Two nights ago, I was batting again. I had taken delivery of a set of what are known as “Ebay triggers”, consisting of a transmitter which normally would sit on the camera’s flash shoe, and a couple of receivers which have shoes to hold a flashgun. Switch on the receivers, press the camera button and the flashguns flash. But – no through-the-lens metering, everything’s totally manual.

They solved a problem for me. I had the laser beam sensor triggering a small flash pointing to my main flash in order to set it off with a simple optical trigger, and this risked spilling light into my camera lens. This session, I had the small flash pointing at an optical trigger with the transmitter on top. I then had two flashguns, fitted with the receivers, illuminating the target breaking the laser beam. This enabled me to position the flashguns anywhere, without risk of flare in my lens.

Got it?

Trouble was, no bats. Not flying through my laser beam, anyway. However, there was a huge hatch of insects from the river which showed up as midges which needed slapping, but also as dancing red dots in the laser beam:

This photograph shows all the insects interrupting the beam in approximately ten seconds. Multiply that over the area of the pool, and it shows an incredible number of insects hatching – all in a very short time, as the activity slowed down dramatically after only a few minutes. I wonder if anyone has used a laser beam like this to study the phenomenon?

Despite the plentiful food available, there were very few bats around, and none of them flew around my backwater. I did wonder whether they were put off by one of my flashguns which was mounted over water, so tonight I laid out my equipment with nothing encroaching on the bat’s domain.

There was very little insect activity, but plenty of bats around. Bill and I held our breaths each time they approached the beam, waiting for the flash which would indicate success, but nothing happened. I went home rather despondent, but when I went through the pictures, I found that I had a photo after all:

The time on the file showed that it was taken early on, when it was still quite light, and I remembered that Bill and I had been chatting when the flash went off. Neither of us had seen a bat, and we put it down to a midge interrupting the beam.

The photograph is heavily cropped, and the bat was near the edge of the frame. It’s a great improvement on the previous photographs and is encouraging because, while there is still some motion blur, there is room for improvement – the flashguns were set at 1/16th power.

And so to Plan B. The bats were flying over open water, so the laser beam had to be set up to intercept them:

A scaffolding pole was set up in the middle of the water, to which the laser was attached. The sensor unit was set up on the shingle bank, and was connected to a small flashgun which was angled so as not to throw light into the camera lens, but activate the flash trigger on the main flashgun, pointing at the laser beam.

Last night, the bats hunted over the main pool below the bridge, but did not hunt the pool where my equipment lay in wait. Perhaps they were put off by the pole in the middle of the water? Tonight, however, they did, and I have my first pictures:

There are lessons to be learnt from this photograph. First, the red spot from the laser shows that the bat has moved only a very short distance after interrupting the laser beam before the flash went off. No problems here. Secondly, there is motion blur rather than out-of-focus blur, so next session, I must turn down the power on the flashgun in order to shorten the flash duration.

The next photograph was at the very edge of the frame, and the bat was moving away from the camera.

These bats (Daubenton’s) can catch insects on the surface of the water by scooping them up with the flap of skin joining the rear legs and tail.

This bat seems to have done just that, because it is possible to see some droplets of water falling from the bat’s back legs.

Later on, we noticed some bats apparently flying through the beam without triggering the flash. This turned out to be due to the battery in the sensor box needing re-charging, and it explained this apparently mystifying photograph:

The red lines on the right hand side is a bat flying through the laser beam without triggering the flash! I’ll make sure that doesn’t happen again …

You may recall that I was fascinated last year by the Daubenton’s bats hunting over a pool on the River Alyn, which runs into the Dee not far from Wrexham. After trying to photograph them by hand, I started a project to photograph them using a laser beam and electronic flash.

I thought that the bats were flying in and out of the mill race in the above photograph, so, having perfected my equipment over winter, I set up a laser beam across the gap. Guess what? The bats zoomed around the pool, went past the mill race opening many times, but did not enter the opening and break the beam once! Either they have changed their behaviour, or I was wrong – easy to do, maybe, as the bats did not appear until it was quite dark.

However, the flash went off several times. When I went through the pictures – there were a lot, as the camera lens is open all the time, just closing momentarily in order to avoid problems associated with long exposure times – I found that among them was this one, with a red dot in it.

Enlarging the red dot tremendously, I have this:

This is the midge that set off the flash by interrupting the laser beam, photographed from about 4 metres away with a Canon 500mm f4, proving that my focus was pretty good – note the wings and flash-illuminated legs.

So no bats, but an indication that success was possible if the laser beam was where the bats were flying!

Movie clip from a camera trap, showing a grey heron investigating a tree which has fallen in the river.