I apologise for the repetition as many would heve seen this image set before but I thought I'd post this collection in this section in case some haven't or it is of interest or better still - of some use as a reference, for those trying to image the Helix for the first time or with new equipment etc..?
This is
a link to a whole album of images of the Helix composed from the same data set. To see the largest image file click on a thumbnail and when an image downloads scroll to the bottom and select "original" from the "other sizes" menu
Equipment and image details:
Telescope: Astrophysics 152mm F7.5 apochromatic refractor (at F8.2 with 4" field flattener)
Mount: Takahashi NJP German Equatorial
Imaging Camera: FLI ProLine 11002M
Filtewheel: FLI CFW-2-7
Filters: Astronomik L & SII Ha OIII narrowband filters
Guide camera: StarlightXpress SXV-H9
Exposure time: L = 1hr, SII = 7hrs, Ha = 10hrs, OIII = 9hrs (Total exposure time = 27hrs)
Data collected over 7 nights: 19, 20, 24, 27, 28, 30 July & 14 August 2009
** Flats taken using AstroHandy Light Ring
** Processed in Astroart4 and Photoshop CS3+
I hope it is of some use to someone
Mike