Trail Camera Anatomy

Achieve Better Results By Knowing Exactly How Your Camera Works

Chapter 1 - Motion Sensors

Modern trail cameras detect motion using a Passive Infra-Red (PIR) detection circuit. Unlike the alarm system lasers you see in movies, these PIR systems use a Fresnel lens to capture energy created by a combination of movement and heat.  The Fresnel lens concentrates the energy and transfers it to a PIR sensor mounted to your trail camera's circuit board. This action starts the triggering process.

Notice I said a combination of motion and heat.  Motion alone will not work.  Your camera must detect something hotter than the surrounding air moving through space.  The greater the temperature differential between the moving object and the surrounding air, the stronger the signal. This is why a buck moving through the woods during the cold Fall hunting season is much easier to detect than a rabbit on a hot Summer's day.

"My camera is defective.  I walked right up to it and it never captured a photo."

The technology used in PIR detection circuits is amazing, but it's not perfect. There are many types of Fresnel lenses, but most create a series of detection lines emanating outward from the camera. To trigger the camera, an animal must cross somewhat perpendicularly through at least two (2) of these lines in relatively quick succession.  If an animal walks directly towards or away from the camera and touches only one line, no photo is triggered.

 

This is why it's ideal to aim a camera covering a game trail at a 45-degree angle, cutting across the trail.  Most animals following the trail will trigger the camera multiple times, and you'll cover more area than if it were aimed perpendicular to the anticipated route. You can learn more about maximizing your photo opportunities on our How to Aim Your Trail Camera page.

 

Motion Detection Tips

Do:

• Aim your camera in a Northerly direction
• Position your camera at the same height as the core body height of the target species
• Aim your camera parallel to the lay of the land for maximum detection range
• Position your camera aiming perpendicular to the anticipated path of travel
• Attach your camera to a sturdy object unlikely to move with the wind
• Remove all loose debris that could produce false triggers

Don't:

• Aim your camera in the direction of the rising or setting sun
• Aim your camera at tall grass or areas with leaf litter
• Aim your camera through any type of glass (cameras can't detect motion through glass)
• Mount your camera high, aiming down (unless you intend to greatly reduce detection range)
• Attach your camera to a flimsy structure or a small tree
• Wedge sticks behind your camera to aim up or down

 

Chapter 2 - Lens and Image Sensor

 

 

Your camera's lens and image sensor work together to capture photos when the camera is triggered.  The lens serves as a weather-tight window to protect the image sensor from the elements.  Many are constructed of cheap plastic and are prone to scratching and oxidation. Over time, these inexpensive lenses will produce cloudy and distorted images. However, some plastic lenses can be restored using one drop of auto polish and a microfiber cloth.

The best cameras use polished glass lenses.  

 

Image sensor

 

Your camera's image sensor is mounted to the circuit board, protected by the waterproof lens.  The sensor converts light into electrical signals that can be processed into a digital image. It uses millions of tiny light-sensitive pixels that capture incoming light. These pixels generate electrical charges, which are then converted into digital data by the camera's processor, creating the final image.

The Megapixel Myth

The industry is fixated on megapixels and uses the term aggressively in advertising.  The average consumer naturally thinks "More is better," and often falls prey.  In reality, most manufacturers install a 4-megapixel sensor and use a process called interpolation to artificially increase the image to 24, 36, or even 48 megapixels.  During the interpolation process, your camera's software uses an algorithm to guess the color and intensity of new pixels added to the photo. However, it's crucial to understand that interpolation doesn't add new information or detail to the image. Instead, it estimates the values of new pixels based on the surrounding existing pixels. This means that while the image will become larger in terms of pixel count and file size, the sharpness and detail may not significantly improve, and can even suffer depending on the interpolation method and the extent of upscaling.

 

"Interpolation does little to increase clarity or resolution, but exponentially increases file size.  The result is a marginally improved photo (if at all) that sacrifices your camera's speed and storage space."

 

With this in mind, we always program our cameras to capture photos at the native resolution of the installed image sensor (typically 4 megapixels).  After decades of testing, this resolution has proven more than adequate for scouting purposes.  Please note: Image sensors vary from manufacturer to manufacturer. Two different 4 megapixel sensors can produce drastically different photos.  We recommend closely examining photos before purchasing any camera.

 

What if 4 megapixels doesn't produce the resolution you require?

 

There are a few trail cameras with native 16-megapixel image sensors. Should you buy one?  The answer is it depends. A quality 16-megapixel sensor will capture better daytime photos, but nighttime photos will likely suffer. As the number of megapixels increases, the sensor's ability to gather light decreases. The result is diminished illumination and decreased flash range.  It truly is a trade-off.  Magazine-quality daytime photos come at the expense of compromised nighttime photos.

 

Can you have your cake and eat it too?

 

The Dual Sensor (DS) Trail Camera

 

To address the trade-off quandary, companies began manufacturing dual-sensor (DS) trail cameras. These new DS models incorporate a dedicated image sensor for daytime photos and a separate image sensor for nighttime shots. DS units typically have an 8 or 16 megapixel day sensor and a 1.3 megapixel image sensor optimized for night photography. The two separate sensors also eliminate the need for the IR filter (seen below) used in standard cameras. 

 

IR filter switching from day to night mode

 

In summary, your camera's image sensor and lens determine the quality and resolution of your photos.  These components can vary drastically from model to model.  Additionally, a camera's megapixel rating is absolutely not a good factor to base a purchasing decision.  Scrutinize numerous photos taken by any model you're considering and choose accordingly.