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Code: DS-IR685

Optolong - 685nm IR Pass filter 1.25 inch

Ideal dialectically coated filter for the reception of the moon and planets, notably Mars, with telescopes from 6" (150mm) aperture.

The filter only allows infrared light with wavelengths of more than 685 nm to pass and is commonlu used by serious planetary imagers to help improve the effects of atmospheric turbulaence (the seeing) when using monochrome cameras. In this wavelength range the effects of seeing are significantly lower than in the visible spectrum of the human eye. This allows much sharper images than are usually obtained from your device and location. Another advantage is that the sky background of advanced dawn is dark and so the filter even allows photography of the planets and the moon at daylight.

This filter cuts off the visible part of the spectrum and allows the light of wavelengths longer than around 685nm to pass. Due to this behaviour the part of the spectrum that is most sensitive to bad seeing is rejected. This feature means potentially improved outcome when imaging planets and the moon. The image is more steady than seen in visible light with nearly identical exposure times.

-Darkens the background during twilight.
-Imaging of bright planets, stars and comets by day.
-Imaging of young stars in dust clouds and stellar nurseries.
-Video imaging (Planets and Moon): Very good, rejects problems with seeing

-More than 98% transmission for wavelengths of 685nm out to and beyond 1 micron
-Blocks wavelengths up to approx 660nm
-Parfocal with other OPTOLONG filters
-Glass thickness: 2mm
-Diffraction limited, the filter will not reduce the optical performance of your telescope!
-Includes a high-quality long lasting filter box
-Seated Cell height: 5.1mm



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