Trail Camera Noise: Part 1 — Clicks
Animals are sometimes startled by trail cameras as the cameras are taking photos and videos. This happens frequently at night — likely due to the IR or white flash. However, sometimes animals seem startled even in the day. Given how sensitive animals are to sound in their environments, they might be startled by trail camera noise. Some trail cameras definitely produce “clicks” from the IR Filter, and others an ultrasonic “squeal” from the camera’s power supply. In this series of two posts, I will listen carefully to several models of trail cameras. In part 1, I will focus on the clicking noise made by the IR filter in most trail cameras. Part 2 will cover ultrasonic noise.
Can Animals Hear Trail Cameras?
A paper by Paul Meek and colleagues answers this question in 2014 in their title, “Camera Traps Can Be Heard and Seen by Animals.” (See References). This paper looks at both audible and visible trail camera noise in the context of the sensory capacity of animals to draw this conclusion. Time has passed since 2014, and cameras have improved in many ways. Even so, most trail cameras will make a distinct click in some cases before taking a photo or video. Where does this noise come from?
Clicks From the IR Filter
Most trail cameras use an electrically driven mechanical IR filter covering a single image sensor. The filter is engaged during daylight shots, and disengaged during night shots. This filters out the (unwanted) IR from daytime shots (which would otherwise make the images pink (see How (some) Trail Cameras Fail), while letting in the IR from the IR LEDs at night. Importantly, it allows the camera to take daytime color and night-time IR black-and-white images while using a single image sensor.
Not all trail cameras use IR filters. Some Reconyx models (e.g. the XR6), and Browning (Patriot) are among the exceptions. Such cameras use two image sensors instead, one with an IR filter, and one without for day and night time photos, respectively. Therefore there is no moving IR filter, and no associated IR filter noise.
In the video below, I removed the IR Filter mechanism from an Exodus trail camera. I then removed the plastic top cover so to show the inner workings. For scale, the whole assembly is a little less than an inch in diameter. The IR filter is visible as a thin, transparent, slightly red-tinged square that moves in and out of the light path through the center of the unit. I used a AA battery to actuate the the filter through several cycles by hand. Note that the movement of the filter happens very quickly. The movement itself is not resolvable even at 1/10 speed, although the click in the soundtrack becomes more of a “thud” at the slower speed.
When Do Trail Cameras Click?
None of the cameras with IR filters I tested made a click on every photo or video. Instead, all made a “strong” click when the lighting conditions of the current photo or video differed from the lighting conditions of the previous photo or video. I.e. if the previous video was at night (IR filter disengaged), a “Strong” click is made to engage the IR filter for a following daytime shot. Similarly, if the last shot was during the day (IR filter engaged), a “Strong” click is made when the next shot is at night to disengage the IR filter.
The older Moultrie D900i made also made a “weak” click a second or two after a video completed. On analyzing the recording, it seemed that this weak click had a different structure than the IR filter click and is likely caused by the IR filter motor actuating, but not actually moving the IR filter, which is already in the correct position.
How Impactful Are IR Filter Clicks?
The good news is that for trail cameras with an IR filter, the IR filter click only occurs when the lighting conditions are different from one photo/video sequence to the next. Thus, a camera which takes a video during the day, will generate an IR Filter “click” on the first video of the night. Subsequent night videos will not generate a click, as the camera does not need to change the IR filter. However, the first trigger of the next day will elicit a change in the IR Filter, and therefore generate a click.
In camera sets with a lot of wildlife, and therefore a lot of day an night triggers, this means only the first animal of the day/night will ne exposed to an IR filter click. For the rest, the camera will appear silent (at least as far as IR filter clicks go). However, for sets with relatively few triggers per day, and mix of day and night triggers, almost every trigger will be accompanied by an audible click.
Summary of Trail Camera Noise — “Clicking”
The table below summarizes whether cameras from our collection have movable IR filters, resulting in “clicking” noise. To answer the question posed with the introductory photo, it seems quite possible that a “click” from the Exodus Lift 1 piqued the bear’s interest in our camera.
| Manufacturer | Model | IR Filter “Click” |
| Browning | Recon Force FHD Platinum (BTC-7FHD-P) | Yes |
| | Recon Force Advantage (BTC-7A) | Yes |
| | Spec Ops Advantage (BTC-8A) | Yes |
| Exodus | Lift 1 | Yes |
| | Lift 2 | Yes |
| Foxelli | 14 MP FULL HD TRAIL CAMERA (DL1) | Yes |
| Moultrie | D900i | Yes |
| Reconyx | UltraFire Professional Covert (WP9) | No |
| | UltraFire Covert (XR6) | No |
Next Up: Ultrasonic Squeals
In the second, and concluding post in this series on camera trap noise, I look for “squeals” from the camera in the ultrasonic frequency range. I will describe some inexpensive hardware and software tools that I used to extend my hearing and to test several trail camera models we have used.
In the meantime, if you have experienced these, or any other types of noise from your trail cameras, please let me know if the comments below.
References:
Meek PD, Ballard G-A, Fleming PJS, Schaefer M, Williams W, Falzon G (2014) Camera Traps Can Be Heard and Seen by Animals. PLoS ONE 9(10): e110832. : A terrific paper covering both sounds and light produced by trail cameras, and including sensitivity of different species to sound and light frequencies.
