Star Trails Print

My son-in-law Duane did some extensive research on star trails photography before we went to Joshua Tree in October for the rock climbing trip with Christopher and other boys his age.  We fooled around with it on that trip (I failed miserably) and had to go back for another try.  This time, Duane had done even more research to solve the problem of power.  Our results were vastly improved.

In the old days (aka, film) astro photographers could set a camera on a tripod and open the shutter for, say, four hours and get a cool exposure that showed star trails in the sky because of the earth's rotation during the exposure.  You can't do that with a digital camera because the sensor "blooms" and absorbs way too much light and extraneous detail.

Note:  with the exception of the Power Pack photo, if you click on any thumbnail in this article it will open to a larger image.

The technique in today's world of pro-DSLR cameras is to take hundreds--or as many as your battery will allow--of photos and combine them into one frame.  This, of course, is easier said than done.  To take hundreds of photos you would have to stand next to your tripod-mounted camera and press your remote release button hundreds of times--or, set it up to do so itself and go to bed.  Either way, you need enormous battery life.

We used as a basis for technique an article written by Moose Peterson called "Lights of the Heavens" that has great information on the subject.  Duane and I read through this carefully, we both bought intervalometers (Nikon MC-36) and we set our cameras with the settings shown in Moose's article.  Unfortunately, it didn't work.  Duane figured out that the "interval" setting seemed wrong;  it needs to be what your "long" setting is, plus 1 or 2 seconds.  So, we tried that the next night and it was better,  but our batteries petered out after an hour or so.

After we returned, Duane investigated options for power and discovered the 5-In-One Portable Power Packon the Harbor Tools web site. It's basically a sealed car battery with two DC sockets on one side and two AC sockets with an inverter on the other side.  powerpack.jpgWe each bought one because it's the ideal solution for the problem.  Plus, it's a handy thing to have around for power outages;  it has a work light that will illuminate a sizable area and you can plug in two AC-driven devices and two DC-driven devices. This means that you must have an AC-adapter for your camera.  So, I now have two each Nikon EH-6A power packs to drive my D2X and my D3, along with two each Nikon MC-36 intervalometers.  Expensive hobby, this photography thing.

Anyway, armed with cameras, lenses, power packs, intervalometers, tripods, sleeping bags, a tent, and (for Duane and me) dry-aged New York steaks, and some asparagus soaking in water and olive oil, we drove out to Joshua Tree for the night.  John Bohner and Robert Vlach joined us.  We set up the tent and set about making small talk while Duane started a charcoal file in the grill pit.  After some excellent beer I grilled the steaks and asparagus for Duane and me, which we enjoyed with some syrah, and we continued to talk about technique for this exercise we were about to undertake.

This rather crude photo, which I took with my point-and-shoot the next morning, shows my D2X and D3 mounted on their tripods, with the intervalometers and AC cords dangling about, and the Power Pack on the table.  The D3 is pointed north way up into the sky;  the D2X is pointed south.

We spent a fair amount of time after dinner experimenting with timing and ISO settings to determine what we thought the optimum exposure would be.  I decided on ISO 400 and exposures of 40 seconds.  This had as much to do with image quality as it did the total time involved;  I wanted plenty of earth rotation and I wanted lots of photos.  I set both intervalometers for "long" settings of 40 seconds and "interval" settings of 42 seconds. I set the D2X for 380 images and the D3 for 350. I put my14-24mm lens on the D2X and my 24-70mm lens on the D3, set them both on f/2.8, set the focus to manual and put both lenses on infinity, started both intervalometers and went to bed with my fingers crossed.

I was much more successful this time, as you can see below.  Having over 700 photographs in hand, then began the process of converting them to usable images.  It still amuses me that I went out there and took that many photographs, knowing full well that the best I could possibly do was to get two images.  In Moose's article, he mentions three different software packages that are designed for stacking images into one frame.  We're using Startrails because it's free and it works well.

This image from the D3 shows what happens when you point north way up in the sky.  It's cool but would be better with a foreground element and full circle, which Duane captured.  

I was more pleased with the D2X image because I had included some of the rock formations in front.  Pointing south gives you different kinds of trails.  I left these in color (and applied the Pro Contrast filter from Nik Color Efex Pro) because I think the colors are really cool:

I got up in time for sunrise, which was really lovely, and took this photo with the D3 before we started breaking camp to come home.

All in all, a great guy trip, enhanced by spending some more time with Duane and with two other photography friends.  Yes, we're going to do it again.  It's SUCH FUN.

P.S.-- Here are the prep notes I keep as a Note in my iPhone:


Star Trails Photography


1. Plug an MC-36 into the 10-pin connector

     MC-36 programming:

     Delay = 00:00:00

     LONG = 00:00:40

     INTVL = 00:00:41

     Set number of photographs to 350


2. Plug EH-6A AC power adapter into camera and connect to Power Pack

3. Turn long exposure noise reduction off

4. Put a bubble level in the hotshoe and level the horizon if necessary

5. Set ISO to 400

6. Use f/2.8 or widest available

7. Turn autofocus OFF

8. Set focus on INFINITY

9. Set shutter speed to BULB

10. After setting up composition, close the viewfinder shutter; if none available, tape over viewfinder

11. Start the intervalometer, start the inverter on the Power Pack, and go to bed

12. If painting a foreground element, do so during the first one or two frames only