# The mysterious Lens > FOV factor????

HI,

I’m currently working on an export script for Sportscar GT tracks and want to export blender camera data.

Jan Walters excellent series of articles on the Blender/python source record that the camera.lens value can be converted to a Field Of View value (radians or degrees - not sure) by:

FOV = 360 * arctan(FACTOR*16/Camera.Lens/PI)

The FACTOR is supposed to be dependant on the X and Y resolution values chosen.

Can anyone please tell me how this FACTOR value is derived and/or what a ‘standard’ value for it would be?

Is possible - does anyone know where it is defined in the 2.25 source - I’ve been hunting in vain!!!.

Cheers Stephen.

Ha Ha!!

I had a play around with measuring the (top down view) angle of the camera with a protracter ( :o ) and relating it to the Lens value. The conclusion I come to is that the formula is:

## FOV = (360/PI)ATAN((X16)/Camera.Lens)

A variation of the standard formula:

## FOV = (360/2*PI)2ATAN(1/ZOOM VALUE)

The Blender X Factor is the ratio of the render view SizeX SizeY values.

The default values are SizeX = 320 and SizeY = 256
The ratio of which is 1.25.
Simple really!!

Cheers Stephen