View Full Version : Stupid Shutter Question

14-Apr-2014, 18:53
Hello everyone, I am new to LF phtotography and I have a really stupid question. I am using a Schneider 90mm f6.8 Angulon. My question is if I place the shutter speed indicator between two settings do I get a shutter speed aprox half the difference between those settings. i.e. I if the lens has settings for 1/10th and for 1/25th, if I put the indicator between them do I get a shutter speed of aprox 1/17.5th (or there abouts)?

Thanks to all


Kevin Crisp
14-Apr-2014, 19:10
On some Compur shutters you can set between marked numbers for intermediate speeds, but only in certain ranges on the dial as low and high speeds use different gear trains. I don't know anybody who would try to eyeball a half or a third stop difference this way instead of something obtaining something more precise and predictable by changing the aperture.

If you have a very late Angulon (lucky you) in a Copal shutter, then no, it won't work since the innards are not stepless anywhere in the range.

14-Apr-2014, 19:22
this is the lens I have

Renato Tonelli
14-Apr-2014, 20:07
I would advise against it - it could damage the shutter.

15-Apr-2014, 00:23
DO NOT attempt to achieve intermediate speeds, for two reasons:
1) Firing the shutter with the speed set between marks can damage the shutter.
2) Any such exposure adjustment can be easily accomplished with the diaphragm, which is continuously adjustable.

There were a few old shutters on which intermediate speeds could be set, but each model was unique, with no
reliable pattern even for a single manufacturer. Also, only a few speeds could be varied, not all.

- Leigh

Carsten Wolff
15-Apr-2014, 02:44

Doremus Scudder
15-Apr-2014, 02:59
Just to clarify and summarize:

Shutter speeds are at discreet one-stop intervals for most shutters (and for your shutter!). Any refinements you want to make beyond that should be done with the aperture, which is continuously variable and usually marked in 1/3-stop increments.

Unless you are sure you have a shutter with intermediate speeds (edit: see the list at Carol Flutot's site linked to above), don't set the shutter-speed at in-between values; it may not good for the clockwork mechanism inside your shutter.

And, cock your shutter after setting it, test fire it, and cock it again before making your photograph.

Edit: And apologies to Leigh and Carsten for the repition; crossed posts, not paying enough attention...



15-Apr-2014, 04:21
I am not about to discredit what have been said before, on the contrary, but there are some questions I would like to raise, and some observations to make.
I do not understand how choosing an intermediate speed could damage the shutter. I would certainly advise against changing the speed after cocking as in some shutters it could break the gear, but as with everything, don't force the mechanisms. If it resists moving it's because it wasn't designed to be moved.
While I have never opened the shutter the OP is asking about, I have successfully opened, cleaned and calibrated a compound pneumatic shutter. Those I can attest that have a continuous speed setting and that the markings are just that, markings, which you can ignore if you wish.

15-Apr-2014, 05:02
I do not understand how choosing an intermediate speed could damage the shutter. l

Partial engagement of teeth in the escapement can damage the gears.

15-Apr-2014, 09:23
I have successfully opened, cleaned and calibrated a compound pneumatic shutter.

Forgive me for being blunt, but ...
having cleaned one old shutter does not qualify you as an expert, nor even as an advanced amateur.

I am a professionally-trained camera repair technician. I've serviced hundreds of LF shutters over the years.

My recommendation, stated earlier, is:
DO NOT fire a shutter that's set between speed markings.
Doing so can break parts that are no longer made or available, turning the shutter into trash.

People can accept or ignore that recommendation, as they choose.

- Leigh