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DSLR camera trap

Previous experiments on this blog used a breaking laser beam to trigger the camera. While this approach has some advantages there are a few major disadvantages too. The main disadvantage is the requirement to set up and accurately align lasers around the target. In certain situations this isn't an issue, but in many cases it is completely infeasible.

The goal for well over a year now has been to design a module that will slip over the eye piece on a DSLR and will only fire when something changes in the field of view. The idea being you set up your camera with whatever lens you want, frame up and focus on the target (an empty perch for example) and as soon as the picture changes, the camera fires.

In theory this sounds like a simple problem to solve but in reality I've encountered many headaches that have stopped me building the ultra low latency system I envisaged. Rather than allowing these roadblocks to halt all progress though I've decided to work on a simpler system that uses off-the-shelf components and open source software.


What you are looking at here is a DSLR with an inexpensive USB microscope attached to the viewfinder via a custom 3D printed mount. The microscope, which is effectively a webcam as far as the computer is concerned, is connected to a Raspberry Pi 4 which is running the open source software Motion. This software is configured so that whenever motion is detected the camera triggers. The downside is that the latency is noticeable (probably in the region of 0.3-0.5 seconds so comparable to a commercial trail camera). This means that it is suitable to capture, say, a buzzard landing on a branch and perching there, but it won't be fast enough to capture a blue tit coming in to land on a feeder.

Here are a few example shots from the very first test session. 
244mm f/7.1 @ 1/500 ISO 500

24mm f/8 @ 1/500 ISO 250

Video footage of the last image can be seen here, and shows the reaction speed of the setup. Note that the rapid fire shutter speed was because I was trying to get an action shot. The number of shots can be configured from the software.

Right now the project is still in its infancy. I'm in the process of testing out different parameters but essentially the proof of concept works pretty well. If anyone out there has been looking for this type of system to convert their DSLR into a camera trap, let me know. I'm keen to work with wildlife photographers who have projects this could help out with. Email me at cameratriggeruk@gmail.com.

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