A RAINBOW OPTICS Visual / Photo / CCD Star Spectroscope consists of two components, a grating cell and a lens cell, which attach to your 1.25" eyepiece. Both components are made of black-anodized aluminum.
The grating cell, which screws into the bottom of your eyepiece, contains a glass, blazed, diffraction grating. Its delicate grating surface is protected by a second glass disk. The blazed grating directs most of the light into one of the first-order spectra, resulting in a bright spectrum. This grating's performance is superior to that of a non-blazed grating. And unlike a prism, which distorts a spectrum by spreading out blue light more than red, this grating creates an undistorted, constant dispersion across the entire visible spectrum.
The lens cell, containing a spectrum-widening cylindrical lens, is secured to the top of your eyepiece by nylon thumbscrews.
There are some important advantages to this new spectroscope design. It is reasonably priced, easy to use, compact and lightweight. Another advantage is the innovative method of adjusting the length and width of a star's spectrum. Complete instructions concerning these adjustments are contained in the owner's manual.
This spectroscope is very versatile and is compatible
with a variety of telescope types and setup configurations. Each telescope has
its own ideal setup. For example, a favorite setup for examining the spectra of
stars with an 8-inch f/10 Schmidt-Cassegrain is to use a 26mm Plossl
eyepiece and then screw the grating cell into the telescope end of the star
diagonal. With this setup, Sirius' spectrum is breathtakingly beautiful and
Betelgeuse's spectrum reveals a wealth of detail in its banded structure.