Crikey, I'm blushing!!
Firstly, I hardly ever use flash with the Bigma. I use it often with the Sigma 150mm Macro, but your normally too far away for it to be effective with the Bigma.
I always shoot in RAW, and use either the Raw converter in Photoshop CS2, or Rawshooter Pro. I generally use Rawshooter Pro. I just convert to jpeg and then do the balancing of levels etc in photoshop. I used to convert to tiff first, but I don't bother with that when doing images for the web. I can always re-use the RAW file if I want to print.
As for field training, I don't regard myself as good enough for that..I'd gladly go on one from Kev Lewis for example..(hint hint Kev!!)
If ever your near Nottingham and wish to go somewhere around here, I'd be glad to go with you.
