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.

 

Chapter 3 - Illumination

Advantages/Disadvantages of available flash options

Modern trail cameras use light-emitting diodes (LEDs) to provide illumination for nighttime photography. The most common option is a flash array using infrared LEDs ranging from 850 nanometers (red glow) up to 930 nanometers (no glow). These infrared flash arrays produce very little visible light (if any), but are only capable of capturing black & white images.  Although rare, there are trail cameras that capture full color photos and videos using white LEDs similar to those found in LED flashlights. As expected, these cameras produce a tremendous amount of visible light and are often associated with influencing animal behavior.

Visible Light?  Red Glow vs Low Glow vs No Glow

So which of the above options is best? How identifiable is each?  Well, that depends on you..... literally.  Every animal (humans included) can detect different levels of infrared light. Just as some humans are colorblind, some humans are predisposed to detect a higher nanometer level of infrared light.  To determine the flash category of each camera, we place the unit in a pitch-black room and have numerous staff members stare directly at the camera as it snaps photos. Some units are universally visible to everyone and classified accordingly as "Red Glow."  Conversely, some units are not visible to anyone and are designated "No Glow."  Until recently, these were the only two categories we used.  However, we felt it necessary to create an additional category for those units that, although advertised as "No Glow," could still be identified by some observers. Having said all this, nearly all modern IR flash trail cameras are discreet and can only be identified if looking directly at them.

So which flash type is best for your application? Generally speaking, red glow units provide better illumination, resolution and flash range than no glow units. No glow units are less prone to be noticed, but often produce lower quality photos. However, it's important to note that a no glow unit was the overall winner of our Flash Range contest the last two years. Here are some reasons why you might pick one over the other.

Red Glow

Red glow trail cameras are typically used for general scouting where discretion is not a concern.  Because they reach out farther, they're ideal candidates for larger areas such as food plots, fields, backyards and parking areas. The faint red light they produce is also less discernable in urban areas.

No Glow

No Glow trail cameras are ideal for security applications and instances where spooking animals is a concern.  They are especially useful in tight quarters.  I always use no glow cameras when patterning specific animals.  As I identify their travel patterns from food sources to bedding areas, I can place cameras in close proximity without disrupting their behavior. In security settings, they can be mounted close enough to record useable video without being discovered.

White LED

White LED cameras are the only option for recording color images and videos at night. Big cat researchers use these models to identify individual cats by the color of their spots. In a security setting, the near blinding light can also work as a deterrent.

 

 

Chapter 4 - Power supply

This chapter is worthy of an entire book.  Having said that, I'll try to keep this as brief as possible and provide links to more in-depth content where applicable.

Trail Camera Power Options

Batteries

The beauty of a trail camera is its simplicity and ease of installation. Insert batteries and a memory card, and you can hang it anywhere you please.  If that location isn't suitable, you can move it in a matter of minutes, with no wires or extra equipment.  For this reason, I always prefer batteries as my primary power source.  Trail camera technology has evolved to a point where cameras can last in the field for years, compared to the few weeks when they were first introduced.  However, if you choose batteries, you still have additional decisions to make.  Batteries use several different chemistries and are available either as rechargeable or one-time use (disposable). 

Let's look at the pros & cons of each:

 

Alkaline

Alkaline batteries are widely available and the least expensive (50 cents/cell) of all options. The best alkaline cells provide about 1600mAh capacity, which is on the low end of available options. While they are not affected by hot temperatures, they are crippled by temperatures below freezing and often shut down.  This makes the use of trail cameras during hunting season a real problem. Telltale signs are black photos at night and periods of time where no photos are captured.  Additionally, alkaline batteries are notorious for leaking acid and destroying the device they were installed in.  Finally, they end up in the landfill after one use.

 

Nimh Rechargeable

The best Nickel-Metal Hydride Batteries provide 2500mAh and have a proven track record of reliability.  However, NiMH batteries do have shortcomings.  While the typical AA cell provides 1.5 volts of DC power, NiMH cells only provide 1.2 volts. Most trail cameras use (8) AA cells for an aggregate of 12 volts.  Using NiMH cells in this scenario would only produce 9.6 volts, and that is insufficient to power some trail cameras.  Additionally, most NiMH cells begin to self-discharge the instant they are removed from the charger.  Cells can not be stored indefinitely and be expected to have the required capacity.  NiMH cells handle high current demands very well and also perform well in cold temperatures.  Unfortunately, Temperatures above 80 degrees greatly diminish their capacity. NiMH cells run about $4/cell.

 

Lithium (one-time use/disposable)

Lithium cells became widely available 10 years ago and immediately took over as the "Go To" option for trail cameras.  The cells provide 1.6volts and have about twice the capacity of the best alkaline cells.  The usage curve is very flat, meaning they provide very consistent voltage throughout most of their lifecycle.  Additionally, they are about half the weight of alkaline or NiMH cells, which has a significant impact when trekking into remote areas. Unfortunately, their cost has risen to the point of impracticality - especially when they are headed to the landfill after just one use.

