Large aperture scope are often claimed not useful for high resolution solar imaging. However, I was convinced of the opposite given the number of times the images I take with Baader K line and Hershel are limited by the 150 mm aperture of my Takahashi TOA. The challenge of turning the Celestron 14 was several fold. An aluminium thermal protection was wrapped around the tube to prevent heating and the formation of tube currents. The collimation was checked and tuned the night before for the expected elevation of the sun. Baader Astrosolar d3.8 was chosen in order to get enough light to keep exposure short (<5 ms). A large band red filter, while giving less contrast than narrow band green or blue filters, was used to lower turbulence.
Finally, Autostakkert 2 by Emil Kraaikamp did a beautiful job extracting all the information from the 30s film acquired by Skynyx 2.1M camera at 15 fps.
Now ready and waiting for a large solar spot…
Here is a link to my website :
And another one to my solar page :
We will note many images taken with Baader Hershel prism and K-line filter :