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The laser trigger - first real-world test

Today was the first attempt at setting up the laser and camera combination outside and leaving it to run by itself for a few hours. The setup is very simple and can be seen below:


The three tripods at the top of the image are, from left to right, the laser, an elevated seed holder and the sensor. The tripod in the bottom left corner is a Canon 7D with a carrier bag covering it in case of unexpected showers. The lens is a Canon EFS 17-55mm, so not a typical bird photography lens, but a suitable lens to use for the test.


Weather wise today it was unseasonably mild, which probably explains the lack of birds in the garden. The only birds that seemed to be around were wood pigeons. It is possible that four new tripods in the garden might have put the regular birds off too but hopefully not.

Below are the first shots captured by the rig. From a photographic point of view the setup is far from ideal, with the perch being far too close to an unsightly fence but this was purely part of the functional testing phase. In terms of testing, the results are reasonably successful.


The test did highlight a couple of problem areas however. The first is that at some point (presumably) a pigeon landed on the handle of the sensors tripod and knocked it slightly out of alignment. This can be mitigated in a few ways, either by using a more robust tripod, removing the handle from the tripod or by adding some form of deterrent.

Another issue was rogue insects breaking the beam and causing the camera to fire. This didn't happen often though and it shows how sensitive the setup actually is, which is a good situation to be in. It opens up the possibility of doing macro insect in flight shots next year when the rig has advanced a bit more. A mitigation for this situation is to use two laser and sensor pairs and only fire when both beam are broken at the same time (in all likelihood, where they intersect). Another is simply to keep the setup simple and live with the occasional insect induced false positive.

The controller is currently set up to simulate holding the shutter button down for 800ms so the number of photos taken each time the beam is broken depends on the cameras frame per second rate and the current shutter speed. For the tests today, the camera was set up in manual mode with manual focus set. Based on the conditions I went with 1/800s shutter speed at F4.5 on auto ISO. For the types of shots I'm aiming for the shutter speed will be significantly higher, but extra light will be required. This is another area of ongoing research since there are several options available, each with their own pros and cons.

So with the initial tests proving the system can work reliably it is now a case of refining the setup and capturing more birds. Until more time is put into working on lighting options the targets are likely to be the larger (and slower) birds that drop into the garden, namely magpies and rooks. Watch this space.

Even though the setup is anything but photogenic, the result doesn't look too bad after a few tweaks in photoshop.


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