Star Trail Photo Simulates Long Exposure

*LeoTaylor* · 03-23-2009, 12:43 PM

Awhile back there was a thread about using a program from Germany called Startrails (www.Startrails.de) to simulate long exposures of the night sky. At the time I had nothing longer than 30 minutes to show. It took this long for me to be at a dark site with a clear sky. Star Trails are intolerant of even a single passing cloud.

This was taken at a Boy Scout Camp in Goshen CT. I waited until the Scouts were asleep. The camera took 212 thirty second exposures using a Pentax K100D, Vivitar 19mm F3.5 lens, Bogan tripod, Pentax AC supply, and Pentax manual cable release. I set the camera to Manual, Continuous, no NR, and locked the remote. I then went off to do some imaging with my K110D. This is just shy of a two hour exposure during which the Earth rotated 30 degrees. Long exposures bring out the color in stars.

Things I could have done better would be to include some foreground scenery and take some dark frames. It was 3 AM, I wasn't thinking clearly.

This type of photography is easy to do once you have a dark location to set up. I should note with this wide lens NO stars appeared in the viewfinder or LCD display. The sharp dots are too small to see without Zoom. I had to focus by setting the lens to infinity which would not be accurate enough for a longer focal length lens.

Jim Royal · 03-23-2009, 01:08 PM

Great shot. I had never considered the idea of multiple long exposures combined into one massive long exposure. It suggests possibilities other than star trails, too.

About the wiggle at the clockwise end of the trails... that happened at the end of the sequence?

*LeoTaylor* · 03-26-2009, 11:40 AM

Originally Posted by Jim Royal

About the wiggle at the clockwise end of the trails... that happened at the end of the sequence?

I was hoping no one would ask that.

I don't know. The camera seems to have shifted diagonally, the curl appears in the upper right and lower left. The tripod was unattended for all but the first and last frame, No one was in that area of the camp. My only guess is the ground was muddy when I set up and frozen solid when I returned. Perhaps a leg of the tripod moved slightly as the mud froze. That could cause a diagonal movement.

The longest single frame star trail I've taken was 20 minutes with a K1000 in 2002. That was only 5 degree rotation and still the sky glow was bright. Same manual focus 19mm lens!

*heliphoto* · 03-26-2009, 11:58 AM

Originally Posted by LeoTaylor

I was hoping no one would ask that.

I don't know. The camera seems to have shifted diagonally, the curl appears in the upper right and lower left. The tripod was unattended for all but the first and last frame, No one was in that area of the camp. My only guess is the ground was muddy when I set up and frozen solid when I returned. Perhaps a leg of the tripod moved slightly as the mud froze. That could cause a diagonal movement.
...

Funny - I've never had to worry about frost heave in any of my photography

. Cool star trails - someday I'll do this. Seems like a good use for the interval feature on my K20D.

*LeoTaylor* · 03-26-2009, 07:04 PM

Originally Posted by heliphoto

... Seems like a good use for the interval feature on my K20D.

The K20D Noise Reduction may bite you. I don't have one but understand from many threads on this forum that for long exposures that is the only Pentax DSLR that can't turn off NR.

Digitalis · 03-26-2009, 08:21 PM

yes, star trails can be a lot of fun...it's just a pain to get them focused correctly.