This accessory from the QUARK series enables you to make solar observations in the calcium H-line. Like every QUARK filter, it is simply plugged into the focusers of the telescope.
Please note: The QUARK Calcium H-Line solar filter should only be used in conjunction with refractors (refracting telescopes) up to a maximum aperture of 150 millimetres. From an aperture of 80 millimetres, a UV/IR blockfilter should be used, but it must still be permeable to the light of the Calcium H-Line (see "Recommended accessories"). The refractor should not have any optical elements downstream of the front lens, as high temperatures occur near the focal point - nomen est omen - which damage these elements. So please do not use flatteners, barlow lenses or similar.
The manufacturer DayStar recommends refractors with a focal ratio of f/8 to f/15, for example:
With a longer focal length, the image becomes darker but more contrasty.
The two spectral lines Calcium-K (CaK) and Calcium-H (CaH) are similarly important in scientific solar observation as the H-alpha line of hydrogen. The two calcium lines have wavelengths of less than 400 nanometres. Here, the sensitivity of the human eye decreases noticeably with age. Filter manufacturers therefore concentrate on the shorter CaK wavelength and recommend purely photographic observation, as the CCD chip is sensitive enough.
The Calcium-QUARK is designed for the CaH line. At 397 nanometres, this has a slightly longer wavelength than the CaK line (393nm). According to the manufacturer, this colour is still visible to most people, so that the Calcium-QUARK is also suitable for visual observation.
As with H-alpha light, you can observe the sun's chromosphere in calcium light. The image on the right gives an impression. Prominences are also recognisable in the light of the calcium ions. Due to their low brightness, however, they are mainly photographic.
