All about... Trail Cameras
- PIR sensor
- Image resolution
- Wireless functionality
- Flash type
- Hybrid function
History of the camera trap
Over the past decades, the use of camera traps have been around for over 100 years and has increased enormously, for countless purposes. The invention started with an American congressman, George Shiras III, a pioneer in nature photography. He imitated a hunting technique of the Ojibwa tribe called "jacklighting". This involved the hunter placing a pan of fire in the front of the canoe, sitting in the back, and waiting patiently until the animal got close to the fire, stiffened up so the hunter had a clear view of the animal. Shiras replaced the fire and gun with a paraffin lamp, tripwire and a camera, resulting in a beautiful collection of photographs of wild, cryptic animals; published in 'National Geographic' (ed.1906). Over the years, the complex and heavy camera of that day evolved into the compact and sophisticated camera traps of today.
George Shiras III (front) and his assistant John Hammer (back) aboard their equipped canoe, Michigan, 1893 (Shiras 1906)
Camera traps only take pictures if there is actual activity in front of the camera. For this they depend on a so-called passive infrared (PIR) sensor. This advanced sensor activates the camera when it detects a source of heat that is moving. Camera traps therefore do not react to movement alone (i.e. not to a moving branch or a falling leaf), but only if the moving object is warmer or colder than its immediate surroundings. This means that the PIR sensor actually determines how a trailcamera works and is perhaps the most important part of a camera trap. Most manufacturers are not transparent about the exact working of the PIR sensor they use. By looking closely at a sensor's performance, such as response time (the time between detecting the moving heat source and actually starting to record), recovery time (the time between two consecutive triggers) and detection distance and angle (the distance and maximum angle at which the moving heat source is detected), you can get a good idea of how it works. A fast reaction and recovery time increases the chance that a fast moving animal is still registered in the middle of the image field (and therefore you will not see only a tail in the image, or even worse, a blank image without an animal).
PIR sensors consist of two components, a pyro-electric sensor (A) and one or more Fresnel lenses (B). The pyro-electric sensor consists of two elements that absorb infrared radiation and thus detect the difference in heat. The sensor does not pass through objects, so an open landscape provides a larger detection zone. As soon as a difference in thermal radiation is detected between the two elements, the pyro-electric sensor sends a signal to the camera to take a picture. The Fresnel lenses ensure that the infrared radiation within a detection zone is picked up cleanly by the pyro-electric sensors. The quality of the sensor and the design of the Fresnel lens varies between trailcameras and therefore some cameras are more sensitive than others.
The image below shows the interaction between the detection zones of a PIR (red) and motion sensor (1-6 faces) on a Reconyx HyperFire 1 trailcamera. The PIR sensor only sends a signal to the camera when an animal is in the PIR detection zone, a difference in temperature is detected, and the animal enters or leaves one of the surfaces. The deer (top left) is therefore not detected by the camera trap (modified image taken from Reconyx).
One of the first things that often comes to mind when comparing camera traps is the number of megapixels, thinking 'the more megapixels the better the image quality'. Camera trap manufacturers cleverly capitalise on this by interpolating the number of megapixels (see box below) and then advertising these interpolated megapixel values. However, the true sensor resolution is rarely reported, while in fact this says much more about the image quality of the camera.
A similar marketing trick is used for video resolution. Nowadays there are already trailcameras on the market with a 4K Ultra HD video resolution. This sounds very good, but in reality, this resolution is only achieved at a frame rate of 15 frames per second (fps), while Full HD cameras usually have a frame rate of 30 or even 60. The number of frames per second says a lot about the quality of the video image. A higher number of megapixels or a higher resolution of the video images does not always equate to better images. The best advice is to base your opinion on actual images.
Interpolation is the derivation of new data points within the range of a set of known discrete data points under the assumption of some relationship between them. Concretely, in the case of trailcameras and megapixels, this means that the software in the camera tries to make, for example, four pixels out of one actually measured pixel. The colour of these four new pixels is determined on the basis of the colour of the immediately surrounding measured pixels. Although there are forms of good interpolation, it is a myth that this increases image quality. Interpolation remains an adaptation of the actual measured image. In addition, interpolation is often accompanied by more digital noise and colour shifting. It also leads to more data storage and battery consumption.
