Quote:
Originally Posted by Merlin66
Al,
On the Rigel graph/ curve, all the "data" below 400nm is suspect... I would dump it and ignore, I lay a bet it's not real. The atmosphere cuts out most of everything below 350nm and there's effectively zero response from the DMK at 300nm.......
Robin's note is great. VSpec, Tutorial 5, ( http://astrosurf.com/Vdesnoux/tutorial5.html)
gives the VSpec method in detail ( just remember, see page 7, to "Edit-Replace")
re Camera response: I occasionally use the Canon 350D with Canon and Zuiko lenses with the Baader grating mounted infront of the lens.
I find the response curve can change dramatically depending on the lenses being used!!
Terry, A little surprised to get best spectra focus when the zero order is focussed... I usually have to tweek the focus to get best results ( 12" LX200, 200mm Littrow, 1200lpm grating). The reducer also reduces the scale of the spectra ( ie shorter focal length). The distance from the grating to the CCD chip I find is more imprortant for dispersion and resolution.
Great stuff... we seem to be generating some interest looking at the number of hits on the thread!!! |
OK Ken. So you're saying the drop off of the spectra below 400nm is to be expected, so I shouldn't be expecting to capture a spectrum similar to the library spectrum in this range... so I probably shouldn't be so concerned about my apparent lack of blue response.
I must say I'm loving this thread! I'm learning heaps! Thanks guys!
Al.