What do you think?
The full sized version (all 3.8MB of it) can be seen at 100% by clicking the image.
I've posted some preliminary versions of this image elsewhere but as this is the finished article I decided to promote it into its own thread. The North America nebula, slightly above and to the left of the image center, is fairly obvious by its shape. Immediately to its right is the Pelican Nebula and about two thirds of the way down the right hand edge of the image is the Gamma Cygni Nebula complex around the star Sadr. The brightest star in the field is Deneb in the constellation of Cygnus.
The image was captured with a fairly cheap 165mm f/2.8 Pentax medium format lens but the dedicated CCD camera behind that lens, an FLI ML16803, was far from cheap! The nebulosity in the image is all
from Hydrogen alpha emissions. That is about as far into the red end of the spectrum as the eye can see. That left me with a problem as if I had shown all the Hα as pure deep red I would, IMHO, have ended up with a difficult to see image. Nature comes to the rescue as Hα is usually accompanied by a blueish Hβ line at about one third the intensity so for the image above I added in some blue and then, purely for aesthetic reasons, also added in some green to the fainter and brighter regions (screenshot
) to give a whiter appearance. False colour narrowband images aren't at all uncommon these days so hopefully my choices are acceptable as I'm not representing the nebulosity to be anything other than Hα.
The stars in the image are actually from a totally different set of RGB images captured on the same evening. The Hα image had it's stars removed and the stars from the RGB image were added in. That was done not only to allow some natural star colour to come through but also to avoid the rather selective sampling of stars when imaging in Hα light.
I hope you like the final result but if not then please feel free to offer advice. This is my very first "finished" Hα plus RGB photo and there are so many decisions to be made during processing that I'm sure there's room for improvement.
P.S. Hα was from 5 x 1000 second exposures, each of the RGB images was from 3 x 200 second exposures.