Feeding butterflies, such as this Brown Argus can be challenging subjects, demanding a mobile approach.

Speckled Wood can be particularly sensitive to flash - something I often forget if I haven't photographed one for a while. While a really acceptable open wing shot of a Speckled Wood still eludes me, I was quite pleased with this image, lit entirely with natural light. The Nikon D300 has a 'function' button, positioned conveniently on the front of the camera, that the user can programme according to their personal preference. I set mine to disable the flash output, enabling me to continue shooting without having to take my eye from the viewfinder or fiddle with the gun while working. Exposure was 1/200 sec, F11 at ISO 400. The high-resolution file is noticeably cleaner than the D2x would have produced at this setting.

The lightweight, portable set up I use for insect photography: a Nikon D300, 105mm AF-S VR Macro lens, SB800 flash gun and Lumiquest diffuser. Normally, I unclip the shoulder strap and hold the camera all the time - I find loose straps have an annoying tendency to flop forward when I'm photographing insects, either getting in front of the lens at the critical moment, or frightening the subject.

Some thoughts on choosing equipment for butterfly and dragonfly photography

Over the last year or two, I've often been asked for advice about what equipment to choose for insect photography. It's a complex subject, but I've compiled here some answers to questions I'm asked frequently. Just remember that what follows is simply my opinion, based on my own photographic experience. To use the Internet cliché: "your mileage may vary". I'd also better state from the outset that I buy all my own equipment and have no relationship, professional or otherwise, with any camera or equipment manufacturer.

Introduction

In this discussion I'm going to assume that you want to achieve the best results you can. So let's start by considering what makes a good butterfly or dragonfly photograph. For me, it's about taking pictures that show aspects of their behaviour or that capture the beauty or character of the animal well. This means often taking pictures when they're active. Over the years I've seen a lot of pictures of dew-covered butterflies and dragonflies, taken in the cool of the early morning while the insect is roosting. This frequently makes for a great picture, and it certainly makes life easier for the photographer. However, roosting is only one aspect of insect behaviour and as the day warms up, active butterflies and dragonflies present challenges that require a different strategy from the photographer. This is where modern digital cameras with auto focus lenses come into their own, because they allow the photographer to use the camera hand-held, following the subject as it moves. This approach is quite different to traditional macro or close up photography, but it allows the photographer to tackle a much wider range of photographic subjects, and creates some interesting and exciting challenges.

Compact camera or Digital SLR?

I've never used a compact digital camera for insect photography, but I've seen results achieved with them that have been pretty impressive. In their favour, compact cameras often focus close and are very light and easy to carry around. That said, digital compacts tend to be limited by their small sensors that are inherently noisier than the larger sensors fitted to DSLRs. They are also affected by the compromises that are involved in the design of their lenses and focusing systems. Such cameras suit a more casual approach, and if you're on a budget, they're worth considering. Another option are so called "bridge cameras", which have an SLR style body, but with a zoom lens that is permanently attached to the camera. These are designed for general photography and can produce excellent results, but they are unlikely to be as good for close work as a DSLR with a dedicated macro lens. Unfortunately, if you want the best tool for hand held insect photography, a DSLR is the way to go.

Full frame or crop sensor DSLR?

This is a key decision because the choice affects some of the most important aspects of close up photography. To understand this, it's worth considering the technical requirements that are needed for successful insect photography. Basically, we're talking about three things: approaching the subject without frightening it, getting it in focus quickly, then shooting a photograph of high image quality. The crop sensor camera has the edge for the first two requirements and it's probably a dead heat for the last. Here's why...

Leaving aside field craft, approaching the subject successfully is all about working distance, because the further away you are from the subject, the less likely you are to scare it. The smaller the sensor on a camera, the stronger the telephoto effect of whatever lens you are using will appear to be, allowing you to stay further away from your subject. For example, on a Nikon D300 (which has a APS-C/DX size sensor approximately 16x24mm), a 105mm macro lens will produces an image the same as a 157mm lens mounted on a camera with a so-called full frame FX sensor (24x36mm, the same size as 35mm film). The depth of field at whatever aperture you choose will remain constant, irrespective of sensor size, because it is defined by the focal length of the lens, rather than what size sensor is fitted to your camera. So, by using a crop sensor camera, you gain the advantage of greater working distance, without any reduction in depth of field. It also means a smaller, lighter lens to carry around, which is an advantage for fieldwork, and it has other benefits that I'll discuss when I look at which focal length is best later on.

Because you can achieve the same working distance with a shorter focal length lens by using a crop sensor camera, you also gain in terms of auto focusing performance, which is my second requirement. Why? Well, to use my Nikon comparison again, the 150mm lens on a full frame D3 camera is bigger and heavier than the 100mm lens needed to produce the same view attached to the APS-C sensor D300 body. The bigger lens will have heavier glass elements in it and will need to be driven in and out further to acquire focus. This takes longer and uses more energy - at least in theory. In practise, full-frame cameras tend to be top of the range models with the best focusing systems built into them, so the differences may be negligible, but all things being equal, the camera with the smaller lens should focus more quickly.