 

Lithium-Ion Rechargeable

Lithium-ion rechargeable batteries have recently become cost-effective ($5/cell) and practical to use.  While Li-ion cells don't have quite the capacity of their one-time use cousins, they still have about 25% more capacity than the best alkaline cells.  Additionally, they have a very low self-discharge rate, and their usage curve is absolutely flat throughout their entire lifecycle.  The native voltage of Li-ion cells is 3.7 volts.  Each cell has voltage reduction circuitry that regulates exactly 1.5 volts at the tip for the entire charge cycle.  The Li-ion chemistry is not adversely affected by temperature swings, and the Li-ion cells are roughly half the weight of alkaline or NiMH cells.  Li-Ion batteries will power most non-cellular cameras for more than a year and most cellular cameras for an entire hunting season.  Finally, they can be charged hundreds of times and usually pay for themselves after the second charge. You can find Li-Ion options here.

An in-depth explanation of battery options & how they work can be found here.

 

Solar Panels

Solar panels can be a great option to extend the life of your trail camera. Unfortunately, not all solar panels are created equally, and not all work in the same way. Sophisticated (expensive) panels are divided into multiple, independent power-producing sections. If one section becomes obstructed, the others continue to provide power.  Inexpensive panels cease to produce power if even a small section is obstructed.  Ideally, a solar panel would power your trail camera and charge the internal batteries with any excess power.  In the absence of light, the internal batteries would power the camera until the solar panel generated power again. Thankfully, some units operate this way.  However, many do not. Many cameras we test connect to a solar panel via their 12-volt external power jack.  The camera analyzes the voltage from both the battery bank and the solar panel and uses the source with the highest voltage. Depending on the batteries installed, this can result in inefficient use of one or both power sources.  Additionally, no camera can charge the internal AA batteries via the 12-volt jack except some that have a rechargeable cartridge with a plug on the bottom of the battery or an internal battery. Finally, the cable connecting the solar panel (unless armored) is a prime chewing target for squirrels and other rodents. Capabilities vary by manufacturer. Contact Trailcampro for clarification.

 

Solar Packs

Solar packs are solar panels with a battery bank incorporated into the housing. Solar packs charge their internal batteries regardless of input from the camera to which they are connected.  In most cases, this allows the camera to rely on the solar pack as its primary power source and only call on the camera's internal batteries in rare circumstances. Although Solar Packs are vulnerable to the same squirrel damage, they offer a much more compatible power option than solar panels alone.

 

Chapter 5 - Photo storage & Memory Cards

Most people wouldn't think there's much to talk about on this subject. Your camera stores photos on a memory card. You remove the card to view those photos.  Seems simple, right?  I wish it were. We'll delve into all the details, but first, let's discuss brands, quality, and the class of cards.

We've sold nearly a million memory cards over the last 20 years, and there is no debate. SanDisk is the undisputed leader. They are universally compatible with all devices, and their failure rate is nonexistent. We've sold less expensive cards and regretted it. Our institutional research clients venture into remote areas and leave cameras unattended for months.. Any amount of lost data can't be justified by saving a dollar or two.  Imagine losing months of data on a near-extinct species?  We've exclusively sold SanDisk cards since 2015 and haven't had an issue since.

Class of Cards

Most trail cameras operate perfectly with standard speed cards.  Expensive, high-speed cards are not only a waste of money, but some are also incompatible with certain camera brands. One exception is Tactacam, which recommends using a U3 card with a minimum transfer speed of 90 Mbps.

Why some cameras are better (worse)

When I run cameras, I want to enter an area, swap memory cards, and exit as quickly as possible. I want to open the camera case, easily find the power switch, and turn the unit off. The memory card should be easily identifiable and also easy to replace. When the camera is powered back on, the screen should display the battery level and the number of images that can be captured.  Finally, the camera should start a countdown indicating when it will start taking pictures, or include a button to start the process.  If designed properly, this should take no more than 5 seconds. Unfortunately, not all cameras operate this easily. And without thorough research, most people won't discover this until they've already purchased the camera.

What to look for

The memory card slot should be conspicuous, and the presence (or absence) of a memory card should be obvious.  The camera pictured above clearly shows the location of the card slot, the orientation of the card, and the direction of insertion.  A portion of the inserted card extends below the case, allowing the user to easily identify and remove it.  This represents a "Best in Class" design.

 

What to Avoid

Unconventional Card Location/Orientation

With the vast majority of cameras, the memory card is inserted at the bottom of the case. Cards inserted into the camera pictured above are not only in an unconventional location, but they must also be inserted backwards, with the label facing away from the user. All SD cards have a notch at the bottom of the label side that aids in their removal.  In this case, the notch is inaccessible, making removal difficult, especially with gloved hands.

 

Micro SD Cards

Some devices are so small, they require the use of a Micro SD card. Trail cameras are not that small.  Micro SD cards are difficult to handle and easy to lose.  Avoid any camera that uses a Micro SD card.

 

Internal Memory Only Units

The cellular unit pictured above has no programming screen or buttons & no removable memory.  It simply has an on/off switch. Everything must be programmed through the app while an active paid subscription is in place.  Full-resolution images are only available when the camera is connected to a PC via a USB cable, and HD images must be downloaded at an additional cost. A rep for a similar camera (not this manufacturer) told us, "If this camera isn't making us $15/month, we don't want it to work."  The industry has transitioned to a subscription-based profit model, but I would still opt for a camera that functions without the need for a subscription, while they still exist.

 

Memory Card Readers

My eyes are 60 years old.  If I need to review photos in the field, it's gonna be with the biggest laptop I can find.  However, it's not practical to carry a laptop in my hunting pack. If the route to my hunting stand takes me by a camera or two, I'll swap cards and review photos with a card reader while up in a tree.  It helps pass the time & could provide valuable scouting info for my next hunt.