Whether you're using a dedicated macro lens, close-up lenses, DSLR or compact, the following basic principles apply when photographing insects.
(1). Make eye contact.
An insect image will have far greater impact if taken at eye level. Most insect images taken from above typically lack impact (although they may be useful for ID purposes). Here are some examples of eye-to-eye contact:
PLEASE CLICK ON ALL IMAGES TO VIEW LARGER VERSIONS:
Firstly, a small Jumping Spider (Canon 7D with MP-E 65mm macro lens, f11, 1/160, ISO 100)
Firstly, a small Jumping Spider (Canon 7D with MP-E 65mm macro lens, f11, 1/160, ISO 100)
Secondly, a Horsefly (Canon 60D with Canon MP-E 65mm macro lens, f13, 1/160, ISO 100)
Finally, a Lesser Marsh Grasshopper that looks like it's wondering what on earth I'm doing (Canon 7D with Sigma 150mm macro lens, f9, 1/100 sec, ISO 400):
(2). Maximise depth of field.
When the subject matter is highly magnified, as it often is when photographing insects, the depth of field becomes extremely shallow. In order to get as much of the insect as possible in focus it is therefore necessary to use as small an aperture as possible. If this still does not result in the entire insect being in focus then the usual trick is to focus on the insect's eye. However, one way of helping to ensure that the whole insect is in focus is to photograph the insect side-on, so that the insect is parallel to the front of the lens. This is particulartly effective for butterflies with their wings closed and for long insects such as damselflies and dragonflies.
Male Banded Demoiselle (Canon 40D with Sigma 150mm lens, f6.3, 1/200, ISO 400):
Lacewing (Canon 40D with Sigma 150mm lens, f13, 1/4 sec, ISO 200):
(3). Pay close attention to the background
Insect images typically look best if the insect is isolated against a clean background. It is therefore important to (a) try to get your subject as far away from background foliage as possible and (b) to use just enough depth of field to ensure the insect is in focus but no more than that or else the background is more cluttered than it needs to be.
Achieving (a) above, can sometimes be down to luck. Occasionally you will find a dragonfly, for example, that just happens to be on a reed or other perch with some clean space between it and the background. On other occasions you have to make your own luck by bending the perch away from the background or bending the background foliage out of sight. A good tool to help with this is a Plamp, which is basically a flexible arm with a crocodile clip at each end. One end is fixed to your tripod (or a second tripod) and the other attaches to the insect's perch. Not only does it hold the perch steady (crucial at slow shutter speeds) but it does often allow the perch to be angled away from foliage.
Achieving (b) above is a matter of choosing the right aperture. If the front of the lens is parallel to a relatively flat insect then it is possible to get all of the insect in focus at a large aperture such as f5. This will very much help to ensure that the background is nice and clean. If it's not possible to move an insect's perch away from background clutter then this is often the only option. But it does require a relatively flat insect such as a butterfly with its wings closed or a dragonfly/damselfly from the side. Here are a couple of examples, note the large aperture used in each:
Large White Butterfly (Canon 40D with Sigma 150mm lens, f5, 1/400 sec, ISO 400):
Banded Demoiselle, female (Canon 40D with Sigma 150mm lens, f6.3, 1/200, ISO 200):
In both cases, by very carefully aligning the front of the lens so that it was parallel with the insect I was able to use a large aperture (f5 and f6.3) which provided very limited depth of field and hence resulted in a nice clean background. If the lens were not perfectly parallel with the insects a smaller aperture of f9 or 10 would have been needed which would then have introduced detail into the background.
More generally, also pay attention to the colour of the background. Sometimes it's necessary to take an image and look at it through the viewfinder to see how the colours look. In the image below, for example, I purposefully shot towards a field of buttercups to provide a yellow background to complement the colours of the dragonfly:
Four-Spotted Chaser (Canon 7D with Sigma 150mm lens, f13, 1/160, ISO 400):
(4). If using natural light, don't shoot in full sun
Not a great deal more needs to be said on this point. Full sun will tend to result in harsh highlights and deep shadows and generally provides less attractive macro images. Better results will be achieved shooting in cloudy conditions since the cloud softens the light by acting in the same way as a flash diffuser. Speaking of flash...
(5) Don't be afraid to use flash
Some photographers prefer to use only natural light for macro work on the basis that the use of flash can make the image look artificial. Although this can be true if too much flash is used or if it isn't diffused well, flash does have a number of benefits. Firstly, it allows a smaller aperture to be used and hence provides greater depth of field ; secondly it picks out detail and hence can provide sharper-looking images; thirdly, given some insects' preference for lurking in the undergrowth, it provides photographic opportunities which simply wouldn't have existed if flash were not being used; finally, if lighting an image entirely by flash, the very short duration of the flash acts in the same way as a very fast shutter speed and can remove motion blur.
