Astronomy Specialist



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The Optolong IR-pass filter is designed to boost the contrast in planetary imaging as the infrared radiation is less affected by the atmospheric turbulence (seeing). All planets will appear sharper with the highest possible contrast. 

Mercury will reveal its faint details only with an IR-pass filter. This filter is particularly useful for daytime observations as it darkens the background of the daylight.

Venus can show details on its clouds, especially if combined with the Antlia UV Venus filter.

Mars is the planet that benefits the most by the use of this filter showing many more details in the infrared than in visible light. Especially during sandstorms which can encircle the entire planet and cover features, the IR-pass filter works like a see through.

Jupiter appears much more detailed and sharper with the IR-pass filter. Turbulence on the bands, minor vortexes and ultra thin details are only visible at this wavelength.

Saturn offers its maximum sharpness in infrared and in larger apertures, this filter helps to reveal the Encke division.

Uranus and Neptune are distant and without any high contrast details. Only the IR-pass filters can produce interesting pictures.

The human eye is not sensitive to infrared light so this filter is specifically designed for cameras combined with medium or large telescopes. 


The interferential coating is deposited on the substrate using electron-beam gun evaporation with ion-assisted deposition coating technology. This increases the filter durability and resistance to scratching, as well as stability of the CWL (central wavelength). The planetary rotation system offers precision and homogeneity of the coatings ensuring high transmission of the pass-band and high optical density off-band.

WARNING: Optolong filters are not designed for sun observations. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTERS. You could become BLIND if you fail to observe the warning.

    Passing band Infrared pass
    Glass thickness

    2.0 mm 

    Optical flatness

    1/4 λ (wavefront)

    Band-pass transmission 95%
    Coating Fully-multi coated
    Surface quality
    60/40 (in accordance with US military watch MIL-O-13830)
    Parallelism 30"
    Glass type
    Schott monolithic optical substrate (non glued)
    Available sizes 1.25", 2"

    Optolong filter box


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