It wasn't until late on the sunday afternoon when I managed to get a very brief shot of our star using the DS CaK filter on the 40mm at f20, the sun was only about 10 degrees above the horizon, given that there was passing high cloud the outcome isn't too bad. I did a bit of experimenting with the double stack CaK unit; angling one of the CaK notch filters with respect to the other with a view to throwing the reflection doesn't work. This creates an offband image lacking in finer detail. By far the best result is with the filters parallel faced, this produces the most detail however with a slight haziness as a result of an overlapping reflection / ghost. I think I may have to look at placing a suitable blue filter between the 2 cak units as a possible solution to this ghost image - another experiment to try, shame it is heading towards winter which hinders progress! Still, very promising results!
