Sunday, 17 May 2015
We spent a long weekend in Milow, less than one hundred kilometers west of Berlin. This is one of the "darkest" areas in Germany. So much indeed, that there is a Star Park, i.e. a place to look at the stars at night. There were no clouds on Saturday night and with the new moon being tomorrow, the conditions were close to perfect. Therefore I decided to give star photography a go, something I had been wanting to do for a while.
Unfortunately, as it gets dark really late, the children were already in bed and could not share the experience. From the technical point of view, I had in mind to tether the camera to the tablet, set it in bulb mode and let it capture a long exposure and come back later to check the result. As it happened, I had forgotten the usb cable at home and I had to figure out a plan B. Plan B in this case meant manually taking a series of 30-second photos over half an hour and hoping that I would be able to stack them together later at home, which was easier than I thought.
The result shown above is made of 23 photos taken over 27 minutes (the processing of each 30 second shot takes a while with my old camera!). The settings were 30 seconds at 3.5 aperture, ISO 1600 and focus set to infinity, I very rarely use ISO above 400 on my old camera, as noise levels are very high, but there was no much point in doing all this just to get a couple of stars. In order to avoid getting bored in between clicks, I had a Click podcast on my mobile. It´s not a coincidence that by the time I was finished with the podcast I decided enough was enough and called it a night. I had no idea how much the stars had rotated, and, for that matter, I was not even sure in which direction they were rotating.
In order to stack them together I have written a short script that goes through each pixel in each photo and takes the brightest one in the stack for the final shot. Not particularly sophisticated, but it seems to do the job. In case somebody is interested, this is the code for a simple star stacking program. And if somebody can pointo to better ways of doing this, please leave a comment.
All in all, I would say that the biggest challenge was finding Polaris in the sky, an ability that probably not many children have these days in big light-polluted cities. When was the last time that you saw the Milky Way?