[Allan]

Hi Mark,

Just remember that when you put a filter in your eyepiece you're cutting down on the light you see, because that's the job of the filter. I'm not sure how well an OIII would work in an 8" because it is a 'line filter' which means it only lets a relatively small amount of light through, and in an 8" the image may appear too dark.

I think you should start off with a UHC filter. They still filter out some light, so the image will be a little darker, but not as much as the OIII so should work nicely in your 8". A UHC will really improve the contrast on nebula. After you have used one for a while you could consider an OIII then.

Don't bother with a Ha or Hb for visual use. Also I think the sky glow type of broadband filters are a waste of time as well. The UHC and OIII filters are definitely the workhorse filters for nebula use. I use both in my 12" and the Eta Carinae nebula viewed with my OIII blows me away every time.