Rough Science Spectrograph does its thing. Just trying to replicate a simple method described recently by Robin: http://www.threehillsobservatory.co.uk/astro/spectroscopy_11.htm and to verify whether it is indeed possible to record semi-decent spectrograms of bright stars by using my 100mm macro lens and a Baader Blazed Grating mounted infront of it. It does work quite well! Lens was autofocused on a far off light, right through the grating. OK, I tend to be lazy in these matters. Camera was on a fixed tripod, actually a very wobbly one. I used the camera's self timer to calm things down. Top spectrum shows a 2sec exposure at ISO 1600, second shows a 30sec exposure at ISO 100. Note that since I used a fixed tripod, the star trails. By rotating the camera within the lens' tripod collar, and trial and error, it's quite easy to get the trail to go orthogonal to the spectral dispersion. I then sampled a thick slice of the trailed spectrum, collapsed it to 2 pixels high and then expanded it to 100 pixels high to obtain a nice, fairly noise-free spectrogram :-) Looks like a much more effective method than using a tracking mount and multiple exposures, at least for the brightest stars. This height compression/expansion averaging makes it unnecessary to take darks, though in all likelihood one may still have to take flats. To make the colours nicely visible I used Raw conversion as for normal photography (i.e. not Linear conversion). Of course, to make measurements one would repeat the process, but with Linear conversion. Lens was at f2.8 but the Baader Blazed Grating, being in a 1.25" filter ring, effectively stopped it down to about f4. I had used the pop-in LPS filter simply to give me something rather prominent, since this was just a quickie experiment in the street infront of my house. I wanted to be sure that I would see something, even if it's only the absorption bands of the filter :-) The frequent headlights from passing cars were very annoying :-( This set-up gives a dispersion of circa 3 Angstroms per pixel. Nice to note the strong absorption bands of the LPS filter, and indeed Capella's spectrum can be recorded quite nicely by this Rough Science Spectrograph. Next slide shows the full set-up.