These filters are threaded to fit standard 1.25-inch eyepieces and the Cassini Four (4) Slot Filter Wheel. The astronomical filters generally work by blocking a specific part of the color spectrum making the object more visible or defined. Filters can be used to increase contrast and enhance the details of the Moon and planets. Each of the 13 filters comes with it's own plastic storage case.

Light Yellow (83% transmission) Used to enhance detail in red and orange features in the belts of Jupiter. Is useful for increasing mare contrast on Mars and improving disc resolution of Uranus and Neptune with larger telescopes. Can be used to enhance lunar detail also.
Yellow-Green (78% transmission) Excellent for bringing out surface details on Jupiter.
Darkens the mare regions on Mars.
Yellow (74% transmission) Enhances red and orange features of Jupiter and Saturn, while blocking blue and green wavelengths. It also lightens red and orange features on Mars, while reducing, the transmission of blue and green areas. This filter increases the contrast between the two. Also enhances the blue clouds in the Martian atmosphere. Can also be used to increase contrast in lunar features with telescopes of 150mm aperture and larger.
Orange (46% transmission) Reduces transmission of blue and green wavelengths, thus increasing the contrast between these areas and red or yellow or orange areas. Works very well with Mars. Sharpens the boundaries between these areas on the planet's surface and can sharpen the contrast in the belts of Jupiter also enhancing the Great Red Spot. Has slightly more contrast than the Wratten #15.
Light Red (25% transmission) A popular filter for use when observing Mars, Jupiter, and Saturn. Due to the lower light transmission of this filter, it is best used with telescopes larger than 130mm aperture. It performs many of the same functions as the #21 and the #15 but with somewhat more contrast. Can be a useful filter for daylight observations of Mercury and Venus. improving contrast between these planets and the pale blue sky.
Red (14% transmission) The #25A filter strongly blocks the transmission of blue and green wavelengths which results in very sharply defined contrast between the cloud formations and the lighter hue features of Jupiter. Also quite useful for improving definition of the Martian polar ice caps and darker mare surface regions.
Dark Blue (17% transmission) Very good for use on Jupiter because it strongly rejects red and orange wavelengths in the belts and in the Great Red Spot, thus increasing contrast. It works well on Martian surface phenomena, like dust storms, and increases contrast in the rings of Saturn. Most suitable for Venus given its low light transmission and readily increases contrast of subtle cloud markings.
Violet (3% transmission) Strongly rejects red, yellow, and green wavelengths, making it suitable to use on the Martian polar ice caps. It is the best filter for observations of Venus due to its low light transmission and ability to enhance upper atmosphere phenomena. Also can be used for enhancing lunar detail. Presents interesting views of Jupiter and its satellites.
Light Green (53% transmission) Very good for observing Martian polar ice caps and yellow tinted dust storms on the planet's surface. Also increases the contrast of the red and blue regions in Jupiter's atmosphere and cloud belts.
Green (24% transmission) Strongly rejects red and blue wavelengths increasing their contrast on the lighter regions of Jupiter's cloud tops. Useful for enhancing the cloud belts and polar regions of Saturn. Great for increasing contrast in polar ice caps of Mars and does a reasonable job at improving contrast of atmospheric features on Venus.
Blue (30% transmission) A magnificent all-round filter. Perhaps the best economical filter for studying planetary detail of Jupiter and Saturn. Enhances contrast of festoons and other disturbances in Jupiter's cloud belts, along with detail of the Great Red Spot. Works great with Saturn revealing terrific detail in its belts and polar features. Can be useful for lunar observations.
Light Blue (73% transmission) Another outstanding performer like the #80A and works well with Jupiter, Mars, Saturn and the Moon. Its pale blue colour enhances low contrast areas and avoids significant reduction of overall light level at the same time.
Neutral Density (0.9 density, 13% transmission) The neutral density filter transmits light uniformly across the entire visible spectrum making it an excellent tool for glare reduction and studying bright localised lunar surface regions around times of full Moon. Suitable also to improve contrast.



Cassini 1.25" 13 Pc. Astronomical Filter Set

M.S.R.P $125.95


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