8 Channel HD-SDI (3TB HDD) DVR 1080P CCTV Security Camera System with 8 x 2.1MP 1080P 2.8-12mm Varifocal Zoom Outdoor/Indoor Cameras (HDSDI - True HD 1080P, 100% more detailed than 1080P HDCVI or HDTVI)

What lens do I need covering an angle of?
Please view the table below:
Focal Length: Angle of View
2.8mm: 97.4 degrees
3.6mm: 85 degrees
4mm: 71.6 degrees
6mm: 44.4 degrees
8mm: 34.5 degrees
12mm: 22 degrees

Overview
HD-SDI 1920×1080P High Definition 8 Channel DVR with 8 x HD-SDI 1/3" 2.1 Megapixel 1080P Outdoor or Indoor Camera, 1920×1080 Pixel, 2.8~12mm Manual Varifocal Lens. Support E-SATA. iPhone, Android Viewing. HDMI & VGA. Preview, recording, and network live, backup, playback

DVR Feature
8CH Video-input, 2CH Video-output (VGA?HDMI)
8CH Audio input, 1CH Audio output (RCA)
1920x1080P Record resolution
8ch sensor input, 1 channel alarm out
Support VGA & HDMI, 1920*1080P Output
2 SATA HDDs, up to 8TB
Supports Remote View with each of those systems below: WindowsTM XP, Vista, 7 , 8, iPad , iPhone, Android

Camera Feature
GW788HDSDI: 1080P HD-SDI 1/3" 2.1 Megapixel CMOS Camera, Progressive Scan, 2.8~12mm Manual Varifocal Lens, Water proof and Vandal proof
*2.1 Megapixel CMOS image sensor
*Built in 2.8~12mm Manual Zoom Varifocal Lens which allow you to adjust the angle of View
*True HD 1080P (1920×1080) Video Output Mode
*Built-in 72Pcs IR LED, view up to 200 IR Distance

Package Includes
1 x GW1208HDSDI: 8 Channel DVR with Pre-installed 3TB Hard Drive
8 x GW788HDSDI: 1080P Manual Varifocal Zoom Camera
2 x GW100HDS : 100ft RG59 Combo Cable
4 x GW60HDS : 60ft RG59 Combo Cable
2 x GW25HDS : 25ft RG59 Combo Cable
1 x GW12V5A: Power Supply for Cameras
1 x GW128CA: 1 to 8 Power Splitter Cables
1 Year Warranty and Free Tech Support