Hi everybody, Guys I'm a total stranger to physics. I need some help to find the relationship between the major/minor axes of an ellipse and the radius of a sphere in a cone of light. For example, imagine a light source is located at 'h' height from a plane and a sphere(with a radius of 'r') is located at y vertical distance from the source of light and horizontally deviated at x distance from the perpendicular axis of the plane and the source of light. Obviously if the horizontal deviation is zero, then the projection is a circle. But I would like to know the relationship of the ellipse to the radius of the sphere when horizontal deviation is not zero.