Announcement Baader Narrowband F

Baader Planetarium H-Alpha Pass Filter
December 7, 2007

In addition to the Baader Narrowband Filters SBIG is pleased to offer a lower cost Baader H-alpha Filter with a wider passband.

The Baader "H-Alpha Pass Filter" has a 35nm passband and a peak transmission of approximately 95%. The same high optical quality and features as the other Baader filters ensures the highest contrast and sharpest images possible. Baader Planetarium filters are made from striae-free substrates, and actually fine optically polished flat to within 1/4 wave p-v over the entire surface, plane parallel to within 30 seconds of arc. This important and unique custom step adds cost - but the result is a filter that maintains the full wavefront quality of the telescope without double images or ghosting, even at high magnifications. Critical to maintaining this level of flatness are Baader's carefully balanced coating designs, which prevent coating surface stresses from warping the substrate. Such high flatness enables Baader filters to be used far in front of the focal plane, ahead of star diagonals. Durability has always been a hallmark of Baader Planetarium. The multi-layer dielectric coatings are plasma assisted and Ion beam hardened using the latest technology (the coatings are harder than the glass substrate itself!). Baader filters withstand repeated real-world exposure to the elements and physical cleaning. Users need not leave their precious filters dull and dust encrusted to avoid cleaning - Baader filters may be used and cleaned without fear. Baader Filters will truly last lifetimes.

Despite the high quality and advanced technology, Baader Planetarium filters are affordable.

H-alpha Pass Filter	Center Wavelength (nm)	Passband Width (nm)	Peak Transmission %	Price 1.25" in cell	Price 50.8mm unmounted
H-alpha	656.3	35	95%	$90	$240