Moving on to my third requirement, image quality, what effect does the sensor size have? To get the highest image quality you want to use a low-ish ISO setting. When I started using digital cameras instead of film, I really liked the fact that they produced good results at ISO 200, which meant I'd gained one stop in speed, compared to the film I'd previously used. For a given number of mega-pixels, a larger sensor should produce cleaner, less grainy images with a better dynamic range. However, this only really becomes apparent when you use higher ISO settings. The latest generation of APS-C sensor cameras, such as the Nikon D300 and Canon 40D have enhanced noise performance anyway, so 400 is the new 200! If you take a lot of insect pictures in woodland, you might benefit from the high ISO performance offered by a larger sensor, but for most purposes, and especially in view of their other advantages, the latest crop sensor cameras are the best choice.

Which focal length is best for hand-held insect photography?

I've already talked about the advantage of keeping your distance from your subject, so you might think that a long focal length lens is better. However, this is only partly correct and a compromise is often needed. Depth of field (the amount either side of the plane of focus that is acceptably sharp) is greatly reduced when taking close-ups, so to obtain a photograph of good technical quality; you usually need a fairly small aperture, such as F11 or F16. This is bad news because it reduces your shutter speed, and you need all the speed you can get if you're hand-holding a camera with a long focal length lens! If you take the 'one over focal length' rule as a starting point; for a conventional (i.e. non VR) 100mm macro lens used on a crop sensor (DX) camera, that translates to a minimum shutter speed of 1/150 second if you want to avoid hand shake. Because of the very close working distances, any camera shake or movement tends to be exaggerated, so 1/150 is actually a bit optimistic and 1/200 is probably a better bet as a reliable minimum. The weight of your equipment is also important; longer lenses tend to be heavier and harder to hand-hold for long periods. So unless you up your ISO setting (bad idea as it reduces quality), you're constrained, and this places a practical limit on what focal length can be used with confidence without resorting to a tripod or monopod.

I find that working at F11 and ISO200, my shutter speeds are often in the 1/100 - 1/250 range. If the conditions are not ideally bright or the subject is dark - just think white admiral in woodland - the speeds can slip alarmingly into the danger zone. Because of this, I find focal lengths of around 100mm (equivalent to about 150mm on a crop sensor camera) are a good bet. However, longer lenses do have one other advantage: they create better out of focus areas because of their telephoto effect. This can make for some nice results, allowing the subject to stand out against a blurred background. With the latest cameras offering such good performance at ISO400, it may be possible to hand-hold longer lenses such as the Sigma 150mm F2.8 Macro successfully.

Do image stabilisation (VR or IS) systems offer any advantages?

In theory, VR and IS systems help to tip the balance in your favour by eliminating handshake, allowing you to use slower shutter speeds successfully. I can't comment on the IS systems built into some camera bodies because I haven't tried them, but the VR system built into Nikon's 105mm AFS VR Macro lens isn't as effective at close range as Nikon's marketing blurb claims. Still, a gain of at least one stop at typical shooting distances can be expected and this will often be the difference between success and failure. In my opinion, for hand held insect photography, there's currently no better lens available - indeed, it could have been made for the purpose. However, it mustn't be forgotten that VR/IS systems do nothing to prevent subject movement and, as shutter speeds diminish, so the chance of movement increases. Below 1/200 second, you'll stand little chance of freezing a feeding butterfly, unless you rely entirely on flash for the exposure. But there are many occasions when the subject will be stationary, but your shutter speed with have slipped to 1/60 or even less. In such circumstances, you'll be glad you have VR!

How do you set up the camera's auto focusing system?

A high quality auto focusing system is a key requirement for successful hand-held insect photography. Because depth of field is so small, using manual focus is difficult because you only have to move very slightly for the subject to be out of focus. If the subject is also moving, it becomes doubly difficult, so I've come to rely on my camera's auto focusing system. I use the AF-C setting and choose the active focusing sensor manually, keeping my finger half-pressed on the shutter the whole time so that the camera is constantly re-focusing. When things look right, I press the shutter. Focusing systems improve the higher you go up the manufacturer's camera range, so to exploit this technique effectively, buy the best camera you can afford.

What other equipment do you need?

I use flash for many of my insect photographs. The secret is to limit the flash output so that it provides enough light to fill-in any harsh shadows, but without dominating the shot or drawing attention to itself. I want the subject to appear to be lit completely naturally, and I want the background to appear natural too - you certainly don't want the butterfly to look as though it was shot at night! Typically, this means reducing the flash output by between one and two stops - more for light subjects, less for dark ones. I often turn it off completely for dragonflies and damselflies, because their bodies reflect the flash, producing unnatural highlights. I also recommend using a flash diffuser, such as a Lumiquest Ultrasoft. This softens the flash output and enables you to use the flash in bounce position with diffuser above - preventing the lens hood from casting a shadow and improving modelling. This technique produces far better results than fancy macro-flash systems at a fraction of the cost.