Photographing Tree frogs in the Amazon rainforest

Amphibian ark has declared 2008 as 'The Year of the Frog'. Why? Because amphibians are in trouble, and it isn't just a few species - almost half of them are in danger of extinction! Amphibians are particularly sensitive to changes in their environment and pollution due to their moist, absorbent skin but they face another enemy, Chytrid fungus, which is killing huge numbers all around the world. The Year of the Frog aims to raise awareness of the plight of the amphibians so that something can be done to protect them.

The Amazon Rainforest is probably the most species rich habitat on the planet. Take a walk through it during the day and you'll see and hear birds flitting between the branches, butterflies of all colours and sizes fluttering past and maybe even some monkeys looking down at you from the canopy. There is a lot of life around but after the initial dawn chorus things quieten down and it can actually seem quite quiet and empty. However, as the sun goes down the peace is shattered. First to wake are the crickets and katydids but they are soon joined by the real chorus of the night – the frogs. This is what I've been waiting for so I finish my dinner of Piranha and Yucca chips and head out to find them.

I don't have to go far. Heavy rain earlier in the day has left a deep pool on the edge of our camp and I can hear the chirps of some little tree frogs in the bushes around the pool and not much further away there is the soft hooting of a smoky jungle frog. The pool will provide a good nursery for tadpoles so the males are calling to proclaim their territory and attract females.

But I'm not here just to listen to them; I want to photograph them, which means I have to find them first. It’s surprising how hard it can be to find something that is advertising itself so clearly but some of these tree frogs are only about an inch long and it’s hard to pinpoint exactly where the sound is coming from. More often than not they will be high up in the canopy, out of reach, but soon I find a little Hyla rhodopepla that has come down to the pool. It's a tiny yellow frog with huge eyes which take up half its head and big sticky toe-pads. These are the features that I think make tree frogs so cute and photogenic. Not long after I find a well camouflaged marbled tree frog and then a much larger bromeliad tree frog; it's turning into a good night's hunting.

Tree frogs presented many new photographic challenges for me. First of all was the lighting. Like most wildlife photographers I like to use natural lighting as much as possible so avoid using a flash, but for nocturnal animals this obviously isn't possible. I could of course try to find one during the day but a sleeping frog doesn't make a very interesting subject so I had to learn to get attractive light from a flash. The first step was to take the flash off the camera. On camera flash gives very flat looking photos as there are no shadows visible. Moving the flash off to one side a bit gives more depth to the image. The next problem with flash is that, as a point source, it produces harsh directional lighting with very dark shadows. To make matters worse the moist skin of amphibians is very reflective giving harsh highlights. There are two main ways of getting around this. You can use a second flash or a reflector to provide some fill light in the shadows or you can soften the flash with a diffuser which has the effect of increasing the size of the light source. I prefer the latter method because carrying one flash is enough of an extra burden when working in the heat and humidity of the rainforest. A polarising filter can help reduce the reflections and control the highlights but at the cost of putting more burden on the flashes.

The next problem was one I was more familiar with from other macro work. At high magnifications depth of field is very shallow. Even with a tiny aperture around f/20 you only get a few millimetres in sharp focus so when composing you have to be selective about what you want sharp. I nearly always make the eyes of my subject the priority here and then I'll try and get any other defining features, such as the toe-pads or unusual colouration, in the focus plane. At high magnifications the easiest way to focus is to set the magnification you want and move the camera back and forward until the subject is in focus. This is especially true at night when there isn't enough light to for the camera's autofocus anyway.

With these issues under control I started getting some pleasing results but after a while a theme started to show – black backgrounds. This is a common result of using flash as the light from a flash decreases exponentially with distance so unless the background is very close it will hardly be lit at all. For nocturnal animals I don't actually mind the effect but it does get a bit monotonous so I started to look for ways of avoiding it. One way would be to use a second flash to light up the background. This is fine if have the time to set up but with a subject that is constantly jumping from tree to tree it can be tricky. It's often easier to compose the shot so that there is a background close enough to get a decent amount of light on it.

Over the time I spent in the rainforest I learnt a lot about photographing these wonderful amphibians but there are always more things to learn and new techniques to try (and of course there's more than just frogs there) so I already have my next trip planed. Earth Sessions has teamed up with the remote indigenous Quechua community of Pavacachi in Ecuador, where these photos where taken, to try and protect the rainforest. Pavacachi is a fantastic location because it is so remote and, unlike many indigenous communities, the locals hunt very little. Thanks to this the wildlife is second to none in Amazonian Ecuador with 12 primate species recorded, countless bird species and even sightings of jaguars Tapir and giant anacondas!

In order to preserve the 53 000 hectares of pristine rainforest that the community owns they need to make it economically viable and they are trying to do this through ecotourism. To find out more about Earth Sessions or to join one of their expeditions visit www.earthsessions.com