StarTrails
Glass Photography Blog
February 14, 2025
Recipe: Photographing Star Trails
The story:
It’s a dark night – really dark. I’m fumbling with camera settings, when something pounces on my back. I’m in the middle of a meadow; it’s about 15 degrees, pitch black with the exception of the red glow of my headlamp. Adrenalin surges through my veins, as images of a mountain lion dismembering my gut cavity flash through my mind. I drop to my knees, swing around, and bring my arms up into the fight position to protect my jugular while simultaneously bumping my tripod, when laughing - lots of laughing - cuts through my terror and I hear, “It’s one of the cats, Dad! He wants to be petted!” My mind calms and I know I’ll live through the night. Yes, it’s another day in the Life of a Wander, Wondering, Wow-filled Photographer – 19 plus years as a professional – and still going strong.
Once the cortisol is absorbed and I realize I’m not about to be ingested and then digested by a mountain lion, I set back to the task at hand – Star Trails.
Star Trails are an amazing way to compress the movement of the earth into a single moment, by recording the streaks of light that are left imprinted on the camera’s sensor from the glorious - perfectly orchestrated spin of the earth at a mind bending 1525 feet per second or roughly 1000 mph (as measured at the equator). And while we stand, with our camera pointing toward the heavens, locked down in the cradle of a tripod head, the earth does the heavy lifting – all the lifting – and records the brilliant rotation of our home. What’s left, when properly orchestrated . . . the capturing of elapsed time, compressed into a single image – often a very stunning image – and at the very least an interesting image.
So, how do you do this? What’s the recipe?
First, before answering that question, we must determine – is this the quick bake or the long bake? In Star Trails, there are two main recipes - a single exposure recipe and multiple exposure recipe.
We’ll cover the multiple exposure Star Trail Recipe.
The Multiple Exposure Recipe has some advantages which is why we are going to explore this option.
1. Multiple exposures lets you remove a bad exposure. So, for example, when the mountain lion attacks and you bump the tripod and you realize it’s just a house cat, no problem – the one bad frame . . . just omit it. BTW, notice the silhouette of the mountain lion?
2. You can determine the ideal amount of trail that you want. Do you want a full circle? Partial circle? Decide after the fact.
3. Creating a strong foreground image and balancing the foreground with the background is much easier, when you approach the creation of both images independently. Foreground image created first; star trail image created second.
4. Your sensor won’t get too hot (not a problem for my artic photographer friends) thus noise will be limited. You can keep shooting for hours, hours, hours and hours – no overheating sensors.
5. Noise will not be an issue at mere 30 second exposures, especially when the ISO is 640, like in this shot.
6. Leave your tripod and camera; go grab a snack, a drink, a nap . . . . and when you come back you don’t have to worry about your headlamp effecting a few frames, whereas with a single exposure imagine ruining a hard-won two-hour shot by accidentally shining your headlamp onto the front element of the lens. Can you say, “Cry?” Not a problem with this method!
Recipe - Star Trail (Multiple Exposure)
Yields - At least 1 Jaw Dropping Piping Hot Star Trailscape.
Ingredients
- Clear Night Sky, add spice by having interesting foregrounds.
- Tripod & Head
- Older than dirt aluminum Manfrotto Sticks
- Real Right Stuff 55 Ball Head with screw nob release
- Mirrorless Camera
- Canon R6 Mark I
- Wide Angle Lens
- Canon EF 16-35mm f/2.8L I USM + Canon EF to RF adapter (i.e. EF to mirrorless lens adapter). Yes, version 1, can you say twenty years old years old baby!
- Canon EF 24-70mm f/2.8L II USM + EF to RF Canon adapter (i.e. EF to mirrorless lens adapter).
- Intervalometer
- Built into the Canon R6 Mark 1
- Headlamp
- • Handwarmers
Optional Ingredients
- Lens Strap Heater (keeps condensation off the lens)
- Good friend to keep you company
- No friend, then a sleeping bag to take a nap in. Remember I shot this in the winter.
- Coffee
- Maybe a little Irish Cream for that coffee – if you’re in walking distance to your lodging.
