Using extension tubes/bellows and tele-extenders.
Canon 25mm extension tube
All three macro lenses accept an extension tube or stack of
tubes. Extension tubes contains no optical elements, and are available
in different lengths. The effect of the tube is to enable the
lens to focus closer than it did previously as it is effectively
now mounted further from the camera body. In other words, by enabling
you to get closer to the subject, the magnification will increase
(and depth of field will decrease proportionally.)
In fact, an extension tube can be used to increase magnification
by reducing working distance on any lens - it just won't now focus
to infinity. Bird photographers sometimes use a tube between a
super-telephoto lens and the camera to enable them to get closer
to an accommodating bird than the minimum focusing distance of
the lens will normally allow. This is how a really close head-shot
can be made with a long lens. Before investing in a macro lens,
it might be worth trying an extension tube behind a normal 50mm
lens or short telephoto if you happen to own one.
With an extension tube you are sacrificing working distance for
gains in magnification. One downside is that light has a longer
path to make down through the lens and then through the extension
tube to the film or image sensor of the camera. The extension
tube therefore robs you of a stop or more of light, depending
on which length tube you opt for.
Modern automatic extension tubes initially appear expensive considering
they contain no optics, but they do have to be fitted with all
the electrical contacts necessary to pass information between
the lens and the camera. Before automatic tubes were available,
through- the-lens metering was not possible and exposure allowances
had to be made for the presence of the tube.
I once had a bad experience with a cheap set of tubes, which caused
intermittent flare as they had not been adequately protected against
internal reflection. Since that time I have only used the manufacturers
own tube (I only currently own a Canon 25mm tube).
Bellows and focusing rails are specialist equipment for those
requiring magnifications far beyond life size. They consist of
a light-proof set of corrugated bellows which are fitted between
the lens and the camera. The lens can be moved backwards and forwards
on the bellows rail - effectively becoming a huge and infinitely
adjustable extension tube - with the accompanying huge loss of
light. Their use tends to be restricted to the studio where sufficient
light and control of vibration at such high magnification is easier
to control than in the field.
One other use of an extension tube.
The next section deals with tele-extenders. Unfortunately Canon's
1.4x and 2x extenders are only designed to work with the "L"
lenses, so physically don't fit the 50mm and 100mm macro - which
is a shame. However, all is not lost, as there is a workaround
- simply fit a short extension tube between the lens and the extender.
The Canon 2x Extender
Tele extenders are far more familiar to bird or wildlife photographers
using telephoto lenses than those interested in close-up photography.
They extend the focal length of the lens - so a 500mm f4 lens
becomes a 1000mm f8 when fitted with a 2x extender for example.
Extenders used to have a bad reputation for image quality, but
the latest manufacturers-own extenders are optically matched to
the lenses they are intended for and provide superb quality. An
extender has glass elements inside it that effectively magnify
whatever is in front of it by a factor of 1.4x or 2x depending
on which extender is in use. They will also multiply lens defects
- so should only be used with the finest prime lenses for optimal
So how is this of use to close-up photography ?
Put a 1.4x converter behind a 180mm/f3.5 macro lens for example,
and you will have a 252 mm f5 lens with a 1.4 greater magnification
and working distance. This (in combination with a monopod) is
one of my favourite combinations for photographing butterflies
on a sunny day, when the one stop light-loss penalty inflicted
is less of an issue than getting close to hyperactive insects.
A 2x converter will make the 180mm lens effectively 360mm but
will rob 2 stops of light. If you set the lens to 1:1 and move
in closer until focus is achieved, you will be working a 2:1 or
twice life size.
As previously mentioned, by fitting an extension tube between
a 50mm or 100mm lens and the extender, it can be physically made
to fit. Unless the subject and camera is totally static, it is
more practical to use flash as the sole light source when using
such a set-up. Here is an uncropped image taken with this combination.
The quality of the image is still extremely high, despite the
insertion of two items between the lens and the camera:
Image of an elephant hawk moth taken with 100mm macro plus
extension tube plus a 2x extender between the tube and the
Image quality comparisons of the 180mm lens with
Here is the starting image again, taken with the bare 180mm macro.
This viewfinder image size was used as the basis for matching
the other images taken when converters were added. By varying
the distance of the banknote to the camera, approximately the
same magnification was achieved in each case. The rectangle represents
the magnified area in the unsharpened 100% crops that
180mm lens, no extender at 73cm distance. 100% crop
180mm lens, Canon 1.4x mk II extender at 88cm distance.
180mm lens, canon 2x converter mk II at 118cm distance.
Conclusions from these tests:
The 1.4x extender shows negligible image degradation.
The 2x extender shows some degradation when the bank note image
is matched for size in the viewfinder. Not a bad result considering
that this is a 100% crop of the image and the image is not sharpened.
