Comet 17/P Holmes
November 4, 2007, 10:30pm PST
Victoria, BC, Canada
The gas cloud surrounding the comet continues to grow in size. I am now using a 400mm telephoto lens instead of my 2,000mm f/10 telescope in order to fit it in the field of view. The green glow around the comet, has now sprouted an ion tail (4 o'clock position) and a dust tail (1 o'clock position).
Using my unmodified Canon 30D and a 400mm telephoto lens mounted on an Astrotrac equatorial mount, I acquired 60 images and stacked them to produce this resultant image. Due to the larger size of the comet and lower overall surface brightness, I increased my exposure time to 30 seconds for these images. Please note: the image size is much larger as used for my previous three images due to the increase in the comet's overall size, therefore size comparisons cannot be made using the images as posted.
Optics: Unmodified Canon 30D and Canon 400mm L series telephoto operating at f/5.6 mounted on an Astrotrac equatorial mount.
Exposures: 60 images at 30 sec
Custom white balance to compensate for IDAS LPS filter
ImagesPlus 3 beta 10: digital development of Canon Raw to FITS, dark & flat frames applied. Averaging used for stacking the images, then aggressive Digital Development applied to the resultant image, and conversion of this image to 48 bit TIFF for further processing.
Corel PhotoPaint X3: convert to 24 bit RGB, contrast stretch background to enhance the tails, image crop
ACDSee Pro 2: hand spotting image, conversion to jpg.