[Ukastronomer (Jeremy)]

Originally Posted by Merlin66

Tareq,
It's getting more and more difficult to obtain good external etalon (H alpha) filters to use (with a blocking filter) on standard telescopes.

The Daystar Quark seems to be a popular alternative.
The Lunt Cak filter is also available.
https://www.daystarfilters.com/Quark.shtml
https://luntsolarsystems.com/shop/ac...ium-k-modules/

Daystar, Iagree, though I would not personally spend the money on CaK