Issues and tips in long exposure photography

This week I had a lecture at Downstairs photo club here in Copenhagen. In front of about 30 people, I shown my work and I presented my ideas about long exposure technique and black and white photography. One of the parts that people seemed to be very interested about was the slide containing the tips for long exposure. All the issues that I am presenting here are real, and I was facing them during almost 2 years of using this technique; the solutions are the ones that I am currently using in order to avoid those problems. • focus is impossible with extreme ND filters on the lens. This one is rather obvious: when you place a 10 stops ND filter on the lens, the amount of light that is hitting the sensor is about 1000 times less than without the filter; this light is not enough for getting proper focus, neither automatic, nor manually. Focus, lock the focus, place the filters, shoot – this is the correct sequence that always works. For locking the focus, I half press the shooter...