How To Choose The Right Lens For Your Surveillance Application
Choosing the correct lens for your surveillance application can be one of the hardest and sometimes most confusing decisions to make when selecting the correct camera for your purpose. When you're looking to capture a wide area, such as a full parking lot, you will not be able to capture extreme details at far away distances. Even though some cameras have higher resolution than others, sometimes it's still hard to see exactly what you need to. However, please note that the better the resolution, the more likely you are to capture the extra detail that will help you identify more detailed characteristics in a scene. The better the camera, DVRresolution, frames per second, and monitor, the better the footage will be.
Some people have asked us, "What is a Varifocal Lens?" A varifocal lens has the ability to zoom in and focus on a specific area manually. This works the same as a DSLR camera where you must focus and zoom using your hands other than software to remotely controll the camera. However, the more you zoom into an area, the more you have to sacrifice horizontal coverage. The best solution would be to have multiple cameras for your application which will assist in capturing up-close detailed shots as well as one with a wider shot that will cover more area.
A Pan Tilt Zoom Camera (PTZ Camera) is another great solution. As the name suggests, these cameras will allow you to not only zoom into an area but remotely control it to pan and tilt as well. This will give you the advantage of controlling the camera in order to point it exactly where you need it. Some PTZ Cameras even come with an auto tracking feature which will automatically follow an object or person dependant on how sensitive you set the cameras sensors.
Image Sensor Size
One other factor that will effect the type of view you get will be the size of the image sensor on the camera itself. Always remember the larger the image sensor, the wider the view when using the same lens. We don't carry many cameras which have a 1/4" image sensor. It's generally better to use a larger sensor since it will give you a wider viewing angle and will capture more light which will help the camera function better in lower light situations. Many companies will advertise their cameras as being 1/3" when in reality they are 1/4". Please also note that there are higher quality 1/4" image sensors as well as a ton of poor quality 1/3". The general rule is that the larger sensors will provide a sharper image, lower light capabilities, and better color saturation when compared to the same exact camera which has a smaller image sensor. Also, the size of the camera itself does not mean that it's going to have a better or larger sensor.
We have created this chart below to help you better understand what kind of angles and distances you will capture:
|1/3" CCTV Lens Chart|
|Lens Focal Length||Distance Between Video Camera and Video Subject Area|
|Camera's Viewing Angle||5' (1.5m)||10' (3.0m)||15' (4.6m)||25' (7.6m)||50' (15.2m)||100' (30.5m)|
|mm||Horiz.°||Vert.°||Diag.°||H area||V area||H area||V area||H area||V area||H area||V area||H area||V area||H area||V area|
|2.80||109°||82°||136°||14.0' (4.3m)||10.5' (3.2m)||28.0' (8.5m)||21.0' (6.4m)||42.0' (12.8m)||31.5' (9.6m)||70' (21.3m)||52.5' (16m)||140' (42.7m)||105' (32m)||280' (85.4m)||210' (64m)|
|2.97||104°||78°||130°||12.3' (3.8m)||9.6' (2.9m)||24.6' (7.5m)||19.2' (5.9m)||36.9' (11.3m)||28.8' (8.8m)||61.5' (18.8m)||48' (14.6m)||123' (37.5m)||96' (29.3m)||246' (75m)||192' (58.5m)|
|3.60||74°||56°||92°||7.5' (2.3m)||5.7' (1.7m)||15.0' (4.6m)||11.4' (3.5m)||22.5' (6.9m)||17.1' (5.2m)||37.5' (11.4m)||28.5' (8.7m)||75' (22.9m)||57' (17.4m)||150' (45.7m)||114' (34.8m)|
|3.70||72°||54°||90°||7.3' (2.2m)||5.5' (1.7m)||14.6' (4.5m)||11.0' (3.4m)||21.9' (6.7m)||16.5' (5.0m)||36.5' (11.1m)||27.5' (8.4m)||73' (22.3m)||55' (16.8m)||146' (44.5m)||110' (33.5m)|
|4.0||67°||50°||83°||6.6' (2m)||5.0' (1.5m)||13.2' (4m)||10.0' (3m)||19.8' (6m)||15.0' (4.6m)||33' (10.1m)||25' (7.6m)||66' (20.1m)||50' (15.2m)||132' (40.2m)||100' (30.5m)|
|4.30||63°||47°||78°||6.1' (1.9m)||4.6' (1.4m)||12.2' (3.7m)||9.2' (2.8m)||18.3' (5.6m)||13.8'(4.2m)||30.5' (9.3m)||23' (7m)||61' (18.6m)||46' (14m)||122' (37.2m)||92' (28m)|
|5.0||50°||38°||64°||4.7' (1.4m)||3.5' (1.1m)||9.4' (2.9m)||7.0' 2.1m)||14.1' (4.3m)||10.5' (3.2m)||23.5' (7.2m)||17.5' (5.3m)||47' (14.3m)||35' (10.7m)||94' (28.7m)||70' (21.3m)|
|6.0||42°||32°||53°||3.8' (1.2m)||2.9' (0.9m)||7.6' (2.3m)||5.8' (1.8m)||11.4' (3.5m)||8.7'
|19' (5.8m)||14.5 (4.4m)||38' (11.6m)||29' (8.8m)||76' (23.2m)||58' (17.7m)|
|8.0||32°||24°||40°||2.9' (0.9m)||2.2' (0.7m)||5.8' (1.8m)||4.4' (1.3m)||8.7' (2.7m)||6.6' (2m)||14.5' (4.4m)||11' (3.4m)||29' (8.8m)||22' (6.7m)||58' (17.7)||44' (13.4m)|
|12.0||22°||16°||28°||1.9' (0.6m)||1.5' (0.5m)||3.8' (1.2m)||2.8' (0.9m)||5.7' (1.7m)||4.5' (1.4m)||9.5' (2.9m)||7.5' (2.3m)||19' (5.8m)||15' (4.6m)||38' (11.6m)||28' (8.5m)|
|16.0||16°||12°||21°||1.4' (0.4m)||1.1' (0.3m)||2.8' (0.9m)||2.2' (0.7m)||4.2' (1.3m)||3.3' (1m)||7' (2.1m)||5.5' (1.7m)||14' (4.3m)||11' (3.4m)||28' (8.5m)||22' (6.7m)|
|25.0||11°||8.4°||14°||1.0' (0.3m)||0.7' (0.2m)||2.0' (0.6m)||1.4' (0.4m)||3.0' (0.9m)||2.1' (0.6m)||5' (1.5m)||3.5' (1.1m)||10' (3m)||7' (2.1m)||20' (6.1m)||14' (4.3m)|
|50.0||5.5°||4.2°||7°||0.4' (0.1m)||0.3' (0.1m)||0.8' (0.2m)||0.6' (0.2m)||1.2' (0.4m)||0.9' (0.3m)||2' (0.6m)||1.5' (0.5m)||4.0' (1.2m)||3' (0.9m)||8' (2.4m)||6' (1.8m)|
*Most 1/4" CCD cameras produce a significantly narrower field of view with the same focal length lens. This chart displays angles based on 1/3" image sensors.
**Due to the physical nature of lens optics, these numbers listed should be considered accurate within ±3° and therefore a few feet/meters as well. The are approximate guidelines to help select the appropriate lens for your application. Each camera will have its own unique field of view depending on the lens. Also, the C- & CS-mount lense will typically have a slightly narrow field of view compared to our board lenses.