I recently built a stepper focuser for lenses which gives me very accurate control over correct focus. By experiment I had also established the focus position variation with lens body temperature for the 300mm lens.. So last night armed with this information collected nine frames while monitoring the lens body temperature and adjusting the focus as needed. It worked extremely well. Bird would be proud as I was inspired by his experiments with mirror temperature monitoring.
Details
Canon 5DH, Canon 300mm F2.8L at F2.8, Hutech LPR filter, 9X8min at an ISO of 200, in camera noise reduction on. Processed with flats in ImagesPlus stacked with Registar and only adjusted levels in PS. Also a bit of R&L 5x5 for ten cycles.
Warning 3.1MB
http://members.optusnet.com.au/~cheekyfish/S&E_85.jpg
It may sound like it is going too far, but look at the results.
Bert