If you have never had the good fortune to view the sun in hydrogen alpha through one of these filters, allow me to explain.
Lumicon specs this H-alpha filter at +/- 0.75 Angstroms on the H-alpha line of 656.28 nanometers, i.e. 1.5 Angstroms passband. (Coronado Solarmax filters have a typical passband of 0.7 or 0.8 Angs.) I had the opportunity to do a comparison with the Thousands Oaks H-alpha, the Lumicon showed many more faint prominences and much more detail. While Lumicon never sold this filter with the intent of viewing solar disk details, they are visible, although very faint; I used a C-11 and a 56mm Plossl.
That said, this filter is specifically designed for viewing solar prominences on the limb, and it does do that extremely well. Included are some pictures that I took using this filter, please keep in mind that these were taken with a Kodak digital camera through a 13 mm eyepiece and I'm no astrophotographer.
The filter consists of two major components: a 77mm pre-filter that is placed in front of the objective and a 22mm blocking filter placed before the eyepiece. The blocking filter housing also contains an infrared filter and tilting mechanism to adjust for Doppler affects and fine tuning the passband. The housing fits into a 2" diag and has 1-1/4" barrel for eyepieces and is T-threaded for attaching a camera. The filter needs to be used with at least a 1500mm focal length scope. I have used it with my C-11 and TV-85 plus 2.5x or 4x barrlows. The only thing you will need to provide is a mask to hold the 77mm pre-filter in front of your objective lens. This can simply be a lens/dust cap with a 77mm diameter hole cut in it. (The mask shown in the photo is for my C-11 and is not included.)
Lumicon H-Alpha Prominence Filter - $625
Money orders are OK, however I prefer PayPal. I will pay for insurance and FedEx 2nd business day delivery. If you have any questions feel free to call or e-mail.
Thanks for looking,