After reading an article in the February 2010 issue of the RASC Journal, I decided to re-shoot the double cluster with short exposures, 30 seconds each. I collected about 25 minutes total (RGB 10-10-5) before the target slipped behind the house, and the quality of the subs is variable. This image uses just over half the data, total exposure 15 minutes or 30x 30 second sub-exposures.

Interestingly, almost half the images were discarded because of guiding errors or poor seeing, not that surprising as I was shooting right over edge of the roof from the deck below, and there must be a lot of air disturbance from heat escaping the house. Still, if I was shooting the usual 3 minute subs, I wonder to what extent those disturbances would have disappeared into the exposures as poorer quality overall. Very interesting experiment.