Adjustable image resolution
With many camera traps, the image resolution is adjustable for both photo and video. By adjusting the resolution to your desired target, you can make efficient use of the battery life and storage capacity of your camera. The highest possible resolution may be unnecessary, for example, if you only want to demonstrate the presence of a relatively easy identifiable species. You are also aware of the fact that a higher image resolution does not always result in sharper and better pictures (see text above). In fact, a higher image resolution often results in a slower shutter speed, with the possible result that a moving animal will appear blurred on the photo. A higher image resolution can be especially useful when observing small, less identifiable species.
With a timelapse function, the camera trap takes photos or videos at a fixed interval. Examples include the process of a building construction (see example), or the monitoring of breeding waterfowl, or the monitoring of nature restoration measures (see example). The timelapse function can also be used for a completely different purpose, where it is less prominent, but nevertheless very useful. With a timelapse, you can ensure that the data is still usable if the trailcamera is disturbed (e.g. by an animal, dead batteries, full SD card, etc.). By setting up a timelapse beforehand, you can refer back to an exact moment in time when the camera trap was still undisturbed. You know exactly from when to when the camera was functioning well. For this, you can set the timelapse so that, for example, a picture is taken every 12 or 24 hours. However, not every trailcamera has a timelapse functionality, and the settings differ from model to model. Pay attention to this if you plan to use the timelapse functionality a lot and ask us for advice if this is your main goal.
With an internal viewer, you can evaluate images directly in the field and see exactly how the camera trap is positioned. This makes the installation of a camera trap much easier. As soon as a trailcamera has an internal viewer, it is important to pay attention to the position of the internal viewer inside the camera. It is possible that the viewer is not suitable to assist in aiming the camera, because the lens of the camera is turned away when you want to look at the viewer live (see below). Of course, any model that has an internal viewer can be used to look back at the images that have been taken!
Three camera trap models, two of which have an internal viewer (the middle and right model). With the model in the middle you see that you have to open the front of the trailcamera (incl. camera lens) to observe the viewer, which means that your viewer cannot be used directly (i.e. live) to aim the camera. The model on the right takes this into account and gives you a live view of what the camera sees.
Whereas up until a few years ago, all camera traps were stand-alone devices that stored all captured images locally on a memory card, today we are seeing more and more forms of wireless connectivity in camera traps. Here, we explain which forms of communication are now available on the market and the main differences between these wireless options. In fact, we can distinguish 4 types of camera traps:
Camera traps without a wireless functionality
These are the traditional camera traps that function completely autonomously and store the images locally on a memory card. With this type of trailcamera, you always need to physically visit the camera and read out the memory card in a suitable device. These cameras do not have any wireless functionality.
Camera traps with Bluetooth functionality
Camera traps with Bluetooth functionality allow the owner to connect to the camera from a short distance (up to about 20-25 metres in an open line of sight), to read the captured images or to adjust settings. This always works with an app that needs to be installed on a phone or tablet (suitable for IOS and Android). It is therefore necessary that you have a smartphone or tablet with Bluetooth functionality. In most cases, the images that are downloaded to the app are a reduced version of the original. The original file is still stored locally on the memory card inside the camera. The moment you start downloading the images from the camera, the connection will switch to a wifi 'hotspot' that is put in the air by the camera itself. This is why these types of trailcameras are often referred to as having "Bluetooth / WiFi functionality". Although this is correct in principle, it is important to realise that it does not mean that you can also use this type of camera trap to make a connection between your camera and your own existing WiFi network at your home. For that you need another type of camera trap (see below). Camera traps with Bluetooth functionality are particularly interesting when you place the camera in a location that is difficult to reach (such as at the top of a tree near a bird's nest, high up in the gutter, or deep in dense bushes), or that you want to disturb as little as possible (such as the nest of a meadow bird or the lodge of a beaver). It is also fun to place such a camera in your own garden, so that you can watch the shots from your sofa just within the specified range. Some models, such as the Browning Defender cameras, also offer the option of watching the camera live, as soon as the connection is established. This can be fun when the camera is in the garden. When you see something beautiful appear in front of the camera, you can immediately follow along. Camera traps with Bluetooth functionality:
