Since I bought the ???Herschel Prisma??? as Baader names it, one wonders what a ???Prisma??? or prism has to do with solar observing, well as a matter of fact, the Herschel is a peculiar type of prism that reflects about 4.6% of the light you pass through one of the prism faces that is flat to 1/10 of a wave, the rest that is 95.4% of light and heat goes into the prism and exits through the other