Altair 8nm - 540nm Continuous 1.25" solar contrast enhancement filter

IMPORTANT SAFETY INFORMATION: DO NOT USE THIS FILTER FOR DIRECT SOLAR OBSERVATION! It must be used in conjunction with a professional solar filter or a Hershel prism with Max. 0.024% transmission placed BEFORE this filter. For reflecting telescopes, we recommend Baader solarfilm on the front of the telescope, then screw the filter into a filter holder, camera or eyepiece. For refractors, the filter should be placed just in front of the camera or eyepiece with a Hershel prism in place. Do not use this filter without a proper solar pre-filter, as it will permanently damage your eyes or camera.

The Solar Contrast Enhancer works by filtering out UV, IR and visual wavelengths except for a narrow green FHWM band from 8 nm to 540 nm. This greatly increases the contrast of solar features when viewed with the naked eye, in color or with a mono camera, revealing more detail around sunspots and granulation (rapidly developing solar convection cells) in the solar photosphere. Highly recommended for use with Altair Imaging-Ready Hershel Wedge or Baader Solar Film. NOTE: Do not insert the filter before your Hershel prism or it will melt, it must be placed just in front of the camera, and will thread directly into the 1.25" nosepiece of the Altair GPCAM. For Hypercam with 2" bridge you can order a 1.25" bridge or use an Altair magnetic filter holder with 1.25" filter slider.

why is the transmission focused on the 540nm wavelength? 540nm is a very desirable wavelength for imaging and observing the sun. The Solar Contrast Booster filter improves the performance of any telescope optics, such as refractors, Newtonian reflectors, Maksutovs, Dall Kirkhams, Cassegrains and SCTs. It is especially recommended with Frauenhofer achromatic refractors and short focal length ED doubles, as their optimum performance peaks at this green wavelength by design. In fact, not only achromatics, but also most triplet ED and APO refractors traditionally have peak performance at the 540 nm wavelength, where the human eye shows the best sensitivity. 530-540 nm is not only the traditional "design reference wavelength" for most telescope optics, but also that of most high-end interferometry equipment used to configure and optimize telescope lenses. Most monochrome and color CMOS cameras also reach their maximum sensitivity and resolution in green. Color CMOS cameras, in particular, have an RGGB pixel arrangement with two green pixels for every blue and red pixel, which is an obvious increase in resolution. Therefore, isolating this wavelength to capture those fleeting moments of good seeing has many advantages.

Altair Solar Contrast Booster filter specifications:

• 1.25" standard filter thread Aluminum cell
• CWL540nm band 90% transmission FWHM 8nm
• 1.85mm thick λ/4 optical glass, Parallelism (arcsec) 30
• Si02 "hard" coating with UVIR blocking 300-1100nm and anti-reflection coating

Altair Astro and its distributors reserve the right to change product specifications and pricing without notice.