parallax distance

The parallax distance to an object is the distance you get by moving your (single) eye's position by a transverse distance x, measuring the angular displacement θ of the object given that move, and dividing the transverse distance by the angle.

Problem-set problem: You are outside after the rain late in the day and you see a rainbow. What is the parallax distance to the rainbow?

(Thanks to Andrei Gruzinov at NYU.)

perspective

Future problem-set problem: These two images were taken from the same three-space camera position, with the same digital camera. What, physically, was changed about the camera, and why did it have the effect that it did?