H- Alpha & Calcium K Filters

H-Alpha and Calcium K Bandpass solar filters make up the majority of specialized solar filters. Of the two, H-Alpha is the more common and Calcium-K the more specialized. H-Alpha solar filters will produce excellent views and images of solar prominences, solar flares, solar corona, and other details on the sun's surface. H-alpha filters produce images in a natural pallet that veers between orange, red, and yellow in varying shades. Calcium-K is a more specialized wavelength that emphasizes areas with strong magnetic fields and displays the sun in a striking pallet of purple and blue. Both types of solar filters come in a variety of sizes and variants, and we have provided a convenient solar filter cheat sheet to tell you which filters will fit to which telescopes. Solar safety is a priority in every solar product sold at OPT, and we urge you to carefully follow the procedures listed in any instructions included with any solar product for your own wellbeing. 

 

                                                              

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Between the two of them, H-Alpha and Calcium K Bandpass solar filters make up the majority of specialized solar filters. Of the two, H-Alpha is the more common and Calcium-K the more specialized and unusual. H-Alpha solar filters will produce excellent views and images of solar prominences, solar flares, solar corona, and other unusual details on the suns surface. H-alpha filters produce images in a natural pallet that veers between orange, red, and yellow in varying shades. Calcium-K is a more specialized wavelength that emphasizes areas with strong magnetic fields and displays the sun in a striking pallet of purple and blue. Both of these types of solar filter come in a variety of sizes and variants, and we have provided a convenient cheat sheet to tell you which filters will fit to which telescopes. Solar safety is a priority in every solar product sold at OPT, and we urge you to carefully follow the procedures listed in any instructions included with any solar product for your own wellbeing. 

If you're interested in viewing solar prominences, solar flares, solar corona, and other unusual details using your exisiting telescope, then a Solar Hydrogen-Alpha (H-alpha) Filter is a perfect choice.  These high quality filters are designed for blocking all light except for the h-alpha wave length.  This is an important emission line for solar observation, as the Sun's surface layer contains a high proportion of hydrogen.  The H-alpha filter allows safe observation of the entire solar disc, providing superb views of prominences, chromosphere, and surface details such as sunspots, plagues, flares, filaments, and granulation.  They are meant for both visual observing and astrophotography.

An H-Alpha filter for solar viewing is not to be confused with a hydrogen-alpha filter meant for astronomy.  A solar Ha filter is designed for a specific bandpass and is created with multiple layers of vacuum deposited coatings.  It also corresponds with the aperture of the equipment being used.  H-Alpha filters are traditionally designed for a refractor telescope and work in conjunction with a blocking (or energy rejection) filter that is also based upon the focal length of the telescope.  The general rule of thumb is to first add 100 to the blocking filter aperture and then keep your telescope's focal length within that limit.  For example, a 6mm blocking filter would be best for telescopes with 600mm or shorter focal length.

Because the Sun is dynamic, fast-moving events will often place the bandpass of light just above or below a specific “setting”.  For that reason, a solar h-alpha filter comes with a device, or “tuner”, that allows the filter to be shifted slightly to capture the event.  This is also the purpose of an etalon.  With H-alpha solar viewing, the narrower the bandpass of the filter, the greater the details can be observed.  To achieve this, filters can be “stacked”, which means placing two filters on top of each other to further fine-tune your view.  Double stacking is particularly popular for photography.