These comets were difficult to photograph because they were low on the horizon where twilight, light pollution and aerosols made it difficult to achieve an adequate SNR.
The Comet Panstarrs images were made using a Canon EOS50D at ISO 3200 with a 100 mm f/2 lens, and the Comet Lemmon photograph was obtained using a Televue 85 mm refractor at f/5.6 using the same camera. All three images were made from stacks of a dozen or more short exposures. The images were stretched to the noise limit to help reveal the fainter parts of the tails.
Higher resolution versions:
http://www.flickr.com/photos/mlparkinson/8544160034/
Gee Panstarrs is low now.
