I recently posted this shot on a couple sites and was promptly asked the questions; how’d ya do it? So I wrote up a how-to and posted it in a couple of the forums where it was posted. I’ve added it to my flickr photo page and now cross posting it here for archival purposes.
I took this star trail shot from Stanley lake. A high layer of clouds that was moving in so the stars (planets) near the horizon had a halo effect and turned out quite large. but it added some color. this is a stack of around 80, 30 second photos at 200 iso and around f4.
Setting the scene: I was sitting on ice covered rocks on the side of a half frozen lake with wind blowing across it at me, it being 5 degrees, watching my camera blink off and back on every thirty seconds for two hours…….
A lot of planning went into the shot… I’ve been scouting a location for this image for a month or two now. I knew what I wanted and how to do what I wanted but needed perfect time, weather, and location. This lake is three hours from nowhere, in central Idaho. Being 10-15 miles from the nearest person in 5 degree weather helps with the whole clear sky bit. I had four nights staying in the area to pull it off but weather on three of them was foggy and snowing, not conducive to star photography. On the last night I had available we had a break in the weather and I made the trip from town out to the lake. My wife wasn’t feeling well so I made the trip alone. I knew where the sunset would hit and roughly how the stars would rotate into the sunset so I placed the peak on the opposite side of the image. Like I said, for the past couple of months I’ve visited countless lakes in Idaho looking for a spot that had a perfect setup for the image floating in my head.
I got to the location right at sunset and by half hour past I had my camera setup. I use a homemade remote trigger. I shot several test shots to get the comp I wanted and to set the focus, once I had that, I locked everything down. At this point the sun was well past set but still had a nice twilight going with just a slight warm color to it. I shot a foreground exposure around two minutes 200iso and f4. then I waited about half an hour or so before starting the trail shots.
For the start trails I played around for a few exposures but found that 30 seconds, 200iso and f4 was about where I wanted it. I did have a high thin cloud layer moving in from the southwest so the planets (Venus and Jupiter) had a touch of halo around them. I thought it might ruin my shot but it seems to have worked anyway, they just look larger. I did have to use a slightly darker exposure so they wouldn’t totally wash out.
Once I was happy with the exposure I set the camera to auto drive and locked the shutter switch on my remote. The camera took around 80 consecutive shots, each 30 seconds. I used about 70 of them, throwing out the first few and the last couple. The light had stayed too bright longer than I expected so I didn’t get as long of a shoot as I wanted. Had I planned the start time better I could have stayed later but my wife was expecting me back, we were celebrating our anniversary and the only restaurant in town (that’s open during the winter) didn’t stay open very late.
I ended up with a fairly bright foreground exposure, a not so bright twilight exposure (just in case I needed a halfway shot to blend the other two) and 80 star shots. I use a image stacking action in CS3 to stack the 80 images. Blending the shots via lighten. The result had just the star trails, the reflection of the planets and to my surprise an area of red sky, not overly bright, but it was there.
I blended in the the foreground exposure bringing in the mountains and mountain reflection and most of the brightness and blue color in the sky. I duplicated the star trail photo and masked off everything but the red area caused by the clouds moving in through the shot. I blended in this second layer at low opacity via overlay to really bring out the color that was already there. I used the intermediate image I shot (the halfway/twilight exposure) at a very low opacity to blend the two exposures together. I could have gotten away from this via a little burn/dodge, but I wanted to stay away from that.
I didn’t do any noise reduction, and as shown here, no sharpening. My cleaned up version I’m working on for prints, I sharpened the edge of the mountain, and took out the limb in the bottom right corner. I also cleaned up some areas I missed where stars from the foreground exposure were in the original blend.