Baader Planetarium, long a source of premium astronomy accessories, now expands its line of imaging filters to include a set of four narrowband filters. Starting at $495 for a set of 1¼-inch mounted Hα, Hβ, O III, and S II filters with 7- to 8.5-nm bandpasses, these multilayer dielectric filters are hardened so that users will be unlikely to damage the coating when they're cleaning off dust. Each filter is made from striae-free glass polished to a surface accuracy of ¼ wave to guarantee that they won't degrade the image quality of your telescope. Each filter is available separately, and they're also offered in 50.8-mm diameters without cells.

Baader Planetarium
www.baader-planetarium.com

Available in the US from:
Santa Barbara Instrument Group
147-A Castilian Dr.
Santa Barbara, CA 93117
805-571-7244; www.sbig.com

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