CCTV Camera View Distance at Night I How Far a CCTV Camera Can See at Night I How Far an IR CCTV Camera Can See at Night I How Far an Infrared CCTV Camera Can See at Night I How Far A Thermal Camera Can See at Night Maximum Distance a CCTV Camera Can See at Night I How Long a CCTV Camera Can See I CCTV Camera Night View Capacity I
This is very genuine question to ask to the supplier or installer before fixing the camera.
Now , we will answer this question in two steps , first a command answer for the people who do not want to go into technicality of the things and just want to go the summary and later on we will discuss in detail about the principal of science involved .
First , let us see how far a camera can see in day time ? In general term , a good camera can see as far as your eyes , whether the clarity of the view depends on many factors such as Pixel of Lens , FOV , Light condition and weather condition . Please visit our blog ……..how far a camera can see ……….for more details . The same happens at night ( for a CCTV Camera there is no difference if a clock is showing AM and PM if other measures are same ) , if camera is provided with light even in night, it will record and see to same distance as in day time i.e. till our eyes can see . But it is not the case in reality.
Now as most of the other factors will remain almost same at night as in day leaving one , which is optimum “LIGHT and obviously which is the most important aspect in photography or video surveillance industry .The distance to which an Infrared Night Vision Camera can see entirely depends on the Night Vision capability(quality and power of Infrared Illuminators Used ) of the cctv and on camera placement . There is no any fixed limit for the distance but , things like distance , ability to focus and what the camera is designed for will make a “soft limit “ on useful range . You can not see the vehicle number plate from the top of a 20 storey building , but you might get all the useful information needed .
A particularly high-end IR camera at night is almost as good as it is during the day; some of the detail will be lost at long distances but for the most part, limits will depend on where the camera are placed.
A mid-range IR camera at night will loose a lot of detail, but then also the footage is still good enough to get a rough identification of people . thease are the cameras which are a common in use these days . If we place the cameras at right place with IR sensor properly, we will be getting quite a good footage by these cameras.
A cheap night-vision camera is still better than a regular camera at night, but detail is going to be limited at range. We can use these cameras in lift , for very small place or on entrance door . These cameras will perform well at these places as darkness won’t affect much due to very short range .
In normal scenario a good 2mp ir bullet modern “cctv” camera can see ~100′ at night.
Read Our Blog …..11 Ways to Increase Night Vision Capability of your CCTV Camera .
We have given a general idea about the distance upto which an IR CCTV Camera can see . Most of the manufacturers gives IR distance for their product on the box and on website . Also you can calculate the IR distance for your products if you know the other details from the site of the many manufacturers who has given the calculator on their website .
Link-IR Distance Calculator for CCTV Cameras
Lets discuss the technical aspect
Being a marketing person in security system product sales , I have to face this question more often than not ( and If you ask me , I really don’t like this question ) . My answer to the above question would be : it depends , which again open opens flood gate of many questions and explanation thereon .
The answer to above question ( How Far It Sees at Day/Night ) needs some questions to be asked to the customers also i.e. What they want to see ?
Lets classify the word “Seeing “ into subset as we do in the camera industry and that is Detection , Recognition & Identification .
We are seeing a movement far away and not sure it is an animal , human or some other object is detection , which needs less resolution .
Now we can recognize it is a human , male or female and also have idea about build type , ethnicity etc , it is recognition and needs more resolution than detection .
To Identify the person who is he/she is exactly , needs much more resolution than the detection .
Resolution is commonly defined by the number of pixels that the camera offers. Standards are 320 x 240, 640 x 480, and 1280 x 1024. The number of pixels in the camera is only one factor in determining how far it can see. Another is the lens. The longer the focal length of the lens on the camera system, the longer the physical distance that a camera can detect, recognize, and identify a target.
Field of view
We classify the lenses in terms of their focal length, for example 25 millimeters (mm) and by the lens’ field of view (FOV) such as 9 degrees. Typically, the longer the focal length, the smaller the FOV.
Field of view of a CCTV Camera ( Lens) is what ( How Much ) we will be able to see through the CCTV camera.
The field of view (or FOV) is the total height and width of the view seen through the cctv security camera lens. It can also be referred to as the angle of view or the angular field of view.
The field of view ( or angular field of view ) is described in horizontal and vertical degrees . This is the degree of a circle . The full circle is of 360 degrees . In the below picture if you put a camera lens at the centre of the circle , and if the lens’s field of view is , you will be able to see it the area of the dark blue section , which is coming 43.6 degree .Hence the lens’s field of view of angle of view can be taken as 43.6 degree .
Here we are talking about the CCTV field of view of CCTV Cameras and when people ask this , actually they are looking for a linear field of view of the cctv lens.They are looking for the actual measurement in Mtr and Cms.
The Horizontal FOV (Field of View) is the width of the view. The Vertical FOV (Field of View) is the height of the view. The overall FOV is a combination of the horizontal FOV and the vertical FOV.
How to Calculate the FOV
For the people who are good at Mathematics , they know it . But to keep it simple here is the way .
Before calculating the FOV , we must have some details ( raw data ) to proceed . We need the dimension ( size ) of CCD imaging device in the Camera . Below given is the chart of different CCD sizes and their corresponding actual dimension .
