Joanne and I go to Hawaii a lot. When people hear that they assume I know what to do there as a tourist - in reality, we spend a lot of time with family and relatively little time doing other stuff. In fact until a few years ago I had never been off Oahu. This time we went to the Big Island for a few days. Since it wasn't very long we decided to stay based in Hilo and explore the east and north sides of the island, thereby missing all of the good snorkeling in Kona. Hopefully in so doing we also avoided Dengue fever, although we're still within the incubation period.
Capturing stars above the lava lake in Kilauea caldera was the main photographic challenge. The conditions were difficult - high winds, frequent rain showers (i.e., every few minutes), and only brief (5 minute) gaps in the clouds to reveal any stars. This is the challenge of being a vacationer as opposed to somebody who lives there and can simply choose a relatively clear night. Once we encountered the right gaps, then the actual imaging challenge was to expose for sky and crater at the same time. The solution ended up being the "black card" technique, which simulates a gradient neutral density filter. You cover up the bright part of the image (bottom) with a dark object (black card preferred, but what we had was the national park map with the black band on top). Start the long exposure and when the time is right, gradually pull the card down to expose the bright part. How long you keep the bright part covered is a function of how much brighter it is than the surroundings. For example, if it's 2-stops too bright (4-fold brighter) then you only expose it for the last 25% of the exposure. In a civilized world one would probably have a stopwatch... I just counted in my head and pulled the card down when I felt like the time was right.
