In 2007 a comet passed through our neighborhood and allowed me a chance to try the high dynamic range (HDR) imaging techniques that were being developed at that time. The idea is to combine a range of exposures to get a large range of detail. In this case 10 exposures covering the range from 1 second to 8 minutes are combined, selecting the best tonal information from each. This allows the otherwise obscured ion cloud surrounding the dusty nucleus to become visible as a faint blue-green glow. I was able to use this image as an HDR example in a conference presentation I made on this topic the following week.
On April 8, a friend joined me to observe Hale-Bopp at my
nearby and nearly-dark site at Lake Zumbra.
We enjoyed watching the very young moon set, then went about preparing
to take some pictures. I was hoping to get a shot taken at a smaller lens
aperture so the stars would have less distortion than in my earlier photos.
I thought that the view of comet Hale-Bopp over a cityscape would make a striking photograph. There were only certain view angles and observing times that worked however. To get the comet to hang over downtown Minneapolis in March, the time worked out to be around 3:00 am along a northeast line of sight. Surprisingly few vantage points existed; the streets headed off in the wrong direction, or the view was obscured by trees, buildings or streetlights.
This picture was taken with a Kiev-88, which is a
Russian-made clone of a Hasselblad (a
high quality camera that was taken to
the moon). It uses the larger size 120
format film. A colleague suggested that
this unused camera should be stored in my office instead of his. And since I had no use for it there, I
decided I should try it out on one of my comet photo outings.