DGM Optics NPB Narrow Pass Band Nebula Filter

3.0 No Bright Stars Please...

Really enhances nebula detail, works great against light pollution.

Red "ghosting", dims out faint stars.

I bought this filter because I live right outside the Houston city limits under some severe light pollution. Overall, I thought this filter did its job well. In my 8 and 12 inch Dobsonians, it almost doubles the size of the Orion Nebula and really brings out the details. However, as expected, the decreased light can fade out the dimmer stars. For instance, I can often see the E and F stars in the Trapezium without the filter, but with it in I can see only the four main stars.

The filter is also great for picking out nebulas in my light polluted skies. It's a lot of trouble for me to find the Eagle and Dumbell nebulas without the filter, but they really stand out with it in.

This filter does have one big problem however. I find that bright stars tend to have issues with ghosting (red shadows of the star next to the main image). On dimmer stars, the main image and shadow are blended more together and the star simply looks purple to me. I find this image of purple stars and bright ghosted stars very distracting (artificial looking). In fact, I now use this filter mainly for finding nebula rather than viewing them.

Overall, I'm only going to give this filter an "average" rating because I can't stand the ghosting and dim views. However, I'm still going to recommend it because I think every astronomer with an 8" or greater scope should have a narrow pass band filter. I've found nebula and seen detail with it that I could not have seen otherwise.