After reading Uwe Zurmühl article "Objective Gratings for Amateurs" in Spektrum 55, I decided to try an objective grating and stopped spending my time on a slitless spectroscope.
While the Star Analyzer 100 is readily available, it is small and would only be useful on the brightest stars. I decided to try the 45mm format grating from Paton Hawksley. I chose the 100 lines/mm grating to give me a wide field of view.
I built a slide holder and connected it to the front of my 72mm f/6 refractor. According to TransSpec V3.2, by Ken Harrison, I should get a resolution of R = 2000. This is ten times greater than my converging beam setup using the Star Analyzer 100.
I was very pleased with the results. I used Menkalinam, an A2V star, for focus and calibration. With all of the discussion of Betelguese, I wanted to take a spectra of it. I took thirty 40 second exposures (along with dark frames) using an ASI 174mm camera. I stacked the frames using Astro Art.
The attached picture shows my Betelguese spectra. This is far better than any spectra I ever took with my converging beam setup.
I made some inquires with several manufacturers about getting a larger 100 lines/mm grating (i.e., 75mm square). Sadly, the costs went from $500 to over $1000!
Edited by cardanoc, 14 January 2020 - 04:41 PM.