This is a single 142 seconds exposure with an unmodified Nikon d3100 DSLR camera at ISO400. It has been taken under light pollution WITHOUT any LPS filter. Note the wonderful star colors in the field.
Telescope: 385mm (f/3.65)
Guider: SBIG ST7XME on a 355mm (f/6) scope.
Software: Aperture v3.1.2 (Mac). Only histogram adaptions has been one in the NEF (raw) file. Image: Messier 39 in Cygnus