How does one calculate the actual field of view, i.e the width of the image that you will see at 1000 yards from the Field of View angle stated by the manufacturer?
And how does one reconvert it. For example, what would be Field of View (in degrees) of a of a pair of binoculars, if the manufacturer's date states ,"Field of View at 1000 yards is 300 feet".
I will apprciate any help. Thanks.
[QUOTE=turumti]How does one calculate the actual field of view, i.e the width of the image that you will see at 1000 yards from the Field of View angle stated by the manufacturer?
And how does one reconvert it. For example, what would be Field of View (in degrees) of a of a pair of binoculars, if the manufacturer's date states ,"Field of View at 1000 yards is 300 feet".
I will apprciate any help. Thanks.[/QUOTE]
The equation Angle=2(atan(.5FOV/Dist)) will get your there. Because of edge distortions, etc. usually atan(FOV/dist) would be a close enough approximation. For example atan(150/3000)=2.8624d degs. times 2=5.7248 degs.
atan(300/3000)=5.7106 degs,
Going the other way FOV=2(tan(1/2 angle)*dist)) or approx. FOV=tan(ang)dist.
Ron