If the mount is not tracking, quickly centre the image just before 3rd contact. Don\'t forget to put your filter back on after the 3rd contact diamond ring and Bailey\'s beads, then finish taking the partial phases.
The key to successful eclipse photography is careful planning and good technique. In order to decide what events you want to capture, and what exposure times you should use, consult current eclipse reference books and webpages. Before the eclipse, practice on the Moon or the filtered (or projected) Sun, with your particular equipment and the film that you have chosen. You can\'t test all of the exposures but you will become familiar with your setup. Finally use a prepared shooting script which includes accurate event times for your viewing location, shutter speeds and when solar filters should be on or off. If possible have someone calling out the event times for you, but if you don\'t have that luxury, you can prepare an audio tape timed to give you the warnings.
Good luck and clear skies!
Corona photos taken with SK 705AZ3, other Solar Eclipse photos taken with SK 1025AZ3, both by Francisco A. Rodríguez Ramirez, Spain.