I am wondering if you might share who your repair man is and how much he charges for an overhaul? I have a dial set from 1914 in beautiful condition that is just sticking on the slow speeds. I have done the research and thanks to those on this forum I have been able to take it apart and attempt to clean the inside. I have succeeded, but just a little, and I do not want to cause any damage. I have it working from 1/5 sec. and faster, but below that it is still sticky. I really want to use this lens. Thank You! Robbie Bedell

http://robbiebedell.photoshelter.com

[Bill_1856]

Cor, I have a pre-WW2 Zeiss Tessar. It only had one previous owner, never serviced, and it is definitely shimmed with paper shims.
Incidentally, I really hate rim-set Compur 2 shutters because to open the blades for focusing it must be set on "T" since there is no press-focus or blade arrestor.

[Cor]

Bill,

Thanks for the feedback, so that is the third case than, weird that these shims were needed, seems odd that they constructed the combination in such away, to (at least in case of the Angulon) the shutter blades hit the lens..

Best,

Cor