A HD-CVI varifocal camera with a motorized lens is able to remotely be controlled by zooming in or out. Apart from controlling the zoom directly via the DVR, you are also able to zoom by using a web browser such as Internet Explorer or Mozilla Firefox.
To activate the variable zoom feature on HD-CVI your camera, you need to make sure the camera is connected and properly configured to your DVR. This guide shows how to activate a HD-CVI varifocal zoom feature via web interface.
The instructions are applicable for any Dahua HD-CVI cameras and their OEM rebrands such as Activecam, Advidia, Amcrest, Ameta, Ascendent, Backstreet Surveillance, BV Security, CCTV Security Pros, CCTV Star, CP Plus (Orange Line), Dax Networks, eLine, ENS (formerly Eastern CCTV and SavvyTech), Expose, Lorex, GSS, Honeywell, IC Realtime, Ikegami, Impath Networks, Inaxsys, IndigoVision, Infinity CCTV, Innekt, Intelbras, KBVision, Lumixen, Maxron, Montavue, Oco, Optiview, Rhodium, RVI, Saxco, Security Camera King (Elite), Space Technology, Speco, ToughDog, Tyco Holis, Tyco Illustra Essentials, Unisight, VIP Vision, Watchnet, Winic, Zuum.
How to zoom a motorized HD-CVI camera via the web interface
First, connect the camera properly to your DVR. Connect the BNC input for the camera to the green wire and then connect the power adapter for the camera to the red connector (the power pigtail).
After that power up the camera. Also make sure the input BNC connector is securely fastened to the channel input in the back of the box.
After your camera is successfully connected to your Dahua DVR, you need to adjust a few settings on the camera. You can either do this directly with the camera or through the DVR’s web interface on a computer.
Basically you need to make sure the camera is on CVI mode. Many of these cameras support various signals such as CVBS, TVI, AHD, CVI, in our case you need to make sure the video mode is on HD-CVI.
One way to set the camera on HD-CVI is to use the toggle on the camera’s pigtail. Hold in on the center of the joystick located on the wiring of your camera for 5 seconds, then while holding in, move the joystick to the up position. The camera will then switch to CVI mode.
Once your camera is in CVI mode, we will need to change some PTZ protocols for the camera. In the web interface, click on Setup (gear icon) and then go to System > PTZ. In the PTZ menu, if the Control Mode defaulted to “Serial”, then on the protocol field select “EPTZ” and after that click Save to have the settings applied.
Additionally, if your camera’s Control Mode is defaulted to HD-CVI, please make sure the Protocol is set to HD-CVI as well and then Save your settings. So to conclude, if the control mode is Serial, choose EPTZ protocol. If control mode is HD-CVI, choose HD-CVI protocol.
Once the protocol is saved in the web interface, go to Preview and then test the Zoom feature located on the right side of the screen right above PTZ Setup/PTZ menu. The varifocal zoom feature will then be enabled for your camera. 
From the controls here, you can zoom in and out your HD-CVI motorized varifocal camera. Same thing can be done via the phone app (or tablet). These instructions are the same across all Dahua products (branded or OEM).
