This is a stacked composite of 27 exposures, each capture shot at 4 minutes, f/2.8, and ISO 400. I used my 10.5mm digital fisheye, and as you can see the image is pretty much pointed north up Owens Valley from our location in the Alabama Hills. Total exposure time was about 108 minutes, or one hour and 48 minutes.
To process the images, I opened them all using Adobe Camera RAW, and synchronized the settings. There were a few frames that needed work to take out elements that would have distracted—such as airplane trails and traces of a green laser pointer on one of the rocks. In Photoshop, I painted these out crudely using a black brush—knowing that the stacking process would insure that my “retouching” didn’t show, since only the brightest pixels would be picked.
Next, I saved all the images as PSD files and closed them. I used the Statistics action—available in the Extended version of Photoshop—to stack the images, with the Mode set to Maximum (as I mentioned, the point of this was to make the combination using the brightest pixels).
I used a lighter version of the final frame—there had been some light painting on the rocks—to brighten the foreground. It was easy to add this to the composite with a layer, layer mask and gradient.
The formation to the right of the image is called “The Three Nuns.” While we were all exposing we had a nice little midnight party, located constellations and with hot chocolate and marshmallows for those who wanted them.
Here are some more recent star trail photos: