Planetary Filters

Colour Filters and What Each One Reveals

Planetary filters follow the Wratten numbering system. Each passes a colour band and suppresses others, raising contrast for features that differ in colour from their surroundings.

• Wratten 21 orange and 23A light red: Darken the blue-grey Martian surface markings against the ochre background, and sharpen the polar caps. The most useful Mars filters at apertures of 150 mm and up.
• Wratten 80A blue: Enhances Jupiter's belt structure and the Great Red Spot boundary, and reveals Saturn's cloud banding, which is subtle in unfiltered views.
• Wratten 12 or 15 yellow: Reduces glare on Venus and the Moon while lifting contrast on Jupiter's zones, with less light loss than deeper colours.
• Wratten 58 green: Brings out Jupiter's polar regions and the contrast between Martian dust and surface, though it dims the view noticeably.
• Wratten 47 violet: A specialist filter showing Venusian cloud structure, which is invisible in white light and requires substantial aperture.
• Neutral density and polarizers: Reduce lunar brightness without altering colour, and variable polarizers let you tune the level continuously.

Why Choose David Astro for Planetary Filters

A deep colour filter in a small telescope removes more light than it gains in contrast, and the result is disappointing.

• Aperture-matched recommendations: Below about 150 mm, stick to lighter filters — yellow and light blue — since deep red and violet leave too little light to be useful.
• Target-based selection: We suggest filters for the planets you actually observe rather than selling a full Wratten set, most of which sits unused.
• Barrel size confirmed: We match 1.25 inch or 2 inch to your eyepiece set before you order.
• Authorized dealer: Genuine filters with manufacturer warranty, held in Canadian stock.
• Ships from Canada: No duties or brokerage fees for Canadian orders.

Planetary Filters in Canada — Frequently Asked Questions

Which filter should I buy first?

A light blue such as 80A is the most generally useful, improving Jupiter and Saturn detail. Add an orange for Mars when it approaches opposition, which is when it is worth observing seriously.

Do colour filters work with a small telescope?

Light filters do. Deep colours remove so much light that an 80 mm telescope gives a dim, unrewarding view. Aperture of 150 mm and up opens up the full range.

Are planetary filters useful for imaging?

For monochrome planetary imaging, yes, and RGB filters are used to build colour images. For colour cameras they are generally unnecessary since the Bayer array already separates colour.

What about a Moon filter?

A variable polarizer is the better choice over a fixed neutral density, since lunar brightness changes dramatically with phase and a variable filter lets you tune it rather than swapping.

Chasing planetary detail?

Tell us your aperture and target planets and we will recommend a short, useful set. Authorized dealer, Canadian stock.