Overview

What is Zoom?
Zoom is the feature of the lens of the camera that allows changing the focal length automatically using the built-in motor. The longer is the focal length, the farther the camera can zoom into, making the distant objects look much closer and therefore these objects become recognizable.

It is also possible to zoom-out, to get wider view of the scene for better overall situational awareness. For that, the zoom motor will shorten the focal length to the minimum.

What is Zoom Ratio?
The difference between minimum and maximum focal lengths of each zoom lens is called "zoom ratio". For example, when the minimum focal length is 10mm and maximum is 200mm, then the zoom ratio is 20x, which is the result of the 200/10.

Manual or Auto Zoom
The zoom lens can be operated manually using remote controls via VMS or camera interface, or automatically, based on pre-set points or event rules. For example, when the zoom camera sees the moving objects, it may automatically zoom in to capture the close-up view of that object.

Surveillance Zoom vs Installation Zoom
There are two types of zoom lenses - surveillance grade zoom lenses and the installation grade zoom lenses. The surveillance lense motors are quick, they work under wider temperature ranges and they are very durable for a very long time. The high-end quality models have surveillance grade zoom capability.

The budget-oriented camera models may have the installation purpose zoom motors - these motors are mostly used to adjust the viewing angle remotely during the initial setup of the camera. This is more convenient that manually adjusting vari-focal lenses on the ladder, for example.

Types of Zoom Cameras
ACTi offers a wide range of zoom cameras with both surveillance and installation grade zoom lenses, including PTZ, zoom box, zoom bullet, zoom dome and even multi-imager cameras with the zoom lenses.

What is Auto Focus?
Whenever the focal length is changed, the focus of the camera shifts. In case of the vari-focal lenses, the installer would have to adjust the focus manually using the lever on the lens. The Auto Focus cameras have a dedicated motor, that can adjust the focus without requiring any person to touch the camera at all. The camera evaluates the scene and adjusts the focus by itself, to make the current view to be in the clear focus. Alternatively, it is also possible for the monitoring person to override automatic focus by using the remote focus controls via VMS interface.

Zoom and Auto Focus Combined
Every camera that has a zoom capability, also has the auto focus capability. So whenever the camera zooms in or out automatically or by the remote control, the auto focus will be applied automatically.

Preset Zoom and Auto Focus
It is possible to define specific preset points for zooming in or out. While going to these pre-set points, the camera already knows what the correct auto focus position for each preset point it. Therefore, whenever the camera has to move to that specific preset point, both zoom and auto focus motors work simultaneously so that the the preset point view can be clearly exposed instantly.

Applications

The surveillance zoom applications include large perimeters, corridors and other scenes where zooming in can help recognize the target objects from far distances.

The application of the installation grade zoom lenses is the labor cost saving. Traditionally, when the viewing angle needs to be adjusted, the service team with the specific equipment has to be called. This service call might be costly. However, with the simple mouse click on the VMS screen, it is now possible to adjust the viewing angle and the focus without requiring any service calls.

Solutions

ACTi VMS products support all the zoom lens cameras, regardless of the form factor. For example, when you are using ACTi's NVR 3, you can use zoom-in and zoom-out controls to operate any of the zoom cameras in the current view. You can use buttons or mouse clicks on the video.

At the same time, it is also possible to use joystics or control panels, plugged to the VMS client computer.

The preset zoom positions can also be configured using VMS interface.