Kutter Schief as Solar Scope?

Hi All,

I’m currently using a 90mm F15 refractor + 2X Barlow with a H-alpha filter for solar viewing and would like to get a little more aperture – maybe 5”. Seems like building a tilted component scope such as a Kutter would allow me to get a F30+ focal ratio in a reasonably sized tube without a Barlow. Has anyone tried using a Kutter for this purpose and is there some reason that it wouldn’t work well in this application? Also, is there some coating that could be applied to the mirrors that would perform the same function as the ERF on the refractor? Thanks for any info, Tom

I don't really know the answers you seek, just some random thoughts.

I've made a 4.25" uncoated Newt (primary and secondary) that I used for solar projection. I used a full-aperture "heat window" (similar to an ERF?) that blocked UV and IR. It makes for nice white-light viewing, as would a Kutter config.

As this is for H-a, I assume (I've never used an H-a filter) you would want coated mirrors to gather as much light as possible. I wouldn't trust a thin film on a mirror to block IR and UV rays, people who know better might say otherwise, but I'd go with a full-aperture ERF.

Are you going to buy a full-aperture H-alpha filter to go along with that? Or were you planning on putting it in the optical path at an appropriate point between the secondary mirror and eyepiece? If the latter, is a single ERF going filter out enough hazardous energy in the converging light path hitting the H-a filter (think pinholes)? Would you need a smaller ERF in front of the H-a?

Interesting... best of luck!