Lenses
All the
major manufacturers produce a vast range of lenses suitable for every
conceivable situation, including a wide choice of macro lenses of
various focal lengths. Always check compatibility between lenses and
camera bodies by using the charts shown on the camera manufacturer
websites. Beware that camera functions may not work if you fit an
incompatible lens.
There are 3 basic types of lens available
- primes, zooms and macros. Don't be misled into thinking that the
so-called "macro" facility of zoom lenses will give you results as
good as a real macro lens, it won't. The results however are quite
acceptable to many people, and it's well worthwhile having a general
purpose zoom with a close-up facility.

Euphydryas aurinia,
18-70mm zoom set at 70mm and closest focus ©
Adrian Hoskins
Zoom lenses
Standard kit lenses, typically 18-70mm zooms, offer a reasonable
working distance and focus close enough to fill the picture with a
medium sized butterfly. Most manufacturers also offer longer zooms
such as 18-125mm or even 18-250mm. These versatile optics will cover a
huge range of subjects - butterflies, birds, sports, portraits,
landscapes etc; and can be left permanently fixed to the camera,
preventing the ingress of dust, which can get onto the image sensor
and ruin photos.
One
major disadvantage of zoom lenses is that they usually have a small
maximum aperture. This reduces viewfinder brightness making it harder
to compose photos in poor lighting conditions. Zoom lenses never focus
as closely as true macro lenses, so while they are fine for larger
butterflies, they will not let you get close enough to photograph
blues, coppers or skippers. Zooms also suffer from optical defects
such as colour fringing, and their large front elements make them
prone to flare.
Many
people find it difficult to approach nervous butterflies, and prefer
to use long zoom lenses or prime telephotos that enable them to shoot
from further away. There are disadvantages however. Firstly the lenses
are long and heavy which makes them hard to hold steady. Another
disadvantage is that the greater distance between camera and butterfly
severely limits your choice of viewpoint.
Macro-lenses
If you
are really serious about butterfly photography, particularly if you
want to photograph larvae, pupae, anatomical details etc, you will
need a proper macro lens, i.e. one that will focus continually from
infinity down to life-size without needing to fiddle with switches, or
to add close up lenses.

Essex Skipper
Thymelicus lineola ©
Adrian Hoskins
The
major manufacturers produce a range of macro lenses to cater for all
needs. The light and easy to use lenses in the 60-70mm range are fine
for the more approachable species, but butterflies are often quite
nervous, so ideally you need something longer. Most users therefore
feel happier using something in the 90-105mm range.
The best lenses
feature
internal focussing,
which keeps the length of the lens constant regardless of focus
distance and makes focussing much faster. These lenses have virtually
silent focus motors.
Some of the more expensive lenses also
feature image
stabilisation which helps to reduce blurred images caused by
camera-shake. At macro distances their effectiveness is limited but
they will still let you use a slightly slower shutter speed assuming
of course that the subject is stationary. Beware that image
stabilisation only corrects for camera shake, it does not correct for
subject movement!

To get
this close you need a macro lens that provides a magnification ratio
of 1:1 ©
Adrian Hoskins
If you
are considering buying one of the longer 150mm or 180mm macro lenses,
beware that these are a lot heavier, much more difficult to hold
steady, and slower to focus than shorter lenses. There are times when
they can be useful to photograph a distant butterfly, but for most of
the time if you approach your subject carefully you should have no
difficulty getting close with a 105mm macro.
Ultra close-ups
The egg illustrated below is about the
size of a pin head. It was photographed at 1:1 scale using a 105mm
macro lens. The resulting image was then heavily cropped and
sharpened. To photograph subjects this small however it is much better
to mount the lens on a long extension tube or bellows. These allow the
lens to focus a lot closer, down to about 2x magnification.
Unfortunately there are two major problems when using extension tubes
or bellows. Firstly the amount of light reaching the sensor is greatly
reduced, making it very difficult to see the image in the viewfinder.
Secondly such set-ups are cumbersome, and are almost impossible to use
without the aid of a strong tripod.
Another alternative is to mount a 10
dioptre close-up lens on the front of a normal macro lens. This allows
more light to reach the viewfinder, making composition and focussing a
lot easier. Close-up lenses are much cheaper than tubes or bellows.
Unfortunately their optical quality is poor, but if you use an
aperture of F11-16 the loss of sharpness is minimised and the results
are fairly acceptable.

Brown Hairstreak egg
Thecla betulae, actual size about 1mm
diameter ©
Adrian Hoskins