Sony HVL-F36AM Operating Instructions Manual page 24

Adjusting bounce angle
Simultaneously using direct light and bounced light from the flash
produces uneven lighting. Determine the bounce angle with respect to the
distance to the reflective surface, the distance from the camera to the
subject, the focal length of the lens etc.
Correct
Incorrect
Determine the angle in relation to the following table.
24
Focal length of lens
70 mm minimum
28 - 70 mm
28 mm maximum
Bounce angle
45°
60°
75°, 90°