**GarryB** 13/03/15, 01:37 pm

Actually some cameras have very long range, but the problem with very long range is high magnification which limits field of view so you end up having to scan a large area with a high mag lens it ends up like looking though a straw to find things.

Very high altitude UAVs need high power cameras just to see the ground clearly... a drone flying at 15km altitude needs a camera that can see enormous distances... a target 20km away from the drone horizontally... well Pythagoras theorem says you can calculate the longest edge of a right angle triangle by squaring the other two sides and adding them together and square rooting the result... so 15 x 15 plus 20 x 20 equals 225 + 400 which equals 625 so the square root is 25, so to see 20km away from 15km altitude the camera has to be able to see at least 25km.

A while back I was looking through Various Russian optics websites I found one website that specialised in very high resolution very high magnification optics.

The example on their front page showed a city landscape photo that zoomed in multiple times to the point where buildings that were 20km away could be zoomed in so the image showed individual rooms on a building...

It really annoys me that I don't seem to be able to find it again....