Conditions: aquired from various dark sky locations in New Mexico and Denmark, 2003-2005.
Setup: Nikon 180 mm ED lens at F4; DF-2 focusser; H-alpha, SII, OIII narrowband + red, green continuum filters; ST10XE, Takahashi EM-10 mount (click here for a description of this setup)
Exposure: 1x2 mosaic with a total of 23 hours exposure time; 61 narrowband frames (1200 sec), 24 continuum frames (360 sec), all with 1x1 binning
Processing (Mira, MaximDL, Registar, AIP4WIN, Mathematica, Photoshop): dark+flat callibration, de-bloomed, registered, median/avr combined, color balanced, continuum subtracted, digital development, combined as RGB(Ha-SII-OIII), tweaked curves/levels/hue, cropped and reduced 50% for web format (full resolution version available here)
Since the Veil Nebula resides in Cygnus the view is so cluttered with stars that deep exposures fail to convey the true beauty of this object. I therefore used narrowband H-alpha, SII and OIII filters to maximize the nebulosity relative to the star field. However, when trying to reveal the weakest nebula regions the resulting image still becomes quite cluttered with stars. To supress the star field even further I made exposures through continuum filters so that the stellar continuum present in the narrowband images could be subtracted. The process of continuum subtraction is simple in principle, but can be more complicated in practice (here's an outline of the process I developed). In the final image the stellar flux has been reduced to ~25% of that in the narrowband images and just 1% of that present if ordinary broadband filters had been used, thereby letting the Viel shine brightly in its own light.
Here's my main page where you can see more of the pictures I have taken so far.
Comments greatly appreciated! (mikael@leif.org)