Subscriber Discussion

4K Digital Zoom To 800ft

Eric Moreau

•Nov 02, 2015

If you have a 4K camera with a 5mm lens; Is there a way to calculate the digital zoom of the camera? I know I need to get the 4K camera to zoom into an area of 52' wide and 800' away.

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John Honovich

•Nov 02, 2015

IPVM

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.

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Undisclosed #1

•Nov 02, 2015

IPVMU Certified

In reply to John Honovich

Maybe even a bit worse, since 4K cameras typically have larger sensors.

For instance this Dahua is 3.7 Ppf with a sensor of 1/2.3".

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Mike Dotson

•Nov 02, 2015

Formerly of Seneca • IPVMU Certified

Eric,

Be sure to decide if you really want Digital Zoom or Optical. They are very different.

The IPVM article that discusses this is HERE .

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Undisclosed Manufacturer #2

•Nov 03, 2015

Hello Eric,
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,

Henk Heijmink

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