Distance affects power Halving the distance between the ash and subject will increase its strength by four times – or two stops – in accordance with the inverse square law.
Distance and quality Changing the distance of the light also changes its size in relation to the subject – the further away it is, the harder the quality of light.
Watch for fall-off The fall-off of a flash is the difference in strength across the subject, and it will be more pronounced if the light is in very close.
Look to the catchlights If you want to see how other portrait photographers have lit their photos, the catchlights in the subject’s eyes can indicate the positioning, quantity and type of light used.
Bounce the flash As well as using modifiers like umbrellas and softboxes, remember that you can also soften and diffuse the light by bouncing it off the walls or ceiling.
Shutter speed and flash Shutter speed has no bearing on the ash exposure, only on the influence of the ambient light. If in doubt, stick to 1/200sec.
Diffusion needs more power Any modifier placed between our light source and the subject – like an umbrella or softbox – will weaken the output, so increase the power accordingly.
Feather the light Try feathering the light by angling it across the front of the subject rather than directly at them; this gives an attractive ‘wrap-around’ quality.
Recycle after lowering output If you lower the output, hit the test button to recycle the flash as it may still be primed for the previous higher power setting.
Bring lights in close Bringing the lights in close will make them very large in relation to the subject and therefore produce softer, more flattering light.