View Full Version : Flash and synch speeds on Ilex Acme shutter

28-Apr-2004, 20:25
Just now looking into using a remote flash set up with my lenses in Ilex Acme shutters. I understand pretty much about the seperate cocking lever and setting options for the type of flash being used but I need to know if I need to use any aditional specific shutter speed for proper synch. For example on 35mm the synch speed often is 1/60th. Do I retain control over both speed and aperture?

Thanks all.

David A. Goldfarb
28-Apr-2004, 20:55
It should sync at any speed. Sometimes if you have a high speed leaf shutter and a powerful studio strobe setup you need to avoid the shutter's top speed, because it could actually be longer than or close to the flash duration, but I don't think any Ilex shutter has that high a sync speed, so it shouldn't be an issue.

Ernest Purdum
29-Apr-2004, 07:32
The focal plane shutters of many 35mm cameras don't open all the way at higher speeds, just a slit passes by in front of the film. Exposure has to be at a speed slow enough that the shutter opens all the way. <p

Leaf shutters always open fully, so the flash has to go off at the right time but the speed doesn't matter.

You retain full control.

Bob Salomon
29-Apr-2004, 07:56
You can very easily check at which speeds your shutter will properly synch with strobe if it does not have X sych setting.

Take the lens off the camera and fire it while facing a wall and looking through the back of the lens (you do not have to hold it against your face to do this. If you see a full circle of white light from the flash that speed synchs with strobe. If you don't see a full circle of white light while looking through the back of the lens it does not synch with strobe at that speed.

With electronic flash and a leaf shutter you have flash synch at every speed that allows you to see the full illuminated circle.

With your 35mm camera with a focal plane shutter you only can synch an electronic flash at the fastest shutter speed that allows the shutter to be open for the full frame rather then a shutter speed that travels across the frame as a slit.

If your old shutter has a marked X synch then it synchs at all speeds.

Bob Fowler
29-Apr-2004, 08:47
Just to add a bit here...

Some studio strobes have rather long flash durations (>1/300 sec) which require you to use slower shutter speeds. Consider that the marked shutter speed of leaf shutters is NOT the amount of time that the shutter is "full open", but rather measured as a function of total open time. At X sync, the flash doesn't fire until the blades hit the full open position so there is a chance that you'll waste some usable flash power if you use too high a shutter speed as the shutter blades will be in motion while the flash is still firing.