Although most of my images taken with the Sigma 150mm lens do use natural light alone, all of my images taken with the MP-E 65mm macro lens are lit entirely, or partly, with flash. I also tend to use my Canon 60mm lens with flash. The reason these 2 lenses lend themselves to flash use is because they have very short working distances (the distance between the end of the lens and the subject) which means it is possible to bend a heavily diffused flash gun into position so that it is very close to the subject. This is crucial to prevent harsh light. The larger the diffuser and the closer it is to the subject, the more natural looking the flash light will appear.
In terms of flashguns, the options are an external flashgun on a side bracket (e.g. a Hakuba L-H1 flash bracket, available from Ebay, which has a ball head) or a dedicated twin-head macro flashgun such as the Canon MT-24EX. Home-made diffusers are fairly easy to construct, although for an external flashgun an adapted lambency diffuser (again, see Ebay) works well. The adaptations I used to make were to cover the front with kitchen towel, to cover the sides with kitchen foil and then to tape over the kitchen foil to keep it in place. I currently use the Canon MT-24EX and THIS POST describes how I diffuse it (as well as the lambency diffuser).
The images below were lit entirely with flash.
Ladybird (Canon 7D with MP-E 65mm macro lens, f13, 1/160, ISO 100, diffused MT-24 flashgun):
Marmalade Hoverfly (Canon 5D with MP-E 65mm macro lens, f11, 1/160, ISO 400, diffused Canon 580EX flashgun):
(6). Try using a mix of flash and natural light
When lighting an image entirely with flash you will always get a black background unless you are very careful to ensure there is some foliage or petals in the background very close to the subject. Sometimes, however, it can be desirable to illuminate the subject matter using a diffused flashgun (in order to gain from greater depth of field and to freeze movement) but to allow natural light into the background. In some ways this technique provides 'the best of both worlds.' When shooting in this manner I will normally use aperture priority and will dial in -11/3 (one and one third) or even -1 2/3 (one and two thirds) negative flash exposure compensation to ensure the flash isn't too strong.
I tend to use this technique most when the sky is deep blue as I have a bit of a thing for blue skies in images! Here are a couple of examples, the first taken with the MP-E 65mm lens and the second with the Canon 60mm lens.
Ladybird (Canon 5D with MP-E 65mm lens, f11, 1/200, ISO 400, diffused MT-24 flashgun):
Juvenile Shieldbug (Canon 60D with Canon 60mm macro lens, f7, 1/200, ISO 400, diffused MT-24 flashgun):
(7). Capture interesting behaviour or action
Images are often more interesting if they contain some natural behaviour or action rather rather than merely a static insect. Here are a few examples.
Here a Black Ant is 'herding' aphids in order to milk them for their honeydew (Canon 450D with MP-E 65 macro lens, f10, 1/160 sec, ISO 100):
Secondly, this Dung Fly is about to devour a smaller fly that it has caught (Canon 30D with MP-E 65 lens, f14, 1/160 sec, ISO 100):
This Large Red Damselfly is transforming from its aquatic nymph stage into an adult damselfly (Canon 7D with Sigma 150mm macro lens, f13, 1/100, ISO 400):
Finally, this Black Ant is stopping for a drink on a foxglove (Canon 60D with MP-E 65mm lens, f10, 1/160, ISO 100):
(8) Capture the insect's environment
Most of the above shots show the insect in isolation from its surroundings. Sometimes however, including the insect's environment can provide a more interesting image. A wide angle lens with close focussing ability, or a fisheye lens, are the best lenses for this sort of shot and it works best with fairly large insects.
A Brown Hawker dragonfly (Canon 7D with Tokina 10-17mm fisheye lens, f11, 1/640, ISO 400):
A Brown Lipped Snail (Canon 40D with Tokina 10-17mm fisheye lens, f16, 1/250, ISO 320):
(9). If your equipment allows, why not try high magnification macro? Although a lens such as the Canon MP-E 65mm is ideal for this sort of image, you don't have to break the bank to shoot high magnification images. Try reversing a basic 50mm lens (you can get adapters to fit the reversed lens to the camera) or try extension tubes on a macro lens (the smaller the focal length of the macro lens the greater the effect of the extension tubes) or try clipping a Raynox DCR-150 or DCR-250 close up lens onto a macro lens.
Obviously the greater the level of magnification the shallower the depth of field, so some care is needed to ensure that the insect's eye is in focus. Here are some examples;
This tiny Globular Springtail is around 2mm in length and was here photographed wondering around a frost covered rock in the middle of winter (Canon 40D with MP- E 65 lens, f9, 1/160, ISO 100):
A Jumping Spider (Canon 30D and MPE-65 lens, f8, 1/160, ISO 100):
A Large Red Damselfly (Canon 450D with MP-E 65mm lens, f10, 1/160, ISO 100, diffused Canon 580EX flashgun):
All comments welcome, particularly if you have found any of the above helpful or if you would like me to clarify any points.