It is not an easy object! I found it to be surprisingly large. If I remember rightly the first time I saw it (in a 10" scope from a
very dark site), I was using 70x with about a 40 arc-minute fov. It is several arc-minutes across.
Generally it is hard even with an 18" scope. A number of experienced friends have never seen it, even in an 18" scope, because it is basically dark on slightly less dark, with very little contrast to make even the edges stand out. When I first saw it in the 10" it was a bit of a revelation: because I realised that I had been looking at it, but not seeing it for a couple of minutes!
I think you would need to be fully dark adapted, and at a site with an SQM reading of better than 21.6. You also need to get Alnitak out of the field of view.
I have never used an H-beta filter, and although I understand it does help, it apparently isn't much use for many objects.
I have seen it through a 30" scope: no filter needed then(!), and you could see details within the dark areas. Amazing!
Good luck, but don't expect anything like the photos, unless you are using a 30" scope or bigger!
- Dean