This is great, I often wondered what exactly the animals were hearing from the camera. The video and audio of the filter moving is great! I’m sure knowing to consider a camera with separate sensors for daylight and darkness will probably help people out if they know they’re pursuing something particularly sensitive to the sound
Thanks for feedback! The two image-sensor solution is definitely a quieter way to do visible and IR photography. There are a set of “4-color” sensors available now that sense Red, Green, and Blue as well as (near) IR on separate channels. These sensors could be used in trail cameras to eliminate the IR filter without the cost of another separate sensor (and optics). I’m not aware of any cameras that do this, though.
Very useful and well put together information.
Thanks, Hal. Glad you found it useful.
II have moved to all duel sensor cameras finding that the IR filters have a high failure rate causing either off color daylight photos that cannot be corrected or black night photos.
Sorry to hear about IR filter failures. If you are interested in fixing, see recent post on “How (Some) Trail Cameras Fail”. The fix could be as easy as reflowing the solder on the wires to the IR filter. If you try, I’d be interested to know how you make out.
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Can you remove the IR filter Len from a camera ?
And will it work still ?
If you remove the IR filter completely, your camera will take night time photos/videos “correctly”, however daytime photos/videos will be pink (as in the cover photo for this post). On the other hand, if you cut one (or both) of the wires to the IR filter motor, and leave the IR filter engaged, the camera will take daytime photos/videos correctly, but night time photos and videos will be very dim (If the IR filter isn’t in the right state (i.e. if it’s disengaged) you can use a pin to “click” it into the engaged position).
If you are into the camera to do either of these minor surgeries, you should consider first trying to “reflow” the solder on the two leads connecting the IR filter motor to the PCB. This requires a soldering iron, and a little patience. For me, it also requires a pair of strong reading glasses so that I can see the point at which the solder on the pad melts completely.
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Do you have any night photos from a cam that have had the wires to the filter cut?
Well, not technically. I’ve never cut the wires. However, you are probably asking two questions: 1) do you have any daylight pictures where the IR filter is (erroneously) disengaged (out of the optical path); and/or 2) do you have any night time pictures where the IR filter is (erroneously) engaged?
On one, yes. We have photos from early Lift2’s in which the IR filter became unreliable, with the result that it was always engaged. Night time photos were fine, but daytime photos were red-tinged, as in a pink panther featured as the cover shot of How (some) Trail Cameras Fail
One two, not really. But if we did, they would look like this: in the dead of night, they would be very, very dim and black and white, since the IR filter is blocking out the IR flash (the only light available). In twilight, the image might be brighter (from available sunlight), but would still be black and white, as the camera is processing the image as a black-and-white image based on the low light.
I also helped someone fix a camera in which the motor wires were reversed — so all of his daytime photos were pink, and all of his night time photos were black 🙁
When I converted a Browning Recon Force Advantage over to white flash, as in IR to White Flash Trail Camera Conversion, I did some experiments where I either engaged or disengaged the IR filter during white-flash-illuminated night photos (this was after I hacked the firmware so it processed these images in color, vs. black and white). I thought the color balance with the IR filter engaged (same as daytime sunlit shots) was a little better than without.
Let me know if I missed your (underlying) question.
I was wondering just how bad the night time pics were if the filter was still in place. If you could still make things out it might be worth getting rid of the click. I have a tactacam sk that has spooked several deer.
Thanks
Oops — my bad — I forgot to look at the name of the post you commented on.
It’s definitely the case that the IR filter motor “click” spooks some animals.
Unfortunately, the IR filter effectively blocks almost all of the IR LED light, so I think the night photos/videos would be unusable.
There are cameras that solve this problem with two image sensors — one with an IR filter, and one without. They use IR filter sensor for daylight photos/videos and the one without at night. Browning makes one, as does Bushnell and Reconyx.
I’ve contemplated a firmware fix which would work like this: the firmware would figure out when dawn and dusk happen (I think many cameras already do this to make sure that timelapse mode is only active during daylight hours). At dawn and dusk every day, the firmware would wake the camera up and switch the IR filter to the right position in anticipation of a possible trigger later that day/night. This would still cause a click, but would almost certainly happen when there was no animal to hear it. When it was time to take a photo/video, the IR filter would already be in the right state, so no click. Waking the camera up twice a day to make the switch would consume a little more power, but not significantly more. I’ll add this “Smart IR Filter Motor” mode to my list of potential firmware hacks.
-bob
Yes that firmware would be a lot better. I was aware of the dual lens cams. I have went to all cell cams and looked the web far and wide for a cell cam with dual lens,trailcampro said no one makes one and hadn’t heard of anyone coming out with one. I luckily found one just after asking you about cutting the wires to the filter. I have one on order and hope it solves the problem. Sounds to good to be true really, dual lens,no flash,.4 second trigger,sends bigger pics, good data plans and reasonably priced
Ahh — I see. The requirement for cellular connectivity does add a wrinkle. Good luck with the model you found. If it works well for you, would be interested in hearing more.
Ok
Browning has a firmware update to fix the clicking noise at the beginning of videos. Does anybody know how they do it? I wonder if the firmware fix is as Bob Zak describes above or does it chop off the first half second of every video? I make You Tube wildlife videos and the clicking is annoying and time consuming to remove but I also do not want to lose a half second of every video clip.
I’m not sure that the “clicking” noise (sometimes) caused by the IR filter motor, and the “clicking” at the start of videos are the same. More likely, the apparent clicking that the Browning firmware fixes is an electronic artifact caused by not setting up the audio processing pipeline early enough. In all the firmware I’ve looked at, the IR filter motor is done moving when the video starts (actuation of the IR filter is done in parallel with the setup of the image sensors). I would go ahead and use this new firmware. If you have two cameras, you can upgrade one, and see if it triggers any differently than one you don’t upgrade in a controlled experiment where both cameras cover the same event.