Thanks Rex, Kevin, Cam Simon and Dunk!
Glad you liked it, you can find out more about the camera mod in this thread,
Alternative Way to Mod your Dslr (no glass removed)
It appears to be not quite as an effective as a usual mod is at letting in the Ha, letting if only about half as much. But still, that suits me well, as I am getting a little of that extra Ha colour and detail without terribly mucking up the colours.
Cheers
Jo