Types of Zoom: Digital Versus Optical Security Cameras

If you are in the process of shopping for a new security camera system, you've probably run across the terms digital and optical zoom when you're looking at cameras' specifications. You might be wondering, "What's the difference between digital zoom and optical zoom?" But before we dive too deeply into the different types of zoom, you need to understand how the cameras can zoom in the first place. We use two different lens types in our cameras that are standard across the industry: fixed lens and varifocal lens. You're probably familiar with fixed lens cameras. They're the traditional point-and-shoot style. However, cameras with varifocal lenses can change the focal length of the lens mechanically. This mechanical changing of the lens gives cameras with varifocal lenses the ability to zoom.

With that understanding let's dive into the different types of zoom and how each applies to specific applications. Security cameras have two types of zoom--digital and optical. When shopping for a new CCTV security camera, keep in mind that it may have one or both. If you're in the research phase and wondering which type of zoom is best, you should think about your priorities. What are your problem areas? What do you need your security camera(s) to see? The answers to these questions will help you understand which type of zoom is right for you.

Digital Zoom

When you use digital zoom, the camera is enlarging the picture area at the center of the frame and crops the outer edges of the image. Every camera we carry has digital zoom, even the ones with optical zoom. Digital zoom makes the pixels larger, so starting with more pixels makes the image less blurry. 4MP cameras are two times the quality of 1080P, so you can zoom in two times more and have it look and feel like HD 1080P. 4K cameras are four times the quality of 1080P, so you can zoom in four times more and have it look and feel like HD 1080P.

Advantages of Digital Zoom

Digital zoom's main benefit is that you can zoom in after your camera has recorded a video. There's no limit to how much you can zoom in digitally, but our NVRs stop after a little while because it isn't super useful.

Disadvantages of Digital Zoom

The main disadvantage of digital zoom is that you lose picture quality. For example, as you zoom in further, the picture will appear more pixelated.

Optical Zoom

You have used optical zoom before. When you twist a pair of binoculars, you are physically moving the lens further or closer to the optical sensor (in that case, your eye). The closer the lens is, the wider your angle of view and the more zoomed out things look. The farther the lens is from your eye (the optical sensor), the more narrow your field of view and the more zoomed-in things appear. This is why cameras are described as having a "4mm lens." The lens is 4mm away from the image sensor.

Advantages of Optical Zoom

Optical zoom's main benefit is that the picture will remain clear as you zoom in optically. A high-optical zoom security camera gives you effective surveillance from long distance. You can see smaller details from farther away (faces, license plates).

Disadvantages of Optical Zoom

Zooming with a high-optical zoom security camera magnifies and narrows your field of view. Additionally, there's a per-camera mechanical limit on how much you can zoom in.

This image was taken at a 4mm setting. Pay attention to the power box that is down the hill from the red car. We're going to zoom in on it using digital and optical zoom.

This image was taken using a 20X digital zoom. It looks blurrier because you are limited in how many pixels you have. We've captured the whole picture, but zoomed in afterward.

This image was taken using a 20X optical zoom. It looks clearer because the image is magnified to fill the whole sensor. This allows you to capture a crisper image.

Types of Optical Zoom

When you're comparing specifications on different cameras you are likely to see a few different terms that all refer to different types of optical zoom. It's important to understand these terms and what they really mean:

Varifocal Lenses

You operate a varifocal security camera by turning a knob. This means that you can only adjust the level of zoom in person and once you've taken the camera out of its waterproof enclosure: picture.

Motorized Varifocal Lenses

You operate a motorized, varifocal lens camera by clicking on a button on your NVR or surveillance app. You can zoom in while your camera is recording a video, but the camera itself does not move around. You will be limited to where you have pointed the camera. You can adjust cameras with motorized optical zoom via the on-screen controls on your NVR or app.

PTZ Lenses (Pan, Tilt, Zoom)

PTZ cameras are fully motorized. You can change where the camera is pointed and the level of zoom. Most PTZ cameras can pan around 360 degrees, tit up to 90 degrees, and zoom in more than any other type of camera.

How Much Zoom Do I Need?

If you're still wondering which type of zoom is best then it's important to remember that it really depends on your unique situation. A good rule of thumb is that if you want to ID someone at 100 feet, you need at least 4x zoom. If you're going to ID someone at 200 feet, you need 20x, and if you need to recognize someone at 250 feet, you need 30x zoom.

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