You are going to get ~5ppf with a 4K camera, 5mm focal length at a distance of 800 feet away.
See this calculation for it on a map. It will probably be something like a 16x digital zoom and the quality will be pretty terrible. IF you need to see something that far away, you will need to use a longer lens.
let us know if we can help.
Seneca | IPVMU Certified | 11/02/15 07:12pm
Be sure to decide if you really want Digital Zoom or Optical. They are very different.
The IPVM article that discusses this is HERE .
An area of 52' wide at a distance on 800' requires a horizontal field of view of just 3.72°
It's impossible to say exactly what angle of view your 5mm lens will produce without knowing more details about the lens and the imager, but I suspect a 5mm lens will produce a wide angle, of say 75° (this is an estimation)
On a distance of 800', the lens will cover a horizontal area of ~1200'
With your 4000 x 3000 pixel 4K camera, you have 4000 pixels horizontally.
In a scene of 1200' wide, that is 3.3 pixel/foot.
For your scene, with digital zooming you have about 172 pixels available for your schene on 52'
With an aspect ratio of 4:3, your image will be a 129 x 172 pixels one.
Needless to say that this will be a very disappointing result.
You have a wider angle lens, but you really need a tele-lens.
Hope this helps,