Purchasing a security camera system can be a potentially tricky endeavor: intricate parts interact in these systems, making them extremely difficult to comprehend.

 

How to Choose the Best Lens for Your Security Camera

How to Choose the Best Lens for Your Security Camera

Purchasing a security camera system can be a potentially tricky endeavor: intricate parts interact in these systems, making them extremely difficult to comprehend. The camera, accessories, DVR and monitor all affect the quality of the final recorded image. One accessory that can easily trip up a prospective security system owner is the surveillance camera lens. There are many factors that affect the functionality of a camera lens as well as its compatibility with any given security camera. An ill-suited lens can restrict image quality, so before investing in a state-of-the-art security network, one should get acquainted with the qualities that define a camera lens.

Focal length and field of vision

The first specification to consider when choosing a security camera lens is its focal length. The focal length of a lens determines both the range and distance of its field of vision. The basic rule to remember is that a smaller focal length will lead to a wider viewable range. Conversely, a larger focal length will have a more narrow field of vision, but it will also have a farther range. A 2.8mm lens would be ideal for capturing images in a wide field within 20 feet or so, but a 12mm lens could grab a clearer image of an object farther away. A lens with a focal length around 8mm would split the difference between the two extremes.

Image format

In order to maximize image quality, the image format of a lens should match that of its paired camera. All security cameras have an image sensor installed inside of them. These tiny mechanisms are vital to the process of recording objects. Essentially, they take captured light, convert it into electrons then assemble the result into a viewable image. Image sensors are sorted by their type, listed as a fraction of an inch. The larger the fraction, the larger the field of view available. However, all lenses have a maximum image sensor size that they will be compatible with. If a camera with that ½” image sensor is paired with a ⅓” lens, such as this Arm model, the field of vision would be the same as a camera with a ⅓” sensor. When pairing a lens with a camera, it is very important that the lens' image sensor compatibility be the same size or bigger than the camera's.

Monofocal, varifocal and zoom lenses

Lens types can generally be sorted into three different categories, monofocal, varifocal and zoom. The most basic and least expensive of the group is the monofocal lens. These lenses have a fixed focal length, allowing them to only focus on objects at a specific distance. Varifocal lenses, like this one from Fujinon, have a focal length range that the user can manually adjust to alter the range of vision. The most expensive variety is the zoom lens. They are similar to varifocal lenses in that they have a focal length range; however, instead of needing to be manually adjusted, the lenses do so electronically.

Aperture

A lens' aperture is the hole that light passes through to enter the camera. The size of the aperture is measured in f-stops, where a lower number indicates a wider aperture. A larger aperture will allow for more light to pass into the camera. The aperture also affects the depth of field. A higher f-stop number and narrower aperture captures more objects in focus, whereas objects viewed with a wider aperture may appear blurry.

Iris

The flexibility a surveillance camera lens has processing light is dictated by the type of iris it has. The iris influences how much light passes through the lens' aperture. The two basic varieties of irises are manual and auto. A manual iris allows for a fixed amount of light to pass through the aperture, making it ideal for an indoor conditions with little to no lighting variance. In a situation where light levels are going to fluctuate, like surveying an outdoor environment, an auto iris lens, such as this Pelco model, is required. As its name implies, this variety of lens senses and automatically adjusts to accommodate different levels of brightness.

Like security cameras, lenses come in many different varieties. When choosing a lens, it's important to realize what its intended function is and what limitations it may not be able to overcome. Different surveillance conditions call for a different camera and lens. An informed shopper should know what lens is best suited for his or her needs before making a purchase.

A1securitycameras.com is available and ready to help you with any questions you have concerning lenses or other security equipment.

Dec 29th 2021 richard

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