Natural color composition from the emission of ionized elements, R=80%Hydrogen+20%Sulfur, G=100%Oxygen and B=85%Oxygen+15%Hydrogen to compensate otherwise missing H-beta emission. This composition is very close to a visual spectrum.

Sh2-188, PNG128.0-4.1, in constellation Cassiopeia. An asymmetrical planetary nebula was first photographed in 1965, it thought to be a Supernova remnant due its crescent like shape, now it's known to be a Planetary Nebula. Distance from Oulu, Finland, is ~850 light years. Apparent diameter is ~5 arcmin.

There is not too many images of this Planetary Nebula around. I made a HST-palette composition out of ionized elements, H-a, O-III and S-II, I haven't never seen this one presented like that!
I used a special technique of mine to dig out all the information from the raw data, this is a extremely dim target. I might shoot more lights for this in future.

Technical details:

Processing work flow:
Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack.
Levels, curves and color combine in PS CS3.

Telescope, Meade LX200 GPS 12" @ f5
Camera, QHY9 Guiding, SXV-AO @ 3Hz
Image Scale, 0,75 arcseconds/pixel
Exposures H-alpha 7x1200s, binned 1x1 + 6x1200s, binned 3x3
O-III 3x1200s, binned 3x3
S-II 3x1200s, binned 3x3