The term Bullet Camera comes from its resemblance to a rifle bullet. Generally long and tapered like a cylinder, it looks like an oversized ammo cartridge. Most bullet cameras come with a fixed 4mm lens that allows a 70 degree angle of view. This is the widest angle you can have without distorting the picture. A 4mm lens will allow you to see facial features out to about 35 feet. If infrared is included you can generally see 35 feet minimum with no external lighting, some can see up to 70 feet.
Some devices capture images in color which is best for daytime lighting. For nighttime viewing choosing an infrared camera, which captures images in black and white is better. Many of the products will display color during the day and automatically switch to black and white infrared viewing when light levels are low. Resolution levels for black and white are usually about 400 lines, any higher resolution and the benefits are minimal. For color, the higher resolution the better the picture. Used in closed circuit television applications, bullet cameras contain essentially the same electronic components as c-mount cameras but have been modified to fit in a weatherproof casing for outdoor use. You can see from the image that some models allow the housing to be removed for installation indoors. Mounting brackets are included with each item. They can be installed on the ceiling or the wall. Voltage is 12V DC. Power adaptors are included with every camera.
The advantage to a c-mount camera is that the lens can be changed. If you need to see further than 35 or 40 ft then you’ll need a c-mount camera with a special lens. C-Mount lenses are available from 4mm to 100mm. A 4mm lens provides facial detail and a 70 degree angle of view focused up to about 35 ft. An example of where you might use a fixed 4mm lens is in a small office, or at home to focus on your driveway.
A higher millimeter lens will provide further distance, but narrows the field of view. So, a 16mm lens would provide about a 15 to 20 degree angle of view at a focus distance of about 35 ft (or a 70 degree angle of view at about 140 feet). In general, a 8mm lens is like a 4mm lens zoomed in 2 times. Similarly, a 16mm lens is like the 4mm lens zoomed in 4 times.
Many times, the best option is to use a varifocal lens. This will allow you to vary the focus from 5 to 50mm. So when you install the camera you can fine tune the focal distance and angle of view. An example of where you might use a varifocal lens is outside (or inside) a large commercial building where you need more distance than 35 ft. and the varifocal lens will allow you to adjust the focal distance to your preference.
If you want to use cmount cameras outside, you must put them in an outdoor camera housing. CCTV lenses are available in two different lens mounts. “C-mount” lenses have a flange back distance of 17.5mm; “CS-mount” lenses have a flange back distance of 12.5mm. The flange back distance is the distance from the flange of the lens (beginning of the lens mount) to the focal plane. All of the C-Mount cameras we sell can be adjusted for installation of a CS-Mount lens as well as a C-Mount lens.
Maintenance of your CCTV system is vital to ensure the effectiveness of your security camera system. The type of maintenance required varies depending on whether you have an analog video system or a digital video system. The most common problem for analog systems is the degradation of the videotapes. All too often this problem isn’t recognized until a problem occurs and the tape is unusable. When a videotape degrades the picture becomes grainy and blurry – this can make it impossible to make out important details.
The effective life of a videotape depends on the time-lapse speed of the VCR. A general rule of thumb is to take the number 2000 and divide that by the speed of the recorder. For example, if the recorder is set to tape in 96-hour mode, then the videotape will start to degrade after only 20 uses. And the VCR itself should be overhauled every 10,000 hours. This is precisely why many business owners are switching to digital video recorders (DVR) instead of VCRs. Since digital video recorders have very few moving parts they require less maintenance than a VCR. Also when there is a problem with the DVR it is usually more evident. For example, the system will start crashing a lot or it will stop working altogether. Cameras can go bad over time as well. But again, these problems are usually fairly evident. Periodically take the time to review all of your cameras and make sure that the picture on each one is crisp and clear.
Experts say that the biggest problem with many security camera systems is that they are not well enough designed to begin with. Many times a business owner is so concerned with cost that they cut corners on their camera installation. As a result there may not be enough cameras used or they might not be the right kind of cameras or lenses. Your camera system should cover all of the vulnerable or important areas of your site. Don’t overextend the camera by using lenses with a field of view that is too wide. Test out your cameras and recording equipment to ensure that it is effective for identification – not just verification that someone is there. If nighttime or low light is an issue make sure your infrared cameras are up to the task. Take few moments to ensure that your camera system is designed and working properly today – you’ll be glad you did if you ever are in the situation to depend on it!
A CCTV digital video recorder (or “DVR” for short) is essentially a computer that saves security video images to a hard drive. Most security cameras in use today capture an analog picture. The DVR converts the analog signal to digital and then compresses it.
