One thing I love about photography is that sometimes, it allows me to see beyond a moment in time. Done right, it can combine these singular moments into one linear narrative.
I started star trail photography at a whim. I was in the mountains of Puerto Rico one night and the sky was clear. Not too much light pollution (Bortle 4/5). Full moon does not rise until past midnight. Conditions were near perfect, so I got on with it.
The Gear:
My set up includes:
Canon F-1 (my little soldier);
Canon FD 20mm lens;
Shutter release cable;
Kodak Portra 400;
A tripod.
Things to Note:
A couple things I did consider before the shots:
The 500 rule for full frame/35mm cameras: the formula for photographing stars is 500/(focal length of your lens), before you start seeing visible trails in your image. This meant I would have to wait at least 25 seconds with my lens. But this wide angle lens is quite perfect because it would capture a lot of stars in its frame, not to mention it is a very fast lens (wide open at f/2.8);
Choice of film: I actually brought some Ektar 100 and Tmax P3200 for the purpose of night sky photography. Ektar is low ISO, meaning it would not succumb easily to reciprocity failure (when film starts losing sensitivity after a long exposure), which makes it an excellent candidate for long exposure photography. Tmax P3200, on the other hand, is very sensitive to light initially, but cannot pick up on more signals after a couple minutes, which makes it preferable when I want to see the sharp stars of the Milky Way. Unfortunately, I did not time my shots right, and I ended up with Portra 400 still in the camera on this night, so I decided to just give it a chance;
I was on the fence about light from the moon leaking into, and hence destroying the star trail photos. More on this later.
I left the camera out for about two hours for each photo.
The results were stunning.
Conclusions:
I had some interesting observations:
Portra 400 held up very well. I edited the photos to increase saturation because the originals looked a bit flat, but no visible effects of reciprocity failure. The details are very much there: it is very easy to even tell the stars by the color of their trails (red Betelgeuse vs blue Rigel);
There is a considerable amount of vignetting as a result of using the 20mm FD lens, which I was completely fine with;
A full moon actually made the shots towards the end. It lit up the sky and the surrounding trees with just the right amount of brightness, creating a cool effect as if the stars were shot in broad daylight.
Changing It Up:
The second time I attempted star trails was in Maine, the night before the eclipse. I had loaded Ektachrome E100, a low ISO slide film, in hopes for some bright colors and better results. For this experiment, I kept all the rest of the setup the same. Or so I thought.
Intense color shifts. The positive image very much tending to blue/green, making it rather eerie to look at. I had to edit it to B&W for a more reasonable effect.
I thought about possible reasons. I ruled out lab error because the other photos came out just fine (including the eclipse ones!), and was left with two conjectures:
Ektachrome does have a tendency to have color shifts when overexposed, specifically to the blue/green end of the spectrum, so this might have been in the cards all along;
Temperature could have played a part. In Puerto Rico, it does not get colder than 60°F at night, whereas it was probably in the low 30s in New England. Film is made of chemicals, and would most likely react to temperature changes, especially if it were left out in the cold for over two hours.
However, I will praise Ektachrome for its details and consistency. The B&W version looks great in my opinion.
Exercise for Readers:
Now, the hard part: can you identify stars/constellations based on these images? :D