Rainbow Optics offers 2 spectroscopes: a two-piece Visual / Photo / CCD model and a one-piece Visual model.

Star Spectroscope: Visual / Photo / CCD, $249

A description of the two-piece spectroscope can be found on the Design Page.

The two-piece Visual / Photo / CCD Star Spectroscope

Accessory for the Visual / Photo / CCD Star Spectroscope

1.25-inch Threaded Star Diagonal, $49
Page 7 of the spectroscope Owner's Manual describes an optional technique of screwing the grating cell into the star diagonal of a f/10 Schmidt-Cassegrain. This will give a nicely proportioned spectrum when used with an eyepiece of about 26mm focal length. This setup is also useful with slow focal-ratio refractors. But if your brand of star diagonal is not threaded for 1.25-inch filters, you can use this star diagonal. Or if your f/10 Schmidt-Cassegrain is equipped with a 2-inch star diagonal that has a 2-inch to 1.25-inch reducer, you can rotate the 2-inch diagonal 90 degrees and then plug this 1.25-inch diagonal into the reducer.

Star Spectroscope: Visual, $199

This instrument is for visual spectroscopy with 1.25-inch and .96-inch eyepieces. It fits eyepieces with an eye-end diameter of 1.5-inch or less. This is typical of most Plossls, Kellners, and orthoscopics. This spectroscope looks just like the lens cell of the two-piece spectroscope described in the Design page but it contains both optical elements: a spectrum-widening lens and a high-performance, glass, blazed diffraction grating. The grating is different than the one used in the grating cell of the two-piece spectroscope because it is positioned on top of the eyepiece instead of below. Spectrum length is fixed and spectrum width is adjustable. This spectroscope is a bit easier to set up than the two-piece model.

The one-piece Visual Star Spectroscope