|Back Porch Milkyway, Chesterfield New Hampshire|
In the last several weeks I have been exploring star field and star trail photography. It have dabbled in these areas in the past including taking long star exposures on film years ago, but recently my interest has been renewed by a new project. Over the last year or so I have had the wonderful opportunity to work with Rabbit Ear Films, a small local group of dedicated, talented people, on a documentary film about Mount Monadnock. I am a rank amateur at video but have taken the opportunity to learn while contributing in small ways to this exciting project. Our goal is to produce a feature length documentary, meeting the high broadcast standards of PBS. Leading our group is Steve Hooper a veteran editorial photographer for the Keene Sentinel and Dan White who works with Florentine Film, Ken Burn's production company. My role has largely been to collect high resolution "B Roll" video of views around the mountain. This works well for me since it is largely video versions of the still images that have been a major part of my portfolio. It is the kind of work that the 5D Mark II handles especially well.
Recently I began thinking about using time-lapse techniques to record star fields moving across the iconic profile of Mount Monadnock. I thought it would make a nice addition to the film. I have experimented at home using an intervalometer and my old Canon 5D. I decided to dedicate my 5D for time-lapse to spare the shutter on my newer Mark II. Recently Steve Hooper and I spent a clear cold evening recording the stars over Monadnock from the lovely home of friends in Marlborough New Hampshire. Over about 2 hours we record more than 200 images and after processing we were rewarded with about 13 seconds of a dramatic moving star field video. Unfortunately the lower resolution video here does not reflect the impact of the full resolution version.
Star Track Photography
|Back Porch Star Tracks Chesterfield NH|
Over prolonged exposures digital sensors heat up and the result can be increasing amounts of distracting noise. The severity of the problem varies with different cameras but with longer exposures it becomes a issue for them all. The digital solution is to take multiple images and combine them into a single picture using stacking, blending the layers to create a array of smooth continuous arcs. In my examples, I created the star track by using a selection of the images originally collected for the moving star fields. I experimented with the number of images, fewer creating a less densely packed sky as in the tracks over Monadnock. In the tracks over my back porch, more images created a much busier perspective.
The procedure starts with collecting multiple sky images. I hope I don't have to mention that a tripod is a necessity - don't be offended. You want a clear sky without a great deal of light pollution or intrusion of the moon, but some foreground elements can provide pleasant framing and context.
With the camera on manual you can experiment with exposure. Longer exposures will cut down the number of images required and increase the number of visible stars. The nice thing about the multiple-image approach is that, when you get home you can fine tune the final image by adjusting the brightness and the number of
|Beaded Star Tracks with 10 Second Pauses |
Once home I pull up all of my images in Adobe Bridge;
|Edit Single Image in Adobe bridge|
|Load Images Into a Stack of Layers|
|Apply "Lighten" Blending Option to each layer|
Once I am pleased with the blended image, I flatten the file and can
|Plane Trails from Boston|
|Star Tracks over Monadnock (Cleaned)|
Less Densely Packed
That's about it. Not too complicated, but with impressive and unique results. Just a couple of other technical points. First if you plan to record many images over an extended period of time you should be sure to use a fresh battery. This is especially important when you are out in the cold. Once you have all the settings locked in, switching off the camera's LCD monitor can extend battery life. If you decide to get a intervalometer you will find that the official Manufacturer versions are quite expensive. The Canon intervalometer is $135, but you can get knock-offs for around $30 that look and work the same. My intervalometer came from China, it cost $25 and has worked without any problems.
So get out on the next clear dark evening and give star photography a try. There is a lot to learn and I feel I am just beginning. As spring arrives it will be much less uncomfortable and we can come home with something truly special.