Hello again,
I have completely changed the way I am processing astrophotos. I am no longer utilizing frame calibrations such as dark frame subtraction, flat fields, and bias frame subtraction. The reason? I felt that the images were pretty clean to begin with and that the camera manufacturers and Adobe LightRoom had better RAW image processing algorithms than any independent software manufacturer. I also know Adobe Light Room and Photoshop intimately and I am in control of the entire image processing chain at every step. So my first effort with this new approach is the Horsehead Nebula region in Orion taken at the Winter Star Party in February 2009 (please click on the image for a larger version.} The image is a composite of 5 frames at ISO 800 and 15 frames at ISO 1600 at 7 minutes and 3.5 minutes, respectively. The scope used was a Tom Back 92mm at approximately 400mm focal length and f5. The camera is a modified Canon 450D. I hope you enjoy the image. I will be posting more on my new processing as I work through other images from the trip. Take care and drop me a line.