Craig,
Your OII filter cuts out a bucket load of visual light so it will knock out loads of light pollution as well as visible light from galaxies. If your looking to kill light pollution you;d be better off with some sort of CLS filter. A CLS filter will pass OIII and Hb in the visible band as well as upper red band Ha and sulphur.
I attached a couple of responce curves from astronomiks. The grey curve is human visible. These sort of filters are also known as deep sky, sky light, LPS and a few other names by different makers. They are designed to reduce light pollution.
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Nothing can substitute a dark site