Many cameras can be connected to one DVR. DVRs generally come with 4, 8, 16, or 32 camera inputs. The DVR will allow you to view all of these images at once or one at a time, and all of the video is saved to the hard drive. Additional switches, quads, or multiplexers are not required.
A security camera can come in many different styles including dome, bullet, infrared and c-mount. The security camera that will work best for your application will depend on several factors such as whether you will use the security cameras inside or out, during the day, nighttime, or both.
Bullet style security cameras are the most popular. They can be used inside or out. These security cameras come in black and white or color and come with all of the required mounting hardware. The security camera casings are weather resistant and don’t require added external protection. Most security cameras have a fixed 4mm lens that allows you to see facial features out to about 35 feet and provides a 70 degree angle of view. This is the widest angle you can have without distorting the picture. Click here for more information about bullet security cameras.
Resolution levels for black and white security cameras are about 400 lines, any higher and the benefits are minimal. For color cameras, the higher the resolution the better.
Infrared security cameras are also very popular as they allow an image to be seen in little or no lighting conditions. Most infrared security cameras are bullet style and can be used inside or out. The cameras have infrared lighting installed around the outer edge of the lens which allows the security camera to see in no light for up to 25 feet – even further with a little bit of light (like street lighting or an outside light.) Click here for more information about infrared security cameras.
A relatively new type of security camera to the market is the day / night security camera. These types of security cameras have an extra sensitive imaging chip which allows it to capture a good picture in low light situations without using infrared leds. This is especially handy in outdoor applications because infrared security cameras do not do well in outdoor housings. Unless the infrared security camera is installed flush up to the glass of the housing, the infrared lights can reflect off of the glass of the housing which degrades the image.
The advantage to c-mount security cameras is that the lens can be changed. You’ll want a special camera lens if you need to see further than 35 ft. The color c-mount security camera allows you to change lenses on the camera giving you the ability to zoom into a particular area. Varifocal camera lenses allow you to adjust the focus from 5 to 50 mm. These lenses can be used inside only unless you put it in special housing for outdoor use. Click here for more details about C-Mount security cameras or Security Camera Lenses.
Dome security cameras basically provide a different look. Also, if you have any concerns about tampering, check out our Infrared Armor Dome Security Camera. It will withstand a 10 lb sledgehammer blow and can be used inside or out, daytime or nighttime. Click here for more facts about dome security cameras.
How far you need to see will determine what security camera lens you should use to best fit your application. A 4mm lens will give a 70 degree angle of view with 35 feet of facial detail. This works great for residential or small office security camera applications. If you need to see further you would go with a higher powered lens. Keep in mind that the further you want to see will narrow the field of view of your picture.
A rule of thumb is that a 8mm lens is like a 4mm lens zoomed in 2 times. Similarly, a 16mm lens is like the 4mm lens zoomed in 4 times. For example, a 16mm lens would give you about a 15 degree angle of view focused at 35 ft.
What If I Do Not Know Exactly How Far I Need To See?
Instead of going with a fixed focus lens you can go with a varifocal lens. With a simple adjustment you can manually zoom in or zoom out and focus the camera to the exact distance needed to get a clear picture. Varifocal lenses come in all different sizes: (3.5-8mm; 9-22mm; and 5-50mm) just to name a few. This is the best option for large commercial applications because you can adjust the focal distance to what works just right.
What is a PTZ camera?
A Pan Tilt Zoom camera (PTZ) allows you to pan (back and forth), tilt (up and down), and zoom (focus in and out) your camera remotely. The PTZ is controlled using a remote PTZ controller or you can control it through most DVRs (look for PTZ support). The disadvantages of a PTZ camera is that they are very expensive (usually around $1000 without the controller). And all the moving parts make it susceptible to wear and breakdown. There are some new digital versions of PTZ cameras just coming on the market that have no mechanical parts. These PTZs are very promising but are still a little too expensive to be practical for most uses. PTZ cameras require a data cable to be run to the camera in addition to the video and power cables. Unless you have a person who is watching the scene and adjusting the field of view of the camera based on what’s going on its not as useful. Most times you are better off buying more of the non-PTZ cameras to continuously cover the area rather than a PTZ.
What is the difference between no iris and auto iris?
The iris controls how much light is let into the camera lens. In the old days, cameras came with no iris control. If you needed to control the light levels you would have to purchase a special lens. Nowadays, most cameras come with automatic shutters which perform the same function as the iris – controlling how much light is let into the camera. Unless you have an application with extreme light levels (like at a beach) you probably won’t need a special lens with iris control.