The second big gun in the war against light pollution was the purchase of light filters. These have turned out to be a nearly indispensable aid on many subjects, as they will often throw the subject into stark contrast against the sky. I have found that narrowband filters (as opposed to broadband or other) are preferable for most suburban purposes, as they allow the transmission of light from the target object and suppress other wavelengths, including sodium and mercury vapor streetlamps. In my own situation, I get excellent results on the majority of deep space objects with Orion's 2-inch Ultrablock filter (Orion of USA, not the venerable Orion Optics of England!), in combination with a 27 mm TeleVue Panoptic eyepiece, for a magnification of 76x. While I tend to characterize the mainstay and style of the Orion catalog as being primarily aimed toward novice and intermediate "stargazers", the company nevertheless does include some fine products for a more advanced clientele. Broadband filters are also available, and likely to be less expensive. They tend to make the view more agreeable, but generally do not reveal much more than was already apparent before. As with all things, trial and error is always the best way to find out what works best, on what, and for you.
Light filters are not for everything, although on some things they make all the difference between invisibility (or just a ghost of an image), and a strikingly contrasted view, even from dark sky sites. Also, they sometimes help in the search for certain faint deep space objects, as they darken the background sky (although many background stars will disappear from view as well). You might also want to investigate some of the other leading brands of light filter, and namely the much-respected Lumicon brand. I would recommend their UHC filter as very similar in performance to Orion's Ultrablock. Lumicon also markets some interesting variations of the standard narrowband filter, with very specialized usages in mind. (In the confines of suburbia, though, you will need to experiment with these to see if they provide any benefit; this may be marginal, and on only a few subjects.) There are other makes of light pollution filters, of course, with individ ual preference determining which one is best for you, and also available now, light filters for image intensifiers (the subject of the next "big gun"). More in the next section.
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