It all looks very promising to me!
I did some experiments last night on a convenient street light and was able to get some further distance between the SA and the DSI3 chip. It is now in the order of 105 - 110mm.
The set up is: DSI3 - SA spacer - 0.6focal reducer - ext tube - SA.
Not sure of the ang/px yet, but it should be about 6-7, as the zero order and then spectra covered 75 - 80% of the long axis.
That'll do for the moment, if only the stupid clouds would go away...
cheers
Mark