(let* ((d-width (* 2 object-distance (tan (degrees->radians (/ aov-width 2)))))
(d-height (* 2 object-distance (tan (degrees->radians (/ aov-height 2)))))
(d-diagonal (* 2 object-distance (tan (degrees->radians (/ aov-diagonal 2))))))
(let* ((d-width (* 2 object-distance (tan (degrees->radians (/ aov-width 2)))))
(d-height (* 2 object-distance (tan (degrees->radians (/ aov-height 2)))))
(d-diagonal (* 2 object-distance (tan (degrees->radians (/ aov-diagonal 2))))))