Will it work?

[Merlin]

Consider this fellow Sol-worshippers. If I substituted a KG3/5 filter for the ND 3 in my APM Herschel prism and added a variable polariser, would it be save to use in this mode with regard to IR and UV?

The KG filters have a green tinge, which is better for contrast than a ND 3. I could also add the BAADER Solar Continuum filter to the optical train.

[michael.h.f.wilkinson]

I use the ND3 and Baader Solar continuum for best results. I would be very wary of using any filters not designed for solar work.

[Merlin]

You might not be aware that the KG filters are heat rejection filters. They can substitute for wornout mini-ERFs in PSTs and ERFs in other solar 'scopes.

What concerns me most here is whether the ordinary KGs ( without special coatings ) block the UV.

The best views I had of sunspots and granulation were through a modest 60mm/f.11 PRINZ refractor.

I fixed two 58mm diameter Cokin polaroid filters over the objective, ensuring that one filter could be rotated in relation to the other. At the focuser end, I had a small Herschel prism with a mid-green filter fitted at the bottom of the eyepiece tube.

What I didn't know at the time was that polaroid doesn't block the IR. When I discovered this, I added a ND filter, but the clarity wasn't as good as with the previous arrangement.