Skyfog around Mag 20/sq arc-sec, say, around Visual Lim Mag 5.5 to 6 at zenith. Not quite a pristine dark site, but not horrible either. Consequently I used a Hutech LPS "Front-Filter", a pop-in, hoping for better signal. Unfortunately even 93 minutes' exposure at f2.8 hardly reveals much nebulosity, top-left image, displayed after stacking and contrast-stretching. A similar integration time through an Astronomik 6nm H-alpha "clip" filter, also a pop-in, does a much better job, though, still rather noisy, top-right image. Perhaps this nebula is indeed faint... Anyway, combining the two, using "lighten" mode produced the bottom image. Kenko Skymemo unguided. NB the Astronomik "clip" filter fits both my Canon 40D and 20D. My Hutech IDAS LPS-P2 filter requires different frames for the 40D and 20D. I had to buy the frame for the 40D separately from Hutech. Conclusions? The Astronomik "clip" frames are a great boon for those with more than one Canon DSLR, and the 6nm Ha filter is well behaved, no ghosting to complain about, etc. It even came with measurement data indicating transmission efficiency at Ha, 92%.