Camera traps with WiFi functionality
Camera traps with WiFi functionality are camera traps that are able to connect to the existing WiFi network of your own internet provider. There are currently very few cameras that offer this functionality. In general, cameras with this type of WiFi functionality also have the Bluetooth function discussed above. With this type of WiFi functionality, it is possible to download the recorded images to a special app on your phone or tablet anywhere in the world (with an internet connection), without the need for a SIM card - and therefore without extra costs. Of course, it is a prerequisite that the camera is within the range of your own existing WiFi network (for example, in your garden or holiday home). An additional advantage of the WiFi functionality is that, in the event of theft of your camera, you will still be able to access all the images because they will have been automatically sent to the app on your phone or tablet. Camera traps with WiFi functionality:
Camera traps with sim-card functionality
Camera traps that can be equipped with a SIM card, which may or may not be already integrated in the camera by the manufacturer, make it possible to transmit camera images directly to an e-mail address or cloud server. So you know immediately when something has come close to your trailcamera. With this SIM card functionality, you can receive images at unlimited distance and does not restrict you to locations with an existing WiFi network. The only requirement is that there is coverage from the mobile network of the respective SIM card provider. In contrast to the Bluetooth or WiFi functionality, there are always additional costs associated with the use of this type of camera. It does not make much difference which provider you choose and whether you want to use the camera in the Netherlands or elsewhere in the EU. The costs between the providers are almost the same and the costs are the same throughout the EU due to net neutrality. In terms of costs, it mainly depends on whether you make use of a subscription, benefit bundles, or whether you simply pay for your usage directly from the prepaid credit. In any case, sending one photo (usually a reduced version of the original) costs about 1 cent. However, if you choose to send photos in larger resolution or even in real format, or if you choose to send videos (assuming the camera is suitable for this), then the data consumption is much higher, and therefore the costs aswell. To give an example, let's take the provider KPN. KPN's prepaid rates can be found here. At the time of writing, the standard rate for data is 15 cents per MB. Forwarding 1 picture is about 50 KB, so you can send about 20 pictures for 15 cents. However, if you send a picture in real size, this can quickly result in a file of 3-5 MB. This means that each photo you send will cost you about 45-75 cents. If you send a video of 10 MB, it will cost you €1.50. In that case, it is not at all attractive to use the standard prepaid credit, but it is much wiser to use monthly bundles or a subscription. For example, KPN currently has a monthly bundle with 200 MB for € 6. The rate per MB is 3 cents, and for sending 1 video of 10 MB you pay 30 cents. You can then send 20 videos of 10 MB per month with such a bundle. If that is not enough, you can take a monthly bundle of 1 GB for € 10. In that case the rate per MB is about 1 cent, so forwarding 1 video of 10 MB will only cost you 10 cents. You can then send approximately 100 films per month. If that is still not enough, then it becomes more attractive to take out a Sim Only subscription and compare the different providers carefully.
Camera traps with a SIM card that can immediately transmit recordings anywhere and at any time are often used to monitor game traps, so that the time that animals are in the trap can be reduced and the whole trapping team only needs to be called in when the desired species is caught. This functionality also works well for monitoring remote locations or to minimise disruption to the location in question. Think, for example, of a bird's nest. In addition, such cameras are an excellent alternative to 'traditional' security cameras, as they are waterproof and do not require a power or network connection. This makes them as mobile as possible and remote areas or objects can be efficiently secured and you always receive the evidence on your phone, tablet, or computer within 10-15 seconds after making a recording. Even if the camera is stolen or disturbed, the first images are often already sent to the owner, so they can take action!
