The Evolution of a Stargazer

Gary Hart Photography: Dark Sky, Milky Way Above the Colorado River, Grand Canyon

Dark Sky, Milky Way Above the Colorado River, Grand Canyon
Sony a7SII
Sony 24 f/1.4 GM
20 seconds
F/1.4
ISO 6400

In the Beginning

I grew up in a camping family. My dad was a minister, so pricey airline/hotel/restaurant vacations were out of the question for the five of us, as of course were weekend camping trips. But for as far back as I can remember, each summer my family went camping somewhere. Usually it was a week or two in Yosemite, Sequoia/Kings Canyon, the California coast, or some other relatively close scenic destination, but every few years we’d hook up the tent trailer, pile into the station wagon, and take a road trip.

The one constant in this numbing succession of summer campsites was the dark sky far from city lights, and the vast sprinkle of stars that mesmerized me. I soon learned that stargazing is the one thing a child can do for as long as he wants after bedtime without getting in trouble. I enjoyed playing connect-the-dots with the stars, identifying named constellations, or making up my own. It turned out all this scanning was a great way to catch shooting stars, and soon my goal was to stay awake until one flashed across my vision. And satellites were still something of a novelty back then, so another camping bedtime exercise was to slowly scan the sky looking for a “star” that moved; when I found one, I’d track it across the until it disappeared behind the horizon—or my eyelids.

At some point I became aware of a hazy band of light stretching across my night sky. On the darkest nights, when my vantage point faced the right direction, the widest and brightest part of this band reminded me of sugar spilled on pooled ink. But the Milky Way wasn’t as dramatic some of the other stuff in my night skies, so the childhood Me was oblivious to its inherent coolness for many years.

On these nightly scans I was more interested in the apparent randomness in the patterns overhead—the consistency of certain stellar arrangements, while a few bright “stars” would be in different positions each night relative to these recognizable patterns. Someone explained to me the difference between stars and planets, that stars were far and planets were close, and that was good enough for me. For a while.

Then, when I was about ten, my best friend and I did a science project on comets, which ignited a sudden and intense interest in all things astronomical. I was gifted a second-hand telescope by a friend of my dad, which we’d set up in my best friend’s front yard on summer nights. Through the telescope the stars remained (boring) points of light, no matter how much I magnified them, but the planets became fascinating disks, each with its own personality. I learned that Venus and Mercury were actually crescents of varying size, just like a mini moon. After searching in vain for the canals on Mars, I was thrilled to (barely) see Saturn’s rings, and to watch the nightly dance of the four pin-prick Galilean moons.

All this stargazing helped me develop a rudimentary understanding of celestial relationships, the vastness of space, the sun’s dominant role in our solar system, and its utter insignificance in the Universe. And the more I learned about astronomy, the more fascinating our home galaxy became. Rather than just passively observing it, the Milky Way became a catalyst for pondering the mysteries of the Universe and my favorite night sky feature.

Fast forward…

Then came college, marriage, family, jobs, cameras (lots of cameras) until I found myself at the bottom of the Grand Canyon on this moonless night in May. It was the second night of my annual Grand Canyon Raft Trip for Photographers, a highlight in a year full of highlights, and my first opportunity each year to reconnect with my favorite celestial feature. After night one hadn’t worked out, I told myself that we still had four more chances, but at bedtime on night two I was a little more pessimistic.

The prescription for a successful Milky Way photograph includes a clear view of the southern sky with a nice foreground. There’s no shortage of foreground in the Grand Canyon, but southern sky views are not quite so plentiful. The first night had been spectacularly clear, but our otherwise spectacular campsite was on an east/west trending section of river (I try to select each campsite for its astrophotography potential, but the sites can’t be reserved, and sometime there are other factors to consider), which placed the rising galactic core behind a towering canyon wall. On our second day we’d scored prime real estate on a north/south section of river a few miles upstream from Desert View, but now thin clouds threatened to spoil the show.

