You can try continuous flash to check for shadows on the subject before shooting.
The flash will fire for two seconds at a rate of 40 flashes per second.
Press the TTL/M/Test button to turn on the modeling-flash
Each time the TTL/M/Test button is pressed to change the TTL and M lamp
be sure to check that the appropriate lamp is on. (See page 33 for the display
Press the TEST button (test/modeling flash button) .
Do not press the shutter button while the flash is in use.
The strength of shadows will differ from that during actual photography.
When using the flash in a bright place or outdoors or when using a bounce
flash, shadows are lighter so verification is more difficult.