Most camera traps with a SIM card functionality are supplied without a SIM card. This is because most cameras can be equipped with a SIM card of your choice, and you as a customer are free to do so. However, each camera must be configured to work with the SIM card that is inserted. Therefore we offer you the possibility to choose to add a prepaid SIM card of KPN to your order. We then set up your wildlife camera completely for use with this SIM card and can even enter the receiving e-mail addresses already. This way, you can place the camera at the desired location immediately after receipt and you don't have to set it up anymore! The settings themselves are quite precise and not always easy, and therefore we recommend that you check this option if you are going to order a camera trap with SIM card functionality. If you then indicate in the comments field when placing your order to which e-mail address(es) the images should be sent, we will ensure that this data is already entered inside the camera. Naturally, you can easily modify these details in the trailcamera at any time. In case you have purchased a camera trap with simcard functionality elsewhere, but you cannot get it to work, we also offer the possibility to do this with us on a "no cure, no pay" basis. If we are successful in setting up the camera and sending images, you will pay € 50,-, including returning the camera back to you. If we also fail to get the camera working, you pay nothing and we will send the camera back to you. If you want to make use of this option, always send us a request by e-mail to firstname.lastname@example.org first. Camera traps with SIM card functionality:
- Snyper General 3G SIM WIRELESS
- Snyper Commander 4G SIM WIRELESS
- Bolyguard MG984G-36M 4G SIM WIRELESS
- Bolyguard BG668-E36WG 4K 4G SIM WIRELESS
- Spypoint Link Micro LTE 4G SIM WIRELESS
Type of flash
A crucial part of any wildlife camera is the flash. Today's wildlife cameras can be roughly divided into three different flash types: a white flash, a visible infrared flash ('low glow', ~850 nm), and an invisible infrared flash ('no glow', ~940 nm).
A comparison between the three different types of flash mechanisms (White LED, Low glow, and No Glow; from left to right) installed in today's wildlife cameras (images from Wearn and Glover-Kapfer, 2017).
In the past, camera traps were all equipped with a white flash (like regular cameras), with the advantage of providing sharp and colourful images at night. It makes identifying smaller (mammals) animals and individuals much easier. These kind of camera traps are great for accurate and fast inventories, plus the application of the capture-recapture method (a method to estimate absolute abundance). A disadvantage, however, is that it is very conspicuous and can therefore disrupt the natural behaviour of the animals. Also, this type of flash is much more likely to be noticed by people.
Visible infrared flash (‘low glow’, ~850 nm)
camera traps equipped with a visible infrared flash are much less disruptive than the white flash. However, the visible infrared flash produces night images in black and white, which makes identifying individuals and small (mammal) animals quite difficult. Some features can even disappear because of the IR flash (see picture below). Trailcameras with a visible infrared flash show a low glow of the red LEDs, when looking straight at the camera. It is generally accepted that this red light is not disturbing to animals. The visible infrared flash generally has a slightly stronger exposure and a wider flash range.
Invisible infrared flash (‘no glow’, ~940 nm)
Camera traps equipped with an invisible infrared flash are not easily noticed, especially by people. An excellent feature for a security camera and a good consideration when there is a risk of theft or vandalism. The night images are in black and white, which makes identifying individuals and small (mammal) animals quite difficult. Some features can even disappear due to the IR flash (see picture below of the same cat).
Both pictures show the same cat, but at a different time of day (night vs. day). On the right photo, due to the IR flash, the orange spots are not visible, so it can be perceived as a different individual.
It is not just the flash, but also the flash range that matters. A larger range makes it easier to observe animals at a distance. As the flash range decreases, there is a greater chance that the animal will be less visible at a distance and you will therefore get a less accurate observation. On the other hand, if the flash is too strong, it may result in an overexposed photo or video. For example, when an animal moves close to the camera. Please bear this in mind when positioning your trailcamera. In order to take over- or under-exposure into account with varying camera setups, some camera traps offer the option to adjust the flash range.
With the majority of today's camera traps, you can preset to take photos or videos. However, not simultaneously. Camera traps that are equipped with a so-called hybrid function are able to take photos and videos simultaneously. This works as follows: when the cameratrap is triggered by a moving heat source, first one or more photos are taken (depending on the settings and the possibilities of the game camera concerned), followed by a video. This is a very nice functionality, but be aware there is always time needed for the camera to switch between photo and video mode. This time between photo and video differs depending on the speed of the camera, but as a result it can be possible that the animal is already out of the picture as soon as the video mode starts. Please bear this in mind when using this feature, so that you do not unnecessarily waste battery and storage capacity. This feature is useful when you want to obtain both still images and video from the same snapshot. It is also useful for wireless models, as videos cannot always be transmitted properly due to their size. With a forwarded photo, you can stay well informed of what is happening in front of the trailcamera while you can later review the videos on the memory card.
Here is a summary of the differences between photo and video mode. Perhaps this can help you make the right choice for your application.