Flash photography with the Pentacon Six
Flash Synchronisation speeds with Focal Plane Shutters
Because the duration of light from an electronic flash gun is extremely short (typically a thousandth of a second or less), the time when it is discharged must be synchronised with the time when the camera shutter is fully open.
Cameras typically come with one of two types of shutter:
The “leaf shutter” is mounted within
the lens. It typically consists
of three overlapping thin metal blades. In German
it is called “Zentralverschluß”.
Focal Plane shutter
The “focal plane shutter” is mounted within
the camera – just in front of the
“focal plane”, which is where the film is located.
The Pentacon Six has a focal plane shutter – just like the Exakta 66 (all versions of it), the Kiev 60, the Kiev 88, Norita, Pentax 67, etc.
With any camera with a focal plane shutter, the whole of the film is only fully exposed at the same time at the slower speeds. The higher speeds are obtained by making the second shutter curtain begin to cross the frame before the first curtain has ended its travel. This results in a portion of the frame being exposed progressively, as the gap between the two curtains crosses the frame. The higher the shutter speed, the narrower the gap.
The highest speed at which the whole of the frame is exposed at one time is that indicated by the flash symbol on the shutter speed dial of all focal plane cameras. In the case of the Pentacon Six, that speed is about 1/25 sec. In practice, there are few occasions when one would want to use slower speeds than this with flash. The exceptions could be night scenes where the camera was mounted on a tripod and a long exposure was used to capture the main part of the scene, with flash being added to capture a detail, perhaps a person who was posing within the picture area.
If you fire an electronic flash with the shutter set at higher speeds than the sync speed, when it fires, part of the film will be obscured by part of one or part of both of the shutter curtains, and that part of the frame will not be exposed by the light from the flash. This is what you have discovered. The higher the shutter speed, the narrower will be the open slit between the two curtains, and the narrower the area of film that will receive light from the flash. This is not a fault in the Pentacon Six but a feature of all cameras that have a focal plane shutter, regardless of the make or format.
Most photographers find that most of the time a camera with a focal plane shutter is better suited to their photographic requirements than a camera with a leaf shutter in each of its lenses, and this resulted in the overwhelming market dominance worldwide of cameras with focal plane shutters from the early 1960s on.
If your particular type of photography
calls for flash synchronisation at much higher shutter
speeds, then you have two options:
But for most photography, the Pentacon Six is a great camera that produces fantastic results, including with flash.
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© TRA April 2002 Latest revision: January 2014