Considering the appropriate filtering method is always a challenge for solar photography. First of all, the filter has to be safe for the observer and the equipment. Obtaining high-resoluting images with good contrast is the goal of any observer. Depending on the optics (telescope or refractor), using always the same filter would not systematically lead to the optimal images. On the market, the main front filters like the famous AstroSolar, the metallic filters or the less known Marumi (DHG ND-100000) are available. They all offer a safe solution. However, in term of resolution and contrast, they are not always compatible with the full potential of the optics. A Herschel wedge is also a very good solution, but quite expensive and almost only compatible with a refractor. By the way, this solution has been tested on April 21 & 24, 2021.
The proposed setup here is very simple and highly efficient. The solution is based on two filters. As main filter, which is put in the front of the optics, is a classical ND1000 (or ND3.0) photographic absorber. As an example available in 77mm diameter: Hoya ProND1000. It is mandatory to consider a secondary filter like a narrowband oxygen III (OIII) with a bandwidth of about 12nm or less. Such filters are proposed in 1.25″ or 2″ diameter through different vendors. For a visual use of the setup and not only with image sensors, adding and IR-cut filter would be highly recommended.
Compared to an AstroSolar foil or a conventional metallic filter, the solution presented here is offering the following additional advantages:· Solar images taken with this new setup
· Setup details