However, it gets a lot better for the 2x converter yet, as this
test does not really show the results of how it would be used
in the field with a flighty subject such as a dragonfly - which
is very hard to approach without scaring it off. This is where
the benefit of the extra focal length pays off. Here are the un
cropped images from the same shooting
distance (73cm) :
180mm macro - no converter at 73cm working distance
180mm macro plus 1.4x converter (equivalent to focal length
of 252 mm) at 73cm working distance
180mm macro plus 2x converter (equivalent to focal length
of 360mm) at 73cm working distance
The 2x converter now looks far more impressive !
Finally here is a real world image of a rare Wood white butterfly
taken with the 180mm macro plus 2x converter. Exposure: 1/100
sec f7.1 ISO 250 (Evaluative metering + 1 exposure compensation).
Notice how the background bokeh is perfectly smooth despite nearby
grass stems behind the subject- that is thanks to the 360mm combined
focal length. The depth of field was so tiny, that it was imperative
to get the camera exactly into the plane of the insect's wings.
Which macro lens should I buy ?
In this article, I have tried to illustrate that there is no
one macro lens that does it all - they are horses for courses:
If you on a strict budget or only rarely dabble in macro work,
or want to travel light, do copy or product work in a studio at
close range - then the 50mm macro lens is the one for you - it
is a real bargain.
If you are interested in photographing dragonflies or butterflies
that are very flighty, then a 180mm macro (possibly even fitted
with an extender for even greater working distance) is a huge
advantage. You will also have the ability to blur backgrounds
considerably with this lens, but you will need deep pockets -
this is an expensive lens. The Sigma 150mm and 180mm macros have
a very devout following also as they are of very high optical
quality and are cheaper than the manufacturer's own.
Then there is the 100mm macro. I haven't mentioned it so much
in this article, as the other two lenses represent the extremes
and better illustrate the points I have been trying to make. However,
my recommendation would be that if you only wish to own one macro
lens, then this is the one to buy. It is the best compromise between
price, size, weight, working distance etc. Although not designated
"L" status, the image quality is as good as the L lens
in my opinion. When working with flash, you feel to be at a sensible
working distance from your subject, and you are not normally working
so close that you are casting shadows over your subject by the
If you are interested in photographing plants, then the 100mm
macro is an ideal lens. The 180mm only beats it when you are trying
to isolate the plant from a highly distracting background.
For many years, I only owned the 100mm macro and only added the
other two as the icing on the cake as funds permitted. In reality
I could still get by with just this lens if I had to. My lens
is the old pre-USM motor lens. The latest version has internal
focusing, is much quicker and quieter to autofocus but has similar
optical quality I believe. As I almost always focus manually in
close-up I don't consider this to be much of a hardship so haven't
yet felt the need to upgrade.
Although I have no experience of them, there are the two other
macros that I mentioned at the beginning of this article:
The MP-E 65mm f2.8 1-5X Macro Lens for ultra close-up by experienced
users only I would suggest. The EFS 60mm f2.8 which only fits
the 1.6x cameras with the "S" mount. You will also need
to ensure, that if you are buying an extension tube for this lens,
it must also be the latest "S" version.
I should also mention again that Tamron and Sigma make some optically
excellent macro lenses that may be worth investigating as they
may provide equivalent quality to the manufacturer's own at a
Do I need to use a tripod with these lenses?
Working at high magnification demands excellent technique if sharp
images are to be obtained.If you are using flash as the sole light
source, then theoretically you do not need a tripod as the flash
duration is so short (around 1/50,000th of a second). There is
no chance of camera shake at this speed and unless you are photographing
something extraordinarily rapid, subject movement is not an issue
either. However, I still use a tripod whenever possible, even
when using flash, as the depth of field is so minute, that it
is very difficult not to have swayed/moved in or out a little
in the time it takes to press the shutter.The easiest way of photographing
in close up with modern TTL/ETTL flash is to set the camera to
manual, set the aperture to f22 for good depth of field and the
shutterspeed to the maximum flash/camera synch speed (typically
1/125th - 1/250th sec) and shoot away.
If you are using natural daylight or daylight plus fill-in flash
for your close-up work, then I recommend setting the camera to
aperture priority (AV mode), start at f22 and see what shutterspeed
the camera wants to set. Even in bright light, it will be a very
slow setting, so a sturdy tripod (or monopod if a tripod is impractical)
becomes essential. If the shutterspeed is around 1/10th to 1 second,
then I would use a remote cable release (to prevent transmitting
vibration to the camera as the shutter is depressed). I also routinely
use mirror-lock up at these speeds as the vibration of the camera's
mirror slapping around is sufficient to soften images a little.
Also remember, that if you are using flash as a fill-in, it is
only being used to reduce shadows, not light the subject - so
don't rely on the flash freezing movement - it won't - as the
slow shutterspeed that the camera will select will enable a bucket
load of camera shake to occur regardless !