2 A B C D E F G H I K L M N O P R S T U V W
Ob Op Or

Object distance

Distance between the object side principal point and the object.
For larger distances, this is about the working distance

Optimal Aperture

F# with the largest possible DOF.
Larger F# reduces the DOF due to diffraction

critical and optimal aperture


orthographic lenses are a type of fisheye lenses

orthographic lenses are also called” hemispherical“or “orthographisch
orthographic lenses use an image mapping function of type
r = f sin \theta

maintains planar illuminance

orthographic angles
weak medium strong max
66 90 120 180


An orthographic / hemispherical fisheye, uses a parallel projection of a hemisphere onto a plane. The resulting image will obviously be circular. The widest view angle is 180 degrees. At +/-90 degrees extreme distortion will occur. Due to this heavy distortion it’s less often used than f-Theta / angular fisheye.

fisheye types