Hello everyone, I still have 2 cameras to buy to finish my kit dahua and I'm not sure if I should take 2.8 or 3.6 the camera should be 20 feet from the subject and cover 20 feet wide so I'm waiting for your advice
Hi
@superpatpat
Many of us feel the Dahua DORI measurements are overly generous ( making the DORI distances too long ), do check out the DORI section of the
cliff notes.
In general I only like 2.8mm lens when the suspect will be close to the camera, and want 3.6mm or stronger for further away
A popular starlight model a few years back were based on a 2MP sensor, which for 100ppf ID distance from the DORI calculations came to:
Dahua IPC-HDW4231EM-AS starlight fixed lens 1080p 1920x1080 ( 2MP )
- w/2.8mm lens FOV H 110 degrees: 10 feet { area covered 95.94 sq feet covered }
- w/3.6mm lens FOV H 87 degrees: 12.65 feet { 121.43 sq feet covered }
- w/6mm lens FOV H 51 degrees: 21.58 feet { 207.16 sq feet covered }
A 8MP "4K" sensor will give you 2x the ID distance
or
w/2.8mm FOV H 110 :
20 feet
w/3.6mm FOV H 87:
25.3 feet
( this is assuming effective pixels, low light image capture will reduce the effectiveness, as will compression, fog, rain, glare, bright light, shade / bright in the same frame
.. )