Sony HVL-F42AM Operating Instructions Manual page 30

Adjusting bounce angle
Simultaneously using direct light and bounced light from the flash unit 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
When the flash is bounced upwards
Determine the angle in relation to the following table.
Focal length of lens
Bouncing to Left and Right
Rotating the flash by 90° to bounce light sideways is recommended. If an angle of
less than 90° is used, care should be taken to ensure that direct light from the flash
unit does not illuminate the subject.
30
GB
70 mm minimum
28 - 70 mm
28 mm maximum
Bounce angle
45°
60°
75°, 90°