Using filters on the gas giants
Specific colours and wavelengths will enhance your view of Jupiter and Saturn
Filters can be used to enhance both visual and imaging sessions. The Wratten (W) scheme is commonly employed for visual planetary observation, with filters normally identified by ‘W’, followed by a number and sometimes a letter.
Visually, a light blue filter (W38A or W80A) enhances contrast within brighter zones and draws out detail in atmospheric clouds. Light green (W57) and blue (W47) helps to darken brown-hued belts. A W57 light green or a magenta (W30) filter also helps highlight Saturn's rings. Using a W30 filter, meanwhile, will brighten white ovals in Jupiter’s atmosphere.
When imaging, mono camera setups work best for filter work. Full colour images are made by imaging through red, green and blue imaging filters and combining the results. Infrared (IR) pass filters produce high-contrast results, great for showing definition. Some colour cameras have good IR sensitivity and can be used in combination with such filters.
Speciality filters, such as those centred on the methane absorption band (CH4), produce valuable results for Jupiter. Centred on a wavelength of 890nm and with bandpass windows typically less than 15nm across, light is at a premium with this filter making it more suitable for larger instruments. A CH4 filter brightens high-altitude atmospheric features.