Thanks Ken and Phillip for your replies and clarification. It obviously makes sense.
Ken that’s a very interesting combo re the CaK side of things. This where the whole question got started with looking for my L filter as a UV/IR block in my old RGB filter set, which I couldn’t find. I think that L filter equates to today’s L2.
Its been an interesting journey which has revealed a number of options. Thanks for your ideas and views.
