Page 37 - Photo Review

INSIDER

Mechanical vs

electronic shutters

WE OUTLINE THE BENEFITS AND SHORTCOMINGS OF

EACH TYPE AND EXPLAIN WHEN THEY ARE BEST USED.

Margaret Brown

he purpose of a shutter is to control
the amount of light reaching the
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mechanical shutters were the only option and
there were only two types: focal plane and
leaf. Focal plane shutters were used in SLR
cameras, while leaf shutters, named for their
leaf-shaped blades, were generally integrated
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To some degree this distinction has persisted
into the digital age, but with the arrival of
mirrorless cameras it became possible to
include three more types: 'rolling' shutters;
hybrid shutters (which combine mechanical
and electronic operation); and 'global', fully
electronic shutters.

Mechanical shutters
With a mechanical shutter, closing a blind or
blades blocks the light, while opening them
allows light to pass to the sensor. The time the
shutter remains open is known as the 'exposure'.
Being located just in front of the image plane,
focal plane shutters work with all lenses.
They consist of two travelling 'curtains' that
open to let a slit of light through. The width of
the slit and the speed at which it travels control
the exposure time.
In older cameras, the curtains moved
horizontally across the frame. In modern
cameras, the curtains move vertically, allowing
faster shutter speeds because the distance
they have to travel is shorter. Vertical-travel
shutters can support shutter speeds as high This diagram shows how a vertical travel focal plane shutter exposes a sensor with
a moving slit that lets light through. Focal plane shutters can cause moving subjects
as 1/8000 second, which is much faster than
to appear skewed to one side as they only expose part of the frame as they travel,
leaf shutters. as shown in the picture below the diagram.

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PHOTOREVIEW AUSTRALIA | Issue 75 www.photoreview.com.au