In May the Milky Way doesn’t usually crest the canyon walls until 2:00 or 3:00 a.m. (depending on the location), but as we prepared for bed that second day, only a handful of stars smoldered in the gauzy veil above. But with six hours for conditions to improve, I prepared anyway, identifying my foreground, setting up my tripod next to my cot, and mounting my Sony a7SII body and Sony 24mm f/1.4 lens with ISO, f-stop, and shutter speed set.

Waking a little before 3:00, I instantly saw far more stars than had been visible at bedtime. But more importantly, there was the Milky Way, directly overhead. I sat up and peered toward the river—the soft glow of several LCD screens told me others were already shooting, so I grabbed my tripod and stumbled down to the river’s edge in the dark (to avoid illuminating the others’ scene). It’s quite amazing how well you can see by the light of the Milky Way once your eyes adjust.

After a few frames I saw that a few thin clouds remained, creating interesting patterns against the starry background. By about 4 a.m., an hour-and-a-half before sunrise, loss of contrast in my images that wasn’t visible to my eyes told me the approaching sun was already starting to brighten the sky. I photographed for about an hour that morning, then managed to catch another 45 minutes of contented sleep before the guides’ coffee call got me up for good.

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I continue updating my Photo Tips articles—here’s my just-updated Milky Way article,

with all you need to know to locate and photograph our home galaxy


How to photograph the Milky Way

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See the Milky Way

Look heavenward on a moonless (Northern Hemisphere) summer night far from city light. The first thing to strike you is the shear volume of stars, but as your eyes adjust, your gaze is drawn to a luminous band spanning the sky. Ranging from magnificently brilliant to faintly visible, this is the Milky Way, home to our sun and nearly a half trillion other stars of varying age, size, and temperature.

Size and shape

Though every star you’ve ever seen is part of our Milky Way galaxy, stargazers use the Milky Way label more specifically to identify this river of starlight, gas, and dust spanning the night sky. As you feast your eyes, appreciate that some of the Milky Way’s starlight has traveled 25,000 years to reach your eyes, and light from a star on one edge of the Milky Way would take 100,000 years to reach the other side.

Spiral Galaxy (Milky look-alike): This is what our galaxy would look like from above.

Milky Way look-alike spiral galaxy: This is what our galaxy would look like from the outside, looking in. (The individual stars visible here are “local” and not part of the spiral galaxy depicted here.) Earth would be between two of the spiral arms, about halfway out from the center.

The rest of the sky appears to be filled with far more discrete stars than the region containing the Milky Way, but don’t let this deceive you. Imagine that you’re out in the countryside where the lights of a distant city blend into a homogeneous glow—similarly, the stars in the Milky Way’s luminous band are simply too numerous and distant to resolve individually. On the other hand, the individual pinpoints of starlight that we name and mentally assemble into constellations are just closer, much like the lights of nearby farmhouses. And the dark patches in the Milky Way aren’t empty space—like the trees and mountains that block our view of the city, they’re starlight-blocking interstellar dust and gas, remnants of exploded stars and the stuff of future stars.

Just as it’s impossible to know what your house looks like by peering out a window, it’s impossible to know what the Milky Way looks like by simply looking up on a dark night. Fortunate for us, really smart people have been able to infer from painstaking observation, measurement, reconstruction, and comparison with other galaxies that our Milky Way is flat (much wider than it is tall) and spiral shaped, like a glowing pinwheel, with two major arms and several minor arms spiraling out from its center. Our solar system is in one of the Milky Way’s minor arms, a little past midway between the center and outer edge.

Blinded by the light

Sadly, artificial light and atmospheric pollution have erased the view of the Milky Way for nearly a third of the world’s population, and eighty percent of Americans. Worse still, even though some part of the Milky Way is overhead on every clear night, many people have never seen it.

Advances in digital technology have spurred a night photography renaissance that has enabled the Milky Way challenged to enjoy images of its splendor from the comfort of their recliner, but there’s nothing quite like viewing it in person. With just a little knowledge and effort, you too can enjoy the Milky Way firsthand; add the right equipment and a little more knowledge, and you’ll be able to photograph it as well.

