The link in the earlier post takes you to M. Gavin's page. I'm using his WPO design which is a very basic spectroscope. It uses a reflection grating (30mm sq, 600/1200 lines/mm), a standard tele lens ( I use a 135mm f2.8) and a small mirror to "pick-off" light from the telescope. I'm using a ToUcam as a camera ( hopefully to upgrade SOOOON to a MX7c)
In the telescope adaptor I have a narrow slit at the focus of the telescope and also at the focus of the tele lens this gives a "cleaner" spectra.
Depending on the grating and lens you get differing resolutions which allows more detail to be seen in the spectra.
I use IRIS to manipulate the raw image and spectraview to prepare a 2D graph which allows better analysis.
With a 10" telescope should be able to get usable spectra of 9 mag stars etc etc.
I'll post a photo of my set-up at the weekend.
The attached photos show the set up. The connector to the telescope with the same pick off mirror, the 135 telelens and the grating which I mounted in a plastic project box. The grating box connects to the lens by using step-up filter rings.
