Narrow band hydrogen alpha filters greatly increase the contrast in emission nebula.  These objects emit H-Alpha light having exactly a wavelength of 656.3 nm (Red light).  I use a 6nm H-a filter, which basically allows wavelengths of 653 to 659 to pass.  Everything else is filtered out, including city light pollution and moonlight.  Most the data for the images on this page were taken when the moon was very bright.  Although the images are simple black and white, I find them pleasing in a more artistic sense.

NGC 7000 & IC 5070

M27 in H-Alpha

M8 Lagoon Nebula

NGC 2359