K i t Z o n e T
Help me buy a...
Telephoto lens
A telephoto lens is a key step in expanding your camera system
Sigma
150-600mm
f/5-6.3 DG OS
HSM Sports
£1,299/$1,799
For long-range
subjects, you
need a super-telephoto
lens. This good-quality Sigma
is available for Canon and
Nikon DSLRs; an optional
teleconverter extends
its range still further.Canon EF
70-200mm
f/2.8 L IS III
USM
£2,099/$1,899
A 70-200mm
f/2.8 is a
‘must-have’ for
many professional
photographers. The
constant maximum
aperture really pushes
up the price, though!Good, better, best
Three telephotos at different priceselephoto lenses magnify
distant subjects so that
you can still fill the frame
when you can’t get close
enough with your
camera’s kit lens.
They’re essential for sports and
wildlife photographers, for example.
Telephoto lenses come in many different
sizes; while many ‘amateur’ lenses are
comparatively light and affordable,
professional lenses can be extremely
expensive. They also vary in their
magnification, or focal length; the further
away your subjects are from the camera,
the longer the focal length you need.
Most telephoto lenses are zooms,
which means you can easily adjust
the magnification and adapt to different
shooting distances, but some specialised
and professional lenses are fixed-focal-
length ‘prime’ lenses.
Choosing a telephoto is not necessarily
straightforward, especially when you’re
just starting out, which is where this guideis designed to help. Once you know what
you want to photograph and how much
you’re prepared to spend, it’s a lot easier to
choose the right telephoto lens for the job.1 Telephoto types
Most people start out with a budget
telephoto zoom, but you can also get
more expensive ‘constant aperture’
telephotos, which give faster shutter
speeds and shallower depth of field
and are preferred by experts and pros.
For super long-range subjects like birds
and aircraft, you need a super-telephoto
lens with a much longer focal length.2 Full frame vs APS-C
With kit lenses and wide-angle lenses,
you have to get a lens designed for your
camera’s specific sensor size, such as
APS-C or full-frame. With telephotos it’s
different; if you have a Canon or Nikon
DSLR, for example, a full-frame telephoto
is the best choice because it will work on
an APS-C camera too – and the 1.5x(non-Canon cameras) or 1.6x (Canon
cameras) crop factor of the smaller sensor
will give your telephoto lens more reach!3 Maximum aperture
Most telephoto zooms have a maximum
aperture that changes as you zoom in.
This might appear in the specifications
as ‘f/4-5.6’, for example. This means
your shutter speeds will be slower at
longer zoom settings, right where you
really want them to be faster!
The aperture changes because
maintaining a wide maximum aperture
at long zoom settings needs a lot of very
expensive glassware; so while ‘constant-
aperture’ zooms are desirable, they are
heavy, often limited in their zoom range,
and cost a great deal of money. For most
users, a variable-aperture zoom is a better
compromise in terms of weight and cost.4 Image stabilisation
Some cameras have in-body stabilisation
systems to help you get sharp shots,
but most telephoto lenses have image
stabilisation built into the lens. Some kind
of stabilisation is essential for long-range
photography, unless you’re using a tripod.5 Weather sealing
It’s worth getting weather-sealed lenses,
although a rain cover is the best solution
for prolonged shooting in wet weather.6 Focus limiters
Focusing can be a particular challenge
with big telephoto lenses. Some makers
offer a ‘focus limiter’ which restricts the
close-focusing range of the lens and sets
it to cover medium to long distances
only. This can greatly speed up the focus
response, because the lens is not trying
to check such a wide focus range.Ta m r o n
70-300mm
f/4-5.6 SP
Di VC USD
£329/$449
This is a popular
zoom range for
an all-purpose telephoto
lens. The Tamron is also
cheaper than similar
own-brand lenses from
Canon and Nikon and is
available in both fittings.130 DIGITAL CAMERA^ AUGUST 2019 http://www.digitalcameraworld.com