Mise En Place (pre-cook preparation):
Before the big night, during warm daylight hours, learn the details of your intravalometer. On the Canon R6 Mark I, this is built-in – no extra cords nor remotes needed. Set your intravalometer to take between 50-300 photos; or more, if you are feeling really crazy. And then keep the time between photos as short as possible (1 second or less is ideal). If you are using a fast modern lens, I recommend shooting fully open (i.e. f/2.8) with your shutter speed set at 30 seconds. Since my version 1, Canon EF 16-35mm L USM, is 20 years old, it is a little soft on the edges when shot wide open, so I stopped down to f/4. If I was shooting the new RF 15-35 f/2.8 L, I’d almost certainly be shooting wide open. I’d test with my ISO at 640, check the histogram and preview the images to make sure the stars are clearly being recorded as white little spots. Then, depending on the results or the preview and the histogram, I would increase or decrease my ISO.
Preheat (camera settings):
File Type: RAW
Long Noise Exposure: Turn Off
Exposure: Start at 30 seconds, f/2.8 – f/4 (depending on lens), corresponding ISO 640.
Adjust ISO as needed to achieve clearly registered stars and histogram. Please note, ISO can be increased or decreased depending on ambient light. The main variables that will affect the ambient light is the moon phase (its current luminosity), shooting time in proximity to dawn or dusk (i.e. civil twilight), and city lights.
Caption: Screen Shot: Lightroom CC, RAW photo (no adjustments).
Just pin pricks of light. Please note: I could have increased the ISO just slightly for better registered stars.
30 seconds @ f/4, ISO 640. Canon EF 24-70mm f/2.8L II USM (with Canon EF to RF Adapter)
Caption: Screen shot from Lightroom CC.
Notice how there’s hardly anything registering. Just bits of light. Please note, this was a new moon night (no moon) and it was very dark. On a full moon night this will shift right as the foreground picks up more light.
Cook Time (Taking the images):
Once the exposure has been set, now it’s time to use the intravalometer. Using the tested exposure, take a minimum of 50 frames with one second gaps. For the below shot, I used about 200 frames, which took about 100 minutes.
Let the Meat Rest (post processing):
Import into Lightroom.
1. In Grid mode, select the images you want to create your Star Trail. Right click the selection, go to “Edit In”, then to the fly out menu “Open as Layers in Photoshop.”
a. You can see in this image, I’m using 201 base images, circled in red.
Caption: Screen shot from Lightroom CC.
2. In Photoshop, let’s deal with layers. Really, I promise this easy – you can do it!
Caption: Screen shot from Lightroom CC.
Select all layers (Shift +Alt). Change Blend Mode to Lighten. Ta Da! You now have star trails.
3. Flatten Image. Clean out unwanted lights (plane lights). Then save image as a Photoshop file (.psd file).
4. Open the file in Lightroom and process to your taste. I mainly use the Exposure tab, Color Temperature, White and Black settings.
Caption: Screen shot from Lightroom CC.
Star Trails - done!
Now you are going to notice the gaps between stars, especially when you zoom to 100%. How do you get rid of those? There’s not a great solution . . . so I’m going to leave them.
However, if you are curious, you may want to know what formed those gaps. At first glance, one might assume they are from the intravolometer 1 second gap between each exposure. They’re actually not; they’re from “rounding” from the image processor in your camera. There is a fascinating article that explains why these gaps are formed:
https://jmlobert.blogspot.com/2016/09/debunking-myth-about-star-trail-gaps.html
How do you completely eliminate these gaps? Well . . . I have yet to find a great solution – just partial solutions. Nothing mind bending . . . so currently I’m leaving the gaps. If you have any insight, please let me know - I’d love to hear.
Now, one last step. Bring in the foreground image (I’ll discuss making foreground shots in a future article) and your star trail image into two separate Layers in Photoshop. Mask in the sky (or foreground – depending on how you stack your Layers) and viola! You’ve done it. An amazing Star Trail Image.
Do you want to learn how to photograph Star Trails in-person? Come join us at our Cowboys in Colorado Workshop.