At some point, every trail camera user in the world has had an SD card full of false triggers. From experience, I can tell you it's painstakingly frustrating scrolling through 10,000 photos of nothing just in case there might be a single "real" photo buried somewhere in between. It's that same fear of missing out that bites me every fall but that's a whole different topic.
So what is the cause of "blank photos" or what we refer to as false triggers? The cause can range from a multitude of things...It could be product failure. It could be a settings error in how the camera was programmed. It could be how the camera was set up in relation to the surrounding environment.
We'll break down each scenario to provide a better understanding of each cause but before we do that it's extremely important for trail camera users to understand how cameras are triggered.
How Trail Cameras Are Triggered
Simply put, trail cameras are triggered by a detected change of infrared radiation in the environment that is being monitored by the camera's PIR sensor. This change in IR radiation can happen for a multitude of reasons. An element in the PIR could be burned out, an object could be passing through the detection area, or something as simple as the sun glaring on grass blowing in the wind. For a much more technical break down check out our article "An In-Depth Look: How Trail Camera Detection Circuits Work".
As mentioned, reading the trail camera detection article will enlighten and add more context around this scenario. False triggers/blank photos as a result of product failure are caused by a faulty PIR sensor or what we refer to as a run-away PIR. When an element inside the sensor fails, it mimics a constant difference in the IR radiation readings which triggers the camera. This is relatively common with trail cameras that operate with ultra-sensitive PIR sensors manipulated by voltage and circuitry. As a trail camera user, if you think you have a camera with a faulty PIR sensor, it is extremely easy to test and verify with the steps below
-Program the camera to Photo mode
-Set trigger delay to a short time, less than 30 seconds
-Set the burst count to 1 photo
-Format the SD card so it has no photos on it
-Power the camera on to the operational mode
-Place the camera in a dead environment where it will be impossible to record any trigger events. You can set it up in a cabinet with the door closed, directly against a wall so the camera lens and PIR are facing the wall, inside a closet, etc.
-Let the camera run for 5 minutes or so
-When you retrieve the camera and view the photos there should only be a photo of when you set the camera down and picked the camera up. If there are several photos on the camera with a time difference matching the trigger delay the camera has a faulty PIR sensor.
Surprisingly, a lack of understanding of simple trail camera programming is somewhat common and often the cause of what people believe to be false triggers. There is only one thing to understand and double-check to verify the camera is not programmed incorrectly and that is Time Lapse mode. Time-Lapse mode in a trail camera will traditionally operate the camera to take a photo at set time intervals, leaving the PIR sensor inactive to trigger the camera. So if one had a camera "accidentally" programmed in Time Lapse mode at a short time interval like 15 seconds it would appear that the camera had a runaway PIR when in reality the camera was simply programmed incorrectly. With that said if you are experiencing false triggers at specific time intervals between photos, this should be the first thing to check and troubleshoot.
The video above gives a quick rundown on troubleshooting and a couple of causes of false triggers.
Purely self-inflicted and one of the most frustrating things trail camera users can go through is thousands of false triggers from a branch or grass moving around in the detection area. With wind storms and other weather events false triggers that are environment-induced are next to impossible to totally eliminate but there are some things trail camera users can do to significantly reduce them. Simply clearing any branches, weeds, grass, and other debris in the camera's detection area that has the potential to be easily moved by the wind should be removed. Aiming or positioning your cameras where the field of view and detection area will receive less sunlight also helps the cause. If you are ever wondering if your false triggers are a result of the environment and weather, just scrolling through the photos at a fast pace will show you any object with movement. This concept is almost like stitching each still frame together to create a video.
All in all, truly understanding PIR sensors, trail camera detection circuits, and how they work will prove to be invaluable when trying to pinpoint the cause of blank photos. While this article should provide some insight and baseline knowledge of different causes, be sure to check out the article mentioned above. For more content from educational trail camera content to the whitetail, hunting strategies be sure to check out our podcast Trail Cam Radio and YouTube channel.