Thanks guys. Especially Mike, for that very detailed explanation
I'll keep saving my pennies and buy a filter wheel and filters and have a crack at it.
Think I'll take the advice and start out with RGB before worrying about recording and adding a L channel.
Best to learn to walk before trying to run
Mike, I might also do what you and others have done and create an 'artifical' L channel using existing R and/or G channels?
Although that sounds a bit tricky.
Many thanks