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As soon as I became enamored with long exposure film photography, I knew star trails were something I wanted to try. Why not marry my nerdy fascination with photography and my nerdy fascination with space?
But how do you get started when your exposures are several minutes to several hours, in conditions with so little light that a meter reading is useless?
Similar to starting out with long exposure photography, my first go at star trails was pretty experimental. I just went for it. I was at a friend’s cottage in the middle of a cold Canadian winter. The skies were dark, clear, and splattered with millions of stars. I set up my camera on a tripod down by the water (which was snow and ice at this point), decided that f/8 was a good enough aperture as any with 400 ISO film, set the shutter to Bulb, and started the exposure.
It was midnight at this point, and I didn’t feel like staying up for hours waiting for it to finish. So I went to bed, setting an alarm for 4:30am before the sun rose. The resulting four and a half hour exposure isn’t my favorite composition, but when I developed the film and saw I had star trails it was a win in my books.
Shooting Star Trails on Film vs Digital
Film is amazing stuff. Digital cameras have their perks, but, when it comes to star trails, film has some clear advantages.
Digital camera sensors and film are both super sensitive to light. They have to be to make an image. But when you’re talking about the lengthy exposures you need for star trails, digital sensors can actually be TOO sensitive. A digital sensor is just as sensitive to light after 1 second of exposure as it is after 5 minutes, meaning that with lengthy exposures you can overexpose the shot pretty quickly. Not to mention the sensor has a tendency to heat up during that time, resulting in unpleasant digital “noise” in the shot. There are ways to eliminate noise in post processing, and even create longer star trails by stacking digital images in Photoshop. But why go through all that when film can do it all in one go?
Yes, film is also really sensitive to light. But after about 1 second of exposure, film starts to slowly become less sensitive, a property called “reciprocity failure.” What this means for star trails is that film is capable of withstanding exposures of several hours with less risk of overexposing the image. The same digital exposure of 30 minutes might require 2 hours on film. And the longer the exposure, the longer the star trails.
Film does have its own version of “noise” (it’s called “grain”), and in a several hour exposure there’s going to be more of it. But compared to noise, grain is infinitely more pleasing, and to be honest, it gives the image a look I’ve always loved.
Equipment List for Star Trails
So what do you need to shoot star
trails on film? Here are a few necessities:
Film Camera – Make sure it’s fully manual with a Bulb (“B”) setting on the shutter.
Lens – The wider the better, but any focal length will “work.”
Tripod – Need to keep that camera steady to get sharp star trails.
Flashlight – For safety and for setting up your camera in the dark.
Clear, moonless night sky, with little light pollution – This might require some planning ahead, and a little bit of driving if you live in the city.
Settings for Shooting Star Trails
The hardest aspect of shooting star trails is knowing what settings to use. Like I said before, a light meter is useless because it’s too dark to get a reading anyways. But if you take anything from my blabbering about reciprocity failure, it’s that it’s pretty hard to overexpose your shot, especially if there are absolutely no other sources of light nearby.
If there is accidental light close by (for example a nearby city, or moonlight) be aware of where it is in your frame, since even light that seems dim to your eyes will build over time in your exposure. For example, the light from a nearby factory to the left of the frame in the windmill photo was hardly enough to make the windmill visible to my eyes in the dark, but the 45 minute exposure rendered it as if it was daytime.
I’ve only ever used 400 ISO black and white film for star trails, but I’ve seen successful images taken on 100-3200 ISO, so the film you choose isn’t crucial. For aperture, I usually stay between f/5.6 and f/8. I tried a 45 minute exposure at f/16 once to get a bit more foreground in focus, but it was pretty underexposed. Again, these settings can vary depending on how near you are to sources of light, so there will probably some trial and error involved.
Recommended Exposure Length
To get star trails of a decent length, I’ve found that you need to expose for at least 45 minutes to an hour. Any shorter and the effect isn’t as interesting in my opinion. Obviously the longer you expose, the longer the trails will be. If you’re lucky enough to live in the country you can sleep in a warm bed while the photo is exposing. Otherwise it might mean taking a nap in your car while you take the shot!
Focusing Your Lens for Star Trails
When setting up your lens, make sure
you focus to infinity. If you don’t know how, look on your lens
barrel for the infinity symbol (∞)
and line it up with the aperture you are using, or the top of the
lens. Without focusing to infinity your star trails won’t be sharp.
A Note on Composition
Thinking about composition, having a subject to contrast against the stars usually makes the image more interesting. Some knowledge of the night sky will also help you, in particular if you know how to find the North Star. All the other stars in the night sky will create circular trails around this point, which can make for some cool images.