Varifocal and Fixed Lens for Your Home Security Camera System

13/10/2015 0 Comment(s) Surveillance Equipment,

Choosing the appropriate home security camera system is a major decision for homeowners who want to optimize the protection of home and property. Security cameras are deployed outdoors to keep intruders away and to have ample evidence when unknown persons try to gain unauthorized entry into the house. Indoors, security cameras serve as a baby monitor and as a means to obtain records of the activities of children who remain at home with a sitter. In other words, you can use the cameras to monitor situations in the house while you are away.


Cameras come in all forms and types, with a myriad of features that can confuse an average person who has a very basic knowledge of security cameras and this work. A basic understanding of what type of lens the camera is equipped with can be very useful when it is your first time to shop for a security camera.


Varifocal and Fixed Security Camera Lenses

 

Camera Lens

When choosing a home security camera system, it is important to make a careful study of your home to identify the locations where you will install these devices. Most definitely, you will want clear pictures of certain areas in and around the house, so the feature of the camera that counts most is the lens with which it is equipped. The camera lens determines the size of the area that the camera can cover and how much detail will be seen from each image taken at certain distances from the camera.


One of the basic parameters when using a camera is the focal length that determines image magnification and the angle of view. Focal lengths are measured in millimeters (mm), with cameras having shorter focal lengths, giving a wide angle of view, which is measured in  degrees. The angle of view is an important consideration for video surveillance cameras because it represents the span of the area that the device can monitor. As the focal length is increased, the angle of view proportionately decreases and the image details become more defined.


The lenses are classified according to the angle of view. A normal lens gives a 50o angle of view of the diagonal, while a wide-angle lens has an angle of view that is wider than 60o. A fixed lens camera has a non-adjustable setting, meaning its focal length remains at a certain value, usually giving an overview that is similar to that seen by the human eye. A varifocal lens camera, on the other hand, has multiple focal lengths that allow the user to change the focal length manually, so you can zoom and focus on specific areas.

 

Fixed vs Varifocal Security Camera

Your choice of camera directly affects the cost of the home security system. Because the fixed-lens security camera is much cheaper, many homeowners choose it over the more expensive varifocal camera. However, it is best to plan for the positioning of each security camera before purchasing the devices because there are certain advantages to using a varifocal camera instead of the fixed-lens camera. In most cases, it is advisable to use a combination of both camera types.


Fixed-lens security cameras are the cheapest and simplest on the market. The spot where it is to be installed should allow you to focus the camera on the spot of interest, meaning the area for monitoring should be well within the camera’s angle of view. The choices for fixed-lens cameras can range from a lens size that will give a 30o angle of view to a lens size that will give a wider angle, for example 60o. The camera that has a 30o view will provide more image details, while one that has a 60o angle of view may lose some of the smaller details but will cover a larger span of the area.


Fixed-lens cameras with narrow angle of view are best installed in doorways, hallways, or entry and exit points. With the narrow-angle view, you will get sufficient facial details to identify the persons who move in and out of the area. Once the fixed camera is installed, the angle of view cannot be adjusted or re-focused unless you take it down and re-position it in another spot to get a better view of the area. Re-installation of the camera means additional expense, so before fixing it in place, you have to power up the camera and view the space on which it is focused.


When you purchase a fixed-angle camera, you are stuck with the angle of view it provides. For example, if you bought a wide-angle fixed-lens camera for monitoring a small room and then decide that you want a tighter image, you have to replace it with another unit that gives a narrower angle of view. Conversely, when you get one with a longer focal length and then decide that what you need is a camera that will give a wider angle of view, you have to ditch it for a more appropriate camera with a shorter focal length.


The Varifocal camera is more expensive, but it provides consumers with more options and has fewer constraints in use and installation compared to the fixed-lens camera. The varifocal allows you to adjust the focal length, which means you can adjust the angle of view of the camera, from the widest angle that corresponds to the shortest focal length, to the narrower angles that allow you to focus on certain spots.


When buying a varifocal camera, you should look for a model that has a wider focal length range because it will give you more freedom to adjust the angle of view. You can set the focal length manually when you install the camera to get the desired coverage of the area that you want to monitor. For example, some models of varifocal camera like the 1/3" Sony 720P High Definition CMOS sensor camera with 2.8 to 12mm varifocal lens. The varifocal camera is appropriate for business and residential security systems where large areas require surveillance. The varifocal lens can be adjusted manually for wide angle and close-up images.

 


Review the images from the camera before fixing it in position to ensure that it is of the correct distance from the target area for monitoring. Once you have positioned the fixed lens or zoomed the varifocal camera, that is the view that you will see from that point on when viewing from the monitor or watching recorded video.

 

Conclusion

Varifocal and fixed lens cameras are appropriate components for a home security camera system, the latter for its affordable price and the varifocal for flexibility of use.

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