Click image to enlarge
Splitting two very closely spaced emission lines:
[NII] @ 658.4 nm
Ha @ 656.4 nm
Taken on Noevmber 24, 2006 from my backyard in Castro Valley, Ca
To
see this image in [NII], Halpha and [OIII] click here 
Stinger 450 Classical Cassegrain (18" f/12.6)
Lumicon Giant Easy Guider with Focal reducer for final: F= 3366mm, f/7.1
Finger Lakes CM10 MaxCam imaging camera operated at -20C
Robofocus
Finger Lakes CFW1 Filter wheel
SBIG ST7E guide camera
Custom Scientific 3nm FWHM Ha filter (50mm diameter)
Custom Scientific 3nm FWHM [NII] filter (50mm diameter)
Three exposures of 20 minutes through Halpha (2x2 binned)
Three exposures of 20 minutes through [NII] (2x2 binned)
Two hours total exposure time