Now you need at any two of these three data (measurement ) .
- The Focal length of the lens – Such as 9mm
- Distance to the object/scene
- Width of the object/scene
Mostly we will be knowing the distance of the object or scene and the approx width of it . This way we can calculate the focal length of the lens which is needed for your CCTV Camera .
Please download the CCTV FOV calculator and use it to make the calculation simple. Click to Download .
As the CCD size of 1/3 inches are the most common sizes used in CCTV Cameras , we have made calculator based on that size for CCD. Now you can put other details in the calculator .
As an example if your distance to the object in the scene is 80 feet. The width of the view that is desired is 10 feet. Enter those numbers into the calculator in the lower section. The resulting focal length of the lens should be 38.4mm. To see how that translates into degrees of view you can enter 38.4 into the upper Focal Length box and you will see the corresponding degree of view in the right circle. It should show 7.15 horizontal degrees of view.
Few installer use the circular field of view calculator instrument to check what size of lens they need at particular location or particular purpose . But in our view it is not necessary . We can check that by doing a simple calculation .
Measure the distance to the object and divide it by the desired width for the view and then multiply that by the image size. Referring to the CCD image size chart above you will see that the size for a 1/3rd inch sensor (which is the most common) is 4.8mm for the horizontal measurement. So , lets for example take the distance 80 feet divided by the width of 10 feet and multiply by 4.8.
Lets do the calculation like this. 80/10*4.8 = 38.4
Here you GOT IT This a a fast and easy way to calculate the focal length needed for your CCTV Camera.
Now , as we have learned about the FOV of the camera in general now the different lenses are designed for certain sensor and detector sizes . In visible cameras , this is called lens format . If a lens is designed for ¼ inches sensors , it will not work with imaging sensors which are of ½ inche format . If the combination is not perfectly matched , it will not give even image and the image will be with dark spot in the periphery and light at the centre . When it is used with right combination, the lense will project full image across whole sensor .
In infrared video surveillance systems, lenses are specifically designed for focal plane arrays (detectors). IR detectors are not designed like visible lens formats. A pixel has its dimension which is mostly square and its dimension is measured in micrometers( microns or µm ) . So if a detector that has 17 micron square pixels, and – 640 pixels across and 480 pixels vertically, the detector has a total size of 10.88 millimeters x 8.16 millimeters, and has a diagonal of 13.6 millimeters. When we compare it to visible lens formats, 13.6 millimeters is approximately one-half inch. When we think about it in visible terms, this would be a ½ inch format lens. In the infrared video surveillance industry, most infrared lens catalogs will specify the lens size against the number and size of pixels.For instance, a lens data sheet will state that it is compatible with infrared detectors which are of a certain resolution (640 x 480) and of a certain pixel size (17 µm).
To make a statement, the FOV in the infrared camera is determined by the focal length of the lens and the size of the detector. If we take a CCTV Camera of 50 mm lens (focal length) and a detector with 640 x 480 pixels that are 17 µm, the field of view can be calculated as 12.41 degrees horizontal.
Now see it by a simple example of using your display (computer or television monitor). If you take it from left edge of the display to the right edge of the display, there are 12.41 degrees. One is spreading 640 individual imaging elements (pixels) across 12.41 degrees field of view. Now , considering how big the object which has to be seen is and how distant it is , we can formulate detection , recognition and identification decisions.
This took us back to the our main question , “How Far A CCTV Camera Can See at Night ?” And answer is, given the parameters above (50 mm lens, 640 x 480, 17 µm detector) a one meter target can be detected (fills two pixels) at 1,471 meters away. It can recognize an object (fills eight pixels) at 368 meters away. It can identify a target (fills 13 pixels) at 226 meters away. If we take object as larger targets, it increase the distance and Stronger criteria (more pixels assigned to detection, recognition, and identification) would reduce the distance.
( IFOV) Instantaneous field of view
Another method, used by many in the infrared industry, is to calculate the instantaneous field of view (IFOV). IFOV measures what each pixel can see versus what the entire array of pixels can see. It is generally measured in terms of micro radians (µrad). A radian is taken as te the angle which is made as a result of wrapping the length of the radius of a circle, along the edge of the circle. By using the same parameters as earlier (50 mm lens, 640 x 480, 17 µm detector) each pixel in the system will have an IFOV of 0.33 µrad.After knowing this, one can calculate strong data for a given distance. At a distance of 1000 meters, each pixel will account for 34 centimeters horizontally. All the horizontal pixels together will result in an image that is 218 meters wide.
Determining these measurements requires trigonometry Calculating these measurements need a good hand a Trigonometry and unfortunately I am not the guy for it and I am not sure about you . Fortunately for people like me, to calculate the fields of view or IFOV to understand how far an imaging system can see,there are some excellent FOV calculators which are available on the internet . You have to look for one which provides both the standard FOV and the IFOV. You have to fill the specs of the camera you want to calculate FOV & IFOV in the calculator .The specifications and lens data are available on the camera box and lens . After that, just check or know how big your target is and you will be able to answer the question, “How far can you see at night using IR Night Vision CCTV Cameras ?”