Astronomy Specialist



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The Antlia IR-pass 685 filter 1.25" 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 sand storms which can encircle the entire planet and covering 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 visible only 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. For instruments with large aperture (more than 150mm), the Antlia IR-pass 850 is preferable to boost the contrast even more.

The tight tolerance of the filter substrate assures a maximum deviance of ±0.05 from specifications making these filters parfocal.

DO NOT LOOK AT THE SUN WITH THE ANTLIA FILTERS. Serious eye damage will occur.


Antlia IR 685 1.25 filter

Passing band > 650 Nm
Glass thickness

2.0 mm ±0.05

Optical flatness

1/4 λ (wavefront)

Surface quality
60/40 (in accordance with US military watch MIL-O-13830)
Glass type
Schott monolithic optical substrate (non glued)


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