Horizon to Horizon

Understanding that our Solar System is inside the Milky Way’s disk makes it easier to understand why we can see some portion of the Milky Way on any night (assuming the sky is dark enough). In fact, from our perspective, the plane of the Milky Way forms a complete ring around Earth (but of course we can only see half the sky at any given time), with its brightness varying depending on whether we’re looking toward our galaxy’s dense center or sparse outer region.

Where the action is

Milky Way and Halemaʻumaʻu Crater, Kilauea, Hawaii

The Milky Way’s brilliant center, its “galactic core,” radiates above Kilauea on Hawaii’s Big Island

Though the plane of the Milky Way stretches all the way across our sky, when photographers talk about photographing the Milky Way, they usually mean the galactic core—the Milky Way’s center and most densely packed, brightest region. Unfortunately, our night sky doesn’t always face the galactic core, and there are many months when this bright region is not visible at all.

To understand the Milky Way’s visibility in our night sky, it helps to remember that Earth both rotates on its axis (a day), and revolves around the sun (a year). When the side of the planet we’re on rotates away from the sun each day, the night sky we see is determined by our position on our annual trip around the sun—when Earth is between the sun and the galactic core, we’re in position to see the most brilliant part of the Milky Way; in the months when the sun is between earth and the galactic core, the bright part of the Milky Way can’t be seen.

Put in terrestrial terms, imagine you’re at the neighborhood playground, riding a merry-go-round beneath a towering oak tree. You face outward, with your back to the merry-go-round’s center post. As the merry-go-round spins, your view changes—about half of the time you’d rotate to face the oak’s trunk, and about half the time your back is to the tree. Our solar system is like that merry-go-round: the center post is the sun, the Milky Way is the tree, and in the year it takes our celestial merry-go-round to make a complete circle, we’ll face the Milky Way about half the time.

Finding the Milky Way

Just like every other celestial object outside our solar system, the Milky Way’s position in our sky changes with the season and time of night you view it, but it remains constant relative to the other stars and constellations. This means you can find the Milky Way by simply locating any of the constellations in the galactic plane. Here’s an alphabetical list of the constellations* through which the Milky Way passes (with brief notes by a few of the more notable constellations):

  • Aquila
  • Ara
  • Auriga—faintest
  • Canis Major—faint
  • Carina
  • Cassiopeia—faint; its easily recognized “w” (or “m”) shape makes Cassiopeia a good landmark for locating the Milky Way in the northern sky
  • Cepheus
  • Circinus
  • Crux
  • Cygnus—bright
  • Gemini
  • Lacerta
  • Lupus
  • Monoceros
  • Musca
  • Norma
  • Ophiuchus
  • Orion—faint; another easy to recognize constellation that’s good for finding the galactic plane
  • Perseus—faint
  • Puppis
  • Pyxis
  • Sagitta
  • Sagittarius—brightest, galactic core
  • Scorpius—bright
  • Scutum
  • Serpens
  • Taurus—faint
  • Triangulum
  • Vela
  • Vulpecula
* Constellations are comprised of stars that only appear connected by virtue of our Earth-bound perspective—a constellation is a direction in the sky, not a location in space.

If you can find any of these constellations, you’re looking in the direction of some part of the Milky Way (if you can’t see it, your sky isn’t dark enough). But most of us want to see the center of the Milky Way, where it’s brightest, most expansive, and most photogenic. The two most important things to understand about finding the Milky Way’s brilliant center are:

  • From our perspective here on Earth, the galactic core is in Sagittarius (and a couple of other constellations near Sagittarius)—when Sagittarius is visible, so is the brightest part of the Milky Way (assuming you can find a dark enough sky)
  • Earth’s night side most directly faces Sagittarius in the Northern Hemisphere’s summer months (plus part of spring and autumn)

Armed with this knowledge, locating the Milky Way’s core is as simple as opening one of my (too many) star apps to find out where Sagittarius is. Problem solved. Of course it helps to know that the months when the galactic core rises highest and is visible longest are June, July, and August, and to not even consider looking before mid-March, or after mid-October. If you can’t wait until summer and don’t mind missing a little sleep, starting in April, Northern Hemisphere residents with a dark enough sky can catch Sagittarius and the galactic core rising in the southeast shortly before sunrise. After its annual premier in April, the Milky Way’s core rises slightly earlier each night and is eventually well above the horizon by nightfall.

