Experience with star trails

I'm going to be headed to Utah soon to hit some national parks, and I like to try some star trails. I'm going to shooting on Provia 100F. I did some research on the net and repeatedly came across exposure suggestions of f/5.6 - f/8 for 2 hours or more. I'm just looking for some advice about exposure from someone experienced with star trails. I'll be there during a new moon. One of the places I'll be visiting is Natural Bridges which is supposed to be a very dark area. Would it be better to open up the lens to say f/4 or even 2.8 since this is such a dark area? Thanks

I am not an expert on star trails. However I did some before. From what I remember f/5.6 - f/8 for 2 hours is not enough. I used C41 Reala probably at f2 for about 3 hours, and you got something like this.

I shoot star trails with the lens wide open (f/4 or 2.8). The amount of exposure will dictate the length of the star trails. Even a short 5 or 10 minute exposure will give short but effective star trails. Two hours or more will give rather long star trails, but lower the contrast (i.e., the trails will appear dim in the print). It comes down to what you want. If you have the time, shoot multiple shots doubling the exposure each time starting with 5 minutes. A new moon and a dark area sound good. If you want only star trails, then compose the shot without anything else in the frame. On the other hand, you might want to include a piece of the landscape in the frame. Or, you can shoot a few frames and do both. If there is a chance of vehicle lights falling on something in your shot, have a ball cap or something handy to cover the lens until the vehicle passes by. Be careful not to hit the camera.

The deeper the aperture, the more stars that will be visible. My standard procedure is 2.5 to 3 hours, f5.6 to f8, using Provia 100 in 35mm with a 24mm lens, unfiltered. Reciprocity failure will cast the photos you get, chiefly pinkish with Provia, green with Velvia, unearthly reddish hue with Velvia 100F and cool to cold blue with Tungsten (T64) film. Spoilt for choices, though Tungsten film is hard to get in 35mm. Star trails are experimental and a lot of fun: the fun comes out of not knowing exactly what you have until the film comes back! My first star trail (Yandoit, below) was surprisingly good despite having had a little too much wine with friends that night...

It was found during a trip into the outback here in Australia that the stars were absolutely beautiful to look at, but problems with the lens misting over in the very cold air and kangaroos or some other animal(s) bumping into the tripod caused some problems. I imagine The Arches National Park would be a stupendously beautiful place to set up star-trails, but do get some groundwork done in scouting around for important foreground subject e.g. one of the many arches, perhaps the star trails recorded with the arch "framing" the scene. Lots of possibilities obviously (my XP screensaver has 25 images of various US national Parks, Arches NP among them).

• Yandoit, central Victoria, February 2009: Southern Cross/South Celestial Pole
Provia 100, 2.5 hour exposure, Canon EOS1N f8, TS-E 24mm prime.




• Walker Creek, Cascade #7 (campsite in trees to left), Litchfield National Park, Northern Territory, Australia
While I was sound asleep...Unattended intervalometer image (2.30am), one of three. Velvia 100F
2.45 hour exposure under waning gibbous moon (hence the brightness); a few gusts of wind caught in trees.
Canon EOS1N with 17-40 f4L zoom (17mm), f6.7, unfiltered.
Camping here was adventurous: some quite big snakes active during the hot days (this pic shows my personal plunge-pool!) and nights,
the nights being a little troublesome from the bats, small animals and tree-climbing snakes.

Thanks for the help everyone! Really appreciate it.

To estimate the length of star trails, the earth turns 15 degrees in one hour.

To prevent condensation on the lens you can rig a small, cheap, battery-operated fan to your tripod to blow air across the front of the lens. I imagine even in summer the nights may be cool in Utah?