Lumicon Solar Prominence Filter, 1.5 Angstrom with Energy Rejection Prefilter
The cost-effective Lumicon Solar Prominence Filter System consists of 2 pieces. The first is the Lumicon S.P.F. 77mm Prefilter that blocks all light above red (infra-red, heat) and all light below red (incl.UV A&B). The Lumicon Prefilter is normally bonded to an optional off-axis mask for your telescope, or, if you prefer, to your own homemade mask mounted securely over the front aperture of your telescope. What I have done with all my scopes is cut a 77mm hole in the cover and mount a 82mm to 77mm stepdown adapter with cover from Adorama for $10.
With the Prefilter now mounted over the front of your scope in its mask or holder, only cool, safe red light enters your telescope. The second piece of the Lumicon Solar Prominence Filter System is the narrow-bandpass filter in the main body. This mounts onto the focuser or eyepiece end of your telescope. The Lumicon 1.5 Angstrom bandpass Solar Prominence Filter element is mounted on a tiltable plate in the filter body to allow "tuning" of the filter element in relation to the incoming cool red light, picking out an even smaller 1.5 Ang. sliver of the cool red light centered on the 656.3nm H-alpha line. The contrast gain is such that the sun's prominences become easily visible jutting of the edge of the sun. Brighter filaments and sunspots can also be seen on the surface of the sun. Best used with an f-ratio of f/20 or slower (40 or 50 is best, but even up to f/60) for best contrast. The Lumicon Solar Prominence Filter has a 2" barrel for 2" focusers and can be adapted for 1.25".