The Sun is particularly active this week, with one huge sunspot ostensibly visible to the unaided (filtered!) eye; my eyes are not that good but I decided to try out my 300 mm lens on the Sun since I didn't feel like setting up a telescope to shoot through.  Just in case anyone has the impression that I think these pictures are any good, let me assure you I don't :)) Some fantastic ones are here and here.  How do they do that?