Telescope Reviews: Re: Best light pollution filters?

Several companies make 2" to 1.25" adapters that are threaded for filters. I have two, but I'm not sure of the brands. One might be Antares. I think this is pretty common on modern adapters, but certainly not on all...

GTO probably makes a threaded adapter-- I have a 2" focuser extension tube from them that is threaded for filters. GTO eyepieces and accessories are carried by Hands On Optics.

So, I'd get 2" filters along with a threaded adapter.

I currently have an 1.25" Orion Skyglow, 1.25" Celestron UHC/LPR,2" Lumicon UHC, and 2" Lumicon OIII filters.

The Orion and Celstron filters are nearly identical, and provide very mild increase in contrast, but they do make a difference in objects that are otherwise nearly or totally invisible, while not dimming stars too much (they do turn green, though). These are my least used filters. They're 1.25". I don't use the Orion any more. I needed 2 matching filters for my binocular telescope (hence 1.25"). I only got them because they're much cheaper, and I had to buy 2. I'd have preferred to get 2 Lumicon UHC filters.

The Lumicon UHC filter is probably the nicest most usefull all around filter: great increase in contrast without too much star dimming. Useable on all apertures. Get's dim at smaller apertures, but still usable.

The Lumicon OIII filter is astounding in it's ability to provide tremendous contrast in emission nebula, but the star field is very suppressed. This is my most used filter. Things get really dim below 6" aperture.

I've used the UHC and OII lumicon filters with my 70mm Pronto on the North American nebula. While the OIII worked, it was really dim (but not visible without it). The UHC worked too, but because everything in the field got brighter, it didn't really make the nebula easier to see.

So: I think the OIII is the best filter for contrast, especially for larger than 6" apertures. If you want one filter that works well at nearly all apertures and works nearly as well as the OIII, then I'd get the UHC.

None of these help with galaxies, by the way. (The orion and celestron broadbands might help a very little). DGM Optics carries filters that they say are expressly for galaxies, but I haven't tried one...

Kerry

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Kerry

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