http://www.digitalcameraworld.com APRIL 2020 DIGITAL CAMERA^61
CAMERA COLLEGECamera skills Close-ups
Don’t rely on stabilisation for macro workImage stabilisers are rated
in stops, which is a measure
of exposure. One stop is
equivalent to the shutter
speed being either doubled
or halved. So going from
1/30 sec to 1/60 sec is one
stop faster, and going from
1/30 sec to 1/15 sec is
one stop slower.
When a lens or camera
says it offers up to five stops
of stabilisation, this means
the effect (on camera
shake) is equivalent to using
a shutter speed five stops
faster than is set on the
camera. The rule of thumb
for sharp handheld shots
is that the shutter speed
should be no slower than
the focal length of the lens- so 1/500 sec for a
500mm lens. With a five-
stop stabiliser, in theory
that could drop to 1/15 sec
with similar results to using
1/500 sec. We say ‘in
theory’ because it can be
hard to keep a big 500mm
lens still at this speed.Camera skills Using stops
What a stabiliser’s rating actually means
Although macro lenses
often include image
stabilisation, its effect
actually decreases the
closer that the lens gets to
the subject. As a result, for
1:1 work it’s usually better to
use the camera on a tripod.Besides, the chances are
you’ll switch to manual
focusing when shooting
extreme close-ups, in which
case keeping the camera
locked in position will allow
you to focus the lens with
greater precision.Reduced effect Image stabilisation can reduce shakes
with a macro lens, but the effect drops off as you move inWhen to switch
it on (or off)
Why it’s sometimes good to give IS a rest
There are many situations where stabilisation really
makes a difference between a sharp shot and a soft
one. It also gives you more options when it comes to
exposure, allowing you to combine an optimum aperture,
shutter speed and ISO that might otherwise give blurred
results. There are a few times, however, where it may be
better to switch it off altogether...1 Low light
As light levels drop,
you’re going to encounter
slower shutter speeds. If
you don’t want to (or you
can’t) open the aperture
or increase the ISO, image
stabilisation can enable
you to shoot for longer.2 Depth of field
If you want to use a
small aperture to increase
the depth of field – such
as when you’re shooting a
landscape – then you’ll lose
light. Image stabilisation
can compensate for
this, so turn it on.3 Tripod work
Some stabilisation
systems can detect when
the camera is on a tripod
and will stop working. Others
can’t do this, so switch it
off to be safe, otherwise
you could actually end
up with blurred shots!4 More power
Image stabilisation
draws its power from the
camera battery, so if you’re
really running short of juice,
it may be better to switch
off the image stabilisation
system (along with other
battery hogs, such as
Wi-Fi and autofocus).