Deep Zumbra Sky

Lake Zumbra (Victoria MN), 8:00 pm 30 March 97. Kiev-88 80mm f/2.8, 10 minute exposure on Tech Pan 120 film.

I was finally ready to take on one of my photographic goals: making a color separation style photo using the large image size of the Kiev-88 camera and the fine grain of Tech pan film. I had practiced tracking, I had gauged the exposures, my equipment was assembled and functioning, the comet was at closest approach and the sky was clear!

I set up at my favorite dark sky site and made a practice exposure to make sure the telescope was balanced and the tracking stable. The next thirty minutes were spent positioning filters, making small tracking corrections, scrutinizing the stopwatch, and generally fretting. At the end of each exposure I exchanged filters, advanced the film and prepared for the next shot. At the last exposure I noticed that the filter had fogged over.

Where does dew come from?

Dew is usually considered a hazard of summertime observing, when the nighttime temperatures drop and the humid air condenses on the telescope optics. But I had encountered another condition when it occurs: the sky was so clear that the camera radiated its warmth out to space, actually chilling to a temperature cooler than the air. The springtime air, having spent the day picking up moisture from melting snow, found my camera a cool surface on which to condense , and deposited its moisture on the filters.

I did not get the separation exposures I was after. They turned out underexposed and blurry. My first practice shot on the other hand, taken before the camera had become too cold, showed zillions of stars! The long exposure made for a "deep" image of the sky with stars showing through the veil of the comet's tails. The ion tail shows an interesting structure that reveals its turbulent flow in the solar wind.

Temporal elements

An airplane crossed the camera's field of view during the exposure, writing its blinking trajectory across the film. In a way, the plane is much like the comet, a brief unusual source of light moving across the sky, captured only because the shutter of a camera was open for a few minutes at the right time and place.

Thor Olson