Very quick test with Toucam (objective replaced with lens from small hand-held scanner)... same source (20W white bulb on my workbench).
This is the whole image (no cropping).
Next test will be on star (hopefully this weekend).
Resolution could be better, as slit could be closed a bit more (too much backlash in mechanism, I will try to reduce it later)
The double lines in the mid spectrum are Hg lines and 20A apart.
This gives you some idea of the dispersion/ resolution.
Line them up and see what answer the micrometer gives......
Hmmm
According to my reference sheet (http://www.astrosurf.com/buil/us/spe2/hreso14.htm)
the lines are at 5769.60 and 5789.66 A
There should be a nice definate line in the blue at 4358.33 - does that measure up OK?
I tried the numbers you gave me, there is nothing there...
Maybe there is a need for calibration.
Or, there is no mercury in the lamp. Then again.. how come the blue line is there, spot on?
BTW, none of Christian's pages are working for me.
5460.735 is closest to my reading ( 545.6, the brightest one on image).
Actually, I managed to identify and measure all brightest lines here, within +-1.5 nm accuracy: http://astrosurf.com/buil/us/spe2/calib2/osram_1.gif
It was a clear nigh yesterday and I tried it visually on Sirius and Betelgeuse.
I had to remove the cylindrical lens (just one grab screw is holding it in place) to be able to reach focus.
While Sirius spectra appeared to be smooth (no dots), I saw bands in Betelgeuse's.
Next step: a photo of spectrum.
This will be a trickier part because I don't have Toucam modified for long exposures... so I have to do this first (plus an adapter to fit on the eyepiece. The spectra images earlier in the thread were taken from hand, and with plenty of light available for short exposure).
