Figure 1.  The modulation transfer function (mtf) of image contrast at different spatial frequencies by the mechano-optical device. Also shown is the mtf of a Nikkor 50 mm lens and a glass marble. The compound eye of bees can resolve spatial frequencies of about 0.25 cycles/degree, showing that the ray selectors provide an accurate representation of the frontal foveal region of an insect’s eye (Srinivasan and Lehrer 1988) where the ommatidia are approximately parallel to each other. Adapted from Dyer and Williams (2005).