Martin,
In that circumstance I'd be at f1.4 with a 50mm lens or 2.8 on the 70-200, so the b.g would be blurred and then optimized the foreground subjects with curves and sharpening in PS. I might darken the b.g. a tad.
So how would you take those subjects. Would you manouver to have the b.g. clear or just wait for the clear opportunity to get it right and forgo other "opportunities".
Regards,
Asher
I rarely if ever shoot kids because I have trouble getting down low enough (horrible knees). But yes, you need to be eye-level, and use a wide open lens to isolate the subject from the busy b/g. To keep it spontaneous you may not be able to wait for empty b/g. That's why you want to shoot at f/1.4. A 35mm lens would be great. You have to watch out for super bright light in the b/g which will also ruin the shot even if the b/g is OOF.
Yes, there are ways to shoot down on kids and make it work sometimes. But unless handled perfectly it doesn't often look attractive.
This is also a good case to make for fast primes over zoom kit lenses. Many kit lenses just aren't fast enough.
And of course, this is just an opinion based on my sensibilities. Styles vary!