Direct Vision Prism

[morls]

HI,
I've been reading Hurtung's, and he mentions using a direct vision prism to study the spectra of objects in the eyepiece. I'm just wondering if anyone has experience with this?
Cheers
Stephen

[Merlin66]

Stephen,
Yes. Many years ago I read the same and used a small 60 deg prism visually to help distinguish planetary nebulae etc.
I even built the prism into a 35mm cassette to make it easier to hold at the eyepiece.
Certainly does work!!!

[morls]

That's a great idea!

[Wavytone]

Stephen the other gadget you will find *amazing* is an OIII filter, these screw into the eyepiece barrel. Try it on any planetary nebula. Eta Carina for starters.

Good ones are expensive so try someone else’s at a society observing night, star party or similar before deciding to part with cash.

With these, there is a “band pass” which is the range of wavelengths they transmit. The narrower this is, the more it suppresses the sky background, stars and everything else, yet the nebula stands out.