In photography, there is a way of making time visible – through long-time exposure. Either it can the silky looking water cascading over the rocks, the streaky looking clouds passing by, or,what I like most, the stars that show their path while the earth is moving around it´s axis. Mainly, there are two different approaches of making startrails…
1. Multiple exposures:
In this recent image I´ve made 240 single images, each 30 sec., and stacked them with software like http://markus-enzweiler.de/software/software.html , with minor adjustments in Lightroom 3. I started the exposures at 11:15 pm, at the beginning of the astronomical twilight, when the sun is about more than 12 degrees below the horizon, and still got a look if it were taken right after sunset. The “coming-through” clouds also add something special to the scene, though sometimes the trails look a bit like “interrupted”. Also noticeable are the different colors of the stars, which only works on a moonless night.
2. Single exposure:
This is a 40 min. single exposure from the same night like above, intersected by an Iridium Flare at the lower left edge, between the first and second tree. With this method, you have to determine the proper settings, and some trial and error will be needed to get some results. And just keep in mind that the “in-camera-developing” of the image takes about the same amount of time than the “taking”. I always put the in-camera noise reduction on and haven´t had any problems with noise so far.
Either way, there opens up another possibility by having done it multiple or single: stacking the trail image with a “static” star image, which is taken a few minutes before/middle/after you start the main sequence – in this case before…
In the upper right corner are the bright tracks of Alkaid, Mizar and Alioth visible, which belong to the Big Dipper, while the bright lane to the left is Arcturus, the brightest star of the constellation of Boötes.
Give it a try the next time you are out and don´t be afraid of the dark. Enjoy!