The New Baader Planetarium Calcium K-Line Filter makes imaging of the sun in K-Line accessible to anyone with a telescope and digital camera or webcam. Baader's innovative double-stacked filter uses sophisticated coatings to produce a sharp 8nm wide bandpass, centered at 395nm. This bandpass provides ample contrast for high-resolution imaging of super granulation, flares, and other features that are prominent in CaK. Unlike small, dedicated, and expensive CaK telescopes, the Baader K-Line filter works with with your existing telescope - at a small fraction of the cost. The Baader CaK may be used with virtually any telescope, of any aperture - Newtonian, SCT, Refractor, etc.
The Baader K-Line Filter is simply used just like any standard 1.25" thread-on eyepiece filter. It may be attached to an eyepiece for projection imaging (see Digital Photography for camera projection adapters and Digital T-Rings), or directly to a camera's nosepiece (ie, T2-14) for prime-focus . In addition, an objective pre-filter must be used at the telescope's entrance to reduce the energy that reaches the filter. For this purpose, a 200mm x 290mm (8x11inch) sheet of Baader's renowned AstroSolar Photo Film (Photo ND=3.8) is provided with each K-Line filter.
The Herschel Safety Wedge Solar Prism may also be used as the energy rejection filter (in place of the AstroSolar Photo Film). This will provide the absolute highest quality solar images possible in CaK.
Please note: The Baader K-Line filter is intended Only for imaging. It is not suitable for safe visual observation (the UV levels may pose an eye safety risk from prolonged observations). Due to the eye's low sensitivity and very poor resolving ability at 395nm, solar features in CaK are generally invisible for most observers - even through multi-thousand dollar sub-angstrom dedicated CaK etalons and telescopes. All of these instruments are intended primarily for imaging.