The American sun filter manufacturer DayStar revolutionised sun observations with its QUARK series. For a comparatively low price you can now use a refracting telescope with a small aperture for watching the Sun in a defined spectral line – this is no more complicated than plugging an eyepiece into a diagonal mirror.
DayStar have now extended their QUARK series by a model to watch the Sun in a spectral line of the chemical element calcium. With the DayStar QUARK Calcium-H-line sun filter you can watch the sun at a wave length of 397 nanometres – or perhaps not: Not everyone is able to notice such short-wave light.
However, with a planet camera this short-wave radiation can be recorded without any problems. Corresponding tests were undertaken by our colleague Bernd Gährken:
For this photo 4 images were combined. In addition to the QUARK Calcium-H-line, an Omegon photoscope with 1.6x Barlow and a planet camera were used. The scope of delivery includes adapters for 1.25″ and 2″ focusers. The Calcium filter works without telecentrics and requires an optical path of 6.2 centimetres. With many optics the focus cannot be reached directly. We therefore recommend also ordering the reasonably priced path corrector. It can be screwed directly into the QUARK filter. In terms of cameras, we specifically recommend the Mono Guider from Touptek or the planet cameras from ZWOptical. When photographing a tight spectral range, the complete resolution of the sensor can only be utilised when using a black-and-white camera (“mono”).
Unfortunately there were no sunspots on the sun when this photo was taken. This exemplary image provided by the manufacturer shows what sunspots in the light of the Calcium-H-line look like.
Photographic data for this image can be found on the product page, QUARK Calcium-H-line.
Observing the sun is a fascinating alternative or an additional challenge for stargazers.