DSLR Trailcam

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Published: Wednesday, 21 October 2020 10:33

DSLR Trailcam

After seeing high quality unique images of animals photographed using DSLR camera traps (trailcams), I became interested in the challenge of building one. The main components required are a DSLR, a sensor to activate the camera, cabling and electronic flashes. All components must be adequately shielded from the weather.

The most challenging part of the project was to obtain a low cost and reliable trigger that would activate the camera when the animal entered the frame. Most camera triggers are based on either passive infra-red motion detectors (PIR sensor) or beam sensors which use an invisible light beam to trigger the camera when the beam is interrupted. I  chose a beam sensor because they are virtually immune to false triggering and can be positioned so that the camera triggers when the animal appears at the desired location in the frame. The main disadvantage compared to a PIR sensor is that the beam sensor is an active device which requires considerable battery power and needs two modules instead of one.

I am familiar with Nikon gear which is the reason for building a Nikon trailcam but most of the information here would apply equally to other camera brands.

My main interest is in nocturnal images which is why this trailcam incorporates flash units. If you only want to capture animals during daylight you could make a simpler unit that does not require electronic flashes. You would probably set the camera to 'auto' exposure and you may wish to incorporate a circuit which deactivates the system at night.

For about a year I had fun with this setup but unfortunately it was cumbersome and time consuming to set up and I soon lost interest.




The camera will be left outdoors for days or weeks at a time so I purchased a cheap used Nikon D70s from Ebay. The camera must be capable of being triggered by cable which was the reason for choosing the D70s over the D70. I used a low cost  Nikkor 50mm f1.8D lens.


Trigger sensor modules

Commercially available break-beam sensors for wildlife photography are expensive so I decided to make one using a cheap consumer 'gate opener' and several other low cost components. The gate opener consists of an infrared transmitter and a receiver module shown below, which can operate over a distance of approximately 10 metres. They transmitter emits no visible light and when the mechanical switching relay of the receiver module is replaced the unit is totally silent.



Boost converters

Two low cost MT3608 voltage converters were used to boost the 3.7 volt output of the lithium cells to the operating voltage of the transmitter and receiver modules, which is around 10 volts.

Electronic flash

Suitable electronic  flash units must be capable of entering a low power standby mode when the system is inactive. They must also be able to be woken and fire when the IR beam is broken. The Nikon SB-800 is a high power flash that satisfies both requirements and can be  purchased cheaply second hand. One unit is sufficient for good results but a second can be used to add fill light to the harsh shadows produced by a single flash. Each SB-800 requires four AA cells which will perform for several weeks on standby and during that time can produce several hundred exposures.


Rechargeable Batteries

Each flash unit was powered by four 1.2 volt  'Eneloop' cells. The beam-break circuit, used seven 3.7 volt 18650 Lithium ion cells in parallel were for the transmitter and receiver modules respectively. The lithium cells could power the circuit for approximately 16 days.




Connect as shown below. Seven 18650 cells wired in parallel  (17,500 mAh) and the entire circuit is housed in an IP67 plastic box with a transparent lid to pass the IR beam.



IR Receiver

The receiver assembly is a bit more complex but it is easy to modify with moderate soldering skill.

Step 1. Modify the receiver PCB as shown below.


Step 2. Wire seven 18650 cells in parallel  (17500 mAh) and adjust the output of the boost converter to 10 volts before connecting the IR receiver.



Step 3. Wire the circuit below using two "4N26" opto-coupler IC's and 500 ohm 1/4watt resistors. Connect the white and green wires from the modified IR receiver.   Connect the focus, shutter and ground outputs to a Nikon MC-DC1 remote cord as shown below. WARNING! use a genuine Nikon plug which costs a considerable amount but unlike cheap 'Ebay' knock-off plugs, it wont let you down. Originally I used a cheap plug which failed at the critical moment and prevented me from obtaining images of an Eastern quoll.



 Step 4. Protect the unit using an IP67 weather sealed housing with a transparent lid to pass the IR beam.


Camera to flash connections

Attach one or two Nikon flash hot shoes to a Nikon camera hot shoe according to the wiring below. Use only three wires.  Test the connections by attaching the hot shoes to the camera and flash unit(s) and set the flash units to standby mode. Power on the camera and flash units, wait for the flash(es) to enter standby mode then fully depress the camera shutter release. The flash units should awaken and fire immediately on a single actuation of the shutter release button. If they do not fire there is a problem with the wiring or connections.


Finished product. Weatherproof camera/flash housings not shown


Weatherproof housings

The IR trigger sensors , the camera, the flashes and cables must be weatherproof. The IR modules are housed in waterproof plastic boxes with transparent lids, the camera is housed in a pelican case with a 'siliconed' 90mm UV filter as the window and the flashes are mounted on poles and protected using 'ziplock' bags.



These photos of a Kookaburra, Brushtail possums, Red fox and young Swamp wallaby were taken in my backyard using a single flash unit. The camera was prefocused and food was positioned beneath the beam as an attractant.


  • Locate the beam across a frequently used animal trail or a location that an animal can be attracted to. Carefully select the location to ensure pleasing image composition
  • Set camera to manual focus and manual exposure mode so you can choose the aperture and shutter speed. if desired, a low shutter speed can be used to allow ambient light to be recorded
  • Pre-focus the camera on the location where the beam will be broken
  • Flashes are positioned just behind and above the camera to the right and or left side to illuminate the animal at the desired angle.
  • Flashes are used in manual mode with the main flash set to 1/4 or 1/2 power and the second flash to 1-2 f-stops lower.
  • Select a lens aperture to give adequate depth of field in front and behind the beam and set the camera ISO for correct exposure when the main flash is set to 1/4 or 1/2 power. I do not recommend using full power settings due to long recycling times and the low number of exposures that can be obtained before the flash batteries are exhausted.
  • When the setup is complete, test it by walking through the beam and checking the image.