Thanks for your welcomes and helpful comments.
Re filters, we have a Lumicon UHC filter -and the sticker on its box mentions both OIII and HBeta, so it looks like it filters in both?? I have just come in from a great little observing session using it on the Omega, Trifid and Lagoon Nebulae ... just brilliant ... and I'm verrrry happy with my dob ...
