This picture of M51 was shot in San Bruno, CA, near the airport.
Telescope: Celestron 9.25″ SCT with Celestron f.d 6.3 corrector / reducer
Camera: QHY8 CCD cooled down at approximatively -40C
Filter: Astronomik CCD CLD
Composite of 6 images of 360sec and 17 images of 240sec.
Software: Photoshop CS4 and NeatImage. I applied high pass filters to enhance contrast in the Galaxy spirals and use Astroart deconvolution to enhance details.
My new camera QHY8 is really amazing – small in size, very easy to use, with a large CCD sensor, and so few noise that I don’t need to shoot each time dark frame. In fact the noise is so low I barely notice the difference when calibrating with Dark frames.
I am always in the quest of improving my deep sky imaging and battling with light pollution. Many nights, the best magnitude I can visually see is between 3 and 4… The skyglow of the city, San Franciso airport, and close caltrain station surround me… I tried different ways to improve contrast by using different light pollution filters and narrow band filters..
I am impressed with the performance of the Astronomik CLS CCD filter. It really reduces the light pollution, filtering the city lights, but let critical wavelengths such as OIII passing through. I was able to compare with other filters such as the Orion Skyglow photographic filter, and even through the Orion filter allowed me to take nice pictures (see the Pacman nebula with an Orion 102ED, Orion Skyglow filter, and Star Shoot Pro II), the Astronomik filter blocks light pollution to a greater extent and allowed me to do exposures of +6 minutes even with short focal ratio (f/d 4), and this without saturating the image.
Astrophotography in Urban Environment 
