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High Point #21 Orange Filter - 2" - 21F2


High Point #21 Orange Filter - 2"

This High Point 2" Colored Filter has a Wratten number of #21, which is Orange with a transmission of 46%. An orange filter will help with daytime observations of Venus and Mercury by darkening the blue sky. When observing Jupiter and Saturn, you can expect an orange filter to help you study features that have a bluish hue. Saturn's bands and Jupiter's belt structure will be improved, and the beautiful Jovian festoons and polar regions will be enhanced. Mars will also benefit from a red filter in several ways. It will reduce the light from blue and green areas, which darkens the maria, oases, and canal markings while lightening desert regions that are orangish in color. The 21 filter will also improve the definition of a comet's head and dust tail when used with 11" telescopes or larger.

Colored filters can be an invaluable aid in lunar and planetary observing. They reduce glare and light scattering, increase contrast through selective filtration, increase definition and resolution, reduce irradiation and lessen eye fatigue.

All of High Point's 2" colored filters are made of high quality, solid plane parallel glass that has been anti-reflection coated to prevent glare and ghosting. They have a full 43mm clear aperture, and are mounted in a black anodized aluminum cell that is threaded on both sides to fit most 2" eyepieces and stack with other High Point 2" filters.

Please note that the effectiveness of this filter depends on several factors, including the aperture and focal length of your telescope, the magnification being used, and the seeing conditions at the time. Remember that filters lower the amount of light that reaches your eye. You'll need an aperture of at least 8 inches for dark filters such as the #47 Violet, with only 3% transmission, the #29 Deep Red with 6% transmission, or the #38A Blue with 17% transmission.