When shooting an event, you would usually use a somewhat wider lens (a 35mm, say, or a 24-70) and bounce the flash behind you, upward – you have read this here many times.
But when you take candid shots with a longer lens, behind you does not always work: to get the righ angle of attach of the light to your subject, you have to bounce forward. I have mentioned this here too, but let me illustrate with an example.
Straight on is not good: hard shadows and “deer in the headlight” eyes. Even when combined with lots of ambient light to minimize this effect, it’s still not great:
But sometimes, bouncing behind is just too far. When you are far away, 45 degrees up but forward is better – but the problem is that some of the light goes straight to the subject:
See the hard shadow under the chin, in the picture above? Especially if there is a wall behind the subject this will be unacceptable.
So then you block the direct path with a bit of a flag (your hand right in front, or a reflector with the black side used to eat up the forward light – so it sticks jus a little above the flash head. You now get this:
So.. when you take flash pictures, just as in yesterday’s lesson: remember where the light goes!