The Altair Astro Planet-Killer 685nm Premium IR Pass Filter is designed to deliver sharper lunar and planetary images with Monochrome CCD or CMOS cameras. Unusually for filter of it's type, the Altair Planet Killer has an AR coating to improve contrast.
 
It works by reducing image distortion caused by the atmosphere by passing 685nm and longer IR wavelengths which are less affected by air currents. It also removes background blue skyglow day or night, for very high contrast daytime lunar or planetary imaging.
 
This reduces the blurring effects of  bad seeing for noticeably sharper lunar, planetary or guide star images, even near the horizon. Especially good for CMOS cameras with high infra-red sensitivity like Altair Hypercam and GPCAM mono cameras.
 
See the two exmaple images (click on the thumbnails) to see the drastically improved sharpness and detail on Jupiter and the moon.
 
When used as a luminance filter with planetary RGB filter sets, extremely fine detail is revealed. When imaged in the daytime lunar and planetary objects appear against a dark background. For monochrome imaging of the moon, day or night, the Planet Killer Filter is all you need!
 
Another possible application is for auto guiding at long focal lengths, to reduce the effects of air movement on the guide star. This would theoretically produce better information tracking performance because the guide camera would no longer be "chasing" the seeing (air currents) instead of the mount movements.
 
Advanced AR coatings reduce halo effects and internal reflections.

Premium filter features:

• Batch-tested for consistency.
• High quality dichroic/dielectric coatings.
• Anti-Reflection coating to reduce star-halos .
• UV/IR block for imaging.
• Ultra-flat glass by Schott Germany.
• Precision CNC machined filter cell for strain-free mounting and freedom from tilt.