Backyard Calcium K
Filters
Backyard Calcium K filters range from a diagonal inserted
into a telescope, rear mounted filter or a complete
telescope system. All three designs do the same thing, block
unwanted light and pass the Calcium K emission line.
Diagonal systems as shown above take the instrument
light from the telescope and filter it through
infrared/anti-reflection blockers, Induced Transmission
Filters (ITF) and and a narrowband blocker.
An etalon is not used in the system.
The final
bandpass is around 2.4A compared to 1A or below for a
hydrogen-alpha system.
Popular Calcium K line filers are made by:
Lunt Solar Systems
http://www.luntsolarsystems.com/
Baader Calcium K Filter
The first "stacked" 1.25" filter
for digital cameras and webcams. Used for taking images of the sun's
Calcium spectral line. The filter permits the 393nm and 396nm lines,
resulting in an intensely blue image. The filter is particularly
suited for reflecting telescopes. If used with a refractor the
telescope should have a good contrast in the blue spectral region.
http://www.telescope-service.com/baader/solar/solar.html#BaKa1
DayStar
Calcium K and H Filters
http://www.daystarfilters.com/calcium.shtml
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