Pixel relative response of a modified Canon EOS 350D (click here for details). The dashed vertical lines indicate the position of major nebular spectral lines. From left to right: Hbeta, OIII doublet, Halpha, SII doublet.
 

Measured relative transmission of filters used. Click here for complementary informations.
  
 

Configuration #1
William Optics ZenithStar 80 refractor + modified EOS 350D +
Astronomik UHC filter + Astronomik IR block filter.
Stack of 6 exposures of 240 seconds each.
Processing Iris: standard pipeline + boost of G layer by a factor 1.2
and B layer by a factor 1.6 
 

Configuration #2
William Optics ZenithStar 80 refractor + modified EOS 350D
R band: Astronomik SII and 350D red pixels,
G band: Astronomik UHC + IR cut and 350D red pixels,
B band: Astronomik UHC + IR cut and mean of 350D bleue and green pixels.
Stack of 6 x 240 seconds for UHC - Stack of 9 x 240 seconds for SII. The R layer (SII) is boosted by a factor 3.

Configuration #1: combination of added filter transmission and 350D pixel responsivity.

Configuration #2: combination of added filter transmission and 350D pixel responsivity.
 

Typical relative intensity between emission lines of the gaseous nebula , here a region of Messier 8 - Spectrum acquired during the September 2002 mission at the 60-cm telescope of Pic du Midi Observatory. Note the Halpha/Hbeta ratio, measured near 4, a classical value (this ratio is also a tracer of interstellar extinction). The left spectrum profile shows the red and near IR regions of M8.