Ocular plugin FOV for wide angle lenses

[Khalid AlAjaji]

This a feature request for ocular plugin to add support for wide field short focal lengths lenses.

If I define a wide field angle lens (short focal length) as a telescope, the rectangular red box will not represent an accurate FOV for the sensor defined. The reason for that, I think, is that the plugin uses an approximation formula that is good for long focal lenses like telescopes. it states in ccd.hpp:
/**
   * The formula for this calculation comes from the Yerkes observatory.
   * fov degrees = 2PI/360degrees * chipDimension mm / telescope FL mm
   */

May be the exact formula will be good for both long and short focal lengths, see: http://en.wikipedia.org/wiki/Angle_of_view

Thanks