For Corona Galore, I was using two cameras during the eclipse. To capture the delicate detail in the outer corona, I used a 400mm lens, one second shutter speed at F-8 on ASA 25 negative film. This long exposure "burned" out the inner reaches of the corona but that's why I had to use at least two cameras. In fact, I had four cameras (one video) going for the entire event. The video footage resulted in a "Keystone Astronomers At Large" episode "Totally At Large in La Paz, July 11, 1991." .