Many thanks, Brian & Alan. I too have a Sony, and they are Sony 2x I have seen on Amazon, so I'm encouraged by what you've said. I've been told (in a camera shop) that you have to zoom in before adding the converter, otherwise you get a 'halo' effect. Is this right? I can't see how to find a bird at 40x mag! And it would probably have gone by then anyway! If this 'halo' effect does happen, how much difference does it make to quality etc?
I agree about having a tri /monopod, I just haven't used mine much as it seems to reduce freedom of movement - I tend to hold my breath as much as possible while filming!! So if you see someone with a camcorder and bright purple face- it's probably me!!