Flash photography with the Pentacon Six
How to get
The previous page (here) explains
how electronic flash works on cameras with Focal Plane
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.
The same restrictions on
maximum usable flash sync speed apply in the 21st
century (even on digital cameras) as they did 50 or more
On 35mm film cameras, this was generally
1/60 sec. (See, for instance, the Minolta SR-T
101.) The SR-T 101, like the earliest 35mm film
cameras (which were not SLRs) had two shutter curtains
that travelled across the frame horizontally,
thus having to cover a distance of 36mm (the width of
the frame in a 35mm film camera).
Medium format cameras with a focal plane
shutter have a problem: the frame is bigger, so even if
the shutter moves as fast as it does on a 35mm camera,
it will take longer to traverse the frame. This
means that the fastest speed at which the whole
of the frame will be simultaneously uncovered must be
slower, typically about 1/30 sec.
In this, the Pentacon Six is no better
and no worse than any other medium format camera with a
focal plane shutter.
(Conversely, many digital cameras have a
sensor that is much smaller than the
standard 35mm film frame. Because of this, the
time that the focal plane shutter needs to cross the
sensor is shorter and the shutter speed at which the
whole of the sensor is simultaneously uncovered is
higher, often 1/200 sec.)
But there is a way to get round
As stated above, the duration of the
light output from an electronic flash is extremely
short, typically 1/1000 sec or less. But if you
could get a flash gun that would produce a flash that
would last several milliseconds, it could start
transmitting light while a narrow slit of the film was
being exposed (at a high shutter speed) and continue
transmitting light at the same level until that slit had
reached the end of its travel and the whole of the frame
had been exposed. In the Pentacon Six, the time
taken for the two shutter curtains to traverse the frame
is approximately 35 milliseconds.
The effect would be to give
flash sync at all shutter speeds.
And the good news is
that such flashguns do exist!
They are called Focal Plane
Flashguns, or "FP" flashguns for
Note that these flashguns take "FP" flash
bulbs, which are single-use bulbs. And they are still
available in the 21st century. They have a
constant luminescence period of approximately 40 to 50
milliseconds, more than enough to provide even exposure
across the whole of the frame.
However, you can't just mount an FP
flashgun on your Pentacon Six, which (like all other
cameras) is synchronised to fire the flash when the
shutter opens. What you need is a circuit
that will trigger the flash 16.5 milliseconds before
the shutter opens. This is called an "FP" circuit,
whereas a standard electronic flash circuit is called an
The Pentacon Six was designed to
incorporate an "FP" circuit and an "X" circuit, and
the chassis on all of them has the space to
accommodate both circuits, each with its own coaxial
sync socket. However, virtually
all Pentacon Sixes left the factory with only the "X"
flash sync circuit installed. This was because by
the mid 1960s most photographers had adopted electronic
flashguns and so had no need for a camera with an "FP"
socket. Except in one country!
My thanks to CB in Berlin for providing much of the information on which this page is based!
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© TRA January 2014