People who enjoy sleep prefer doing their Milky Way hunting in late summer and early autumn, when the galactic core has been above the horizon for most of the daylight hours, but remains high in the southwest sky as soon as the post-sunset sky darkens enough for the stars to appear. The farther into summer and autumn you get, the closer to setting beneath the western horizon the Milky Way will be at sunset, and the less time you’ll have before it disappears.

Into the darkness

The Milky Way is dim enough to be easily washed out by light pollution and moonlight, so the darker your sky, the more visible the Milky Way will be. To ensure sufficient darkness, I target moonless hours, from an hour or so after sunset to an hour before sunrise. New moon nights are easiest because the new moon rises and sets (more or less) with the sun and there’s no moon all night. But on any night, if you pick a time before the moon rises, or after it sets, you should be fine. Be aware that the closer the moon is to full, the greater the potential for its glow to leak into the scene from below the horizon.

Getting away from city lights can be surprisingly difficult (and frustrating). Taking a drive out into the countryside near home is better than nothing, and while it may seem dark enough to your eyes, a night exposure in an area that you expect to be dark enough reveals just how insidious light pollution is as soon as you realize all of your images are washed out by an unnatural glow on the horizon. Since the galactic core is in the southern sky in the Northern Hemisphere, you can mitigate urban glow in your Milky Way images by heading south of any nearby population area, putting the glow behind you as you face the Milky Way.

Better than a night drive out to the country, plan a trip to a location with a truly dark sky. For this, those in the less densely populated western US have an advantage. The best resource for finding world-class dark skies anywhere on Earth is the International Dark-Sky Association. More than just a resource, the IDA actively advocates for dark skies, so if the quality of our night skies matters to you, spend some time on their site, get involved, and share their website with others.

Photograph the Milky Way

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Viewing the Milky Way requires nothing more than a clear, dark sky. (Assuming clean, clear skies) the Milky Way’s luminosity is fixed, so our ability to see it is largely a function of the darkness of the surrounding sky—the darker the sky, the better the Milky Way stands out. But because our eyes can only take in a fixed amount of light, there’s a ceiling on our ability to view the Milky Way with the unaided eye.

A camera, on the other hand, can accumulate light for a virtually unlimited duration. This, combined with technological advances that continue increasing the light sensitivity of digital sensors, means that when it comes to photographing the Milky Way, well…, the sky’s the limit. As glorious as it is to view the Milky Way with the unaided eye, a camera will show you detail and color your eyes can’t see.

Knowing when and where to view the Milky Way is a great start, but photographing the Milky Way requires a combination of equipment, skill, and experience that doesn’t just happen overnight (so to speak). But Milky Way photography doesn’t need to break the bank, and it’s not rocket science.

Equipment

Bottom line, photographing the Milky Way is all about maximizing your ability to collect light: long exposures, fast lenses, high ISO.

Camera

In general, the larger your camera’s sensor and photosites (the “pixels” that capture the light), the more efficiently it collects light. Because other technology is involved, there’s not an absolute correlation between sensor and pixel size and light gathering capability, but a small, densely packed sensor almost certainly rules out your smartphone and point-and-shoot cameras for anything more than a fuzzy snap of the Milky Way. At the very least you’ll want a mirrorless or DSLR camera with an APS-C (1.5/1.6 crop) size sensor. Better still is a full frame mirrorless or DSLR camera. (A 4/3 Olympus or Panasonic sensor might work, but as great as these cameras are for some things, high ISO photography isn’t their strength.

Another general rule is that the newer the technology, the better it will perform in low light. Even with their smaller, more densely packed sensors, many of today’s top APS-C bodies outperform in low light full frame bodies that have been out for a few years, so full frame or APS-C, if your camera is relatively new, it will probably do the job.

If you’re shopping for a new camera and think night photography might be in your future, compare your potential cameras’ high ISO capabilities—not their maximum ISO. Read reviews by credible sources like DP Review, Imaging Resource, or DxOMark (among many others) to see how your camera candidates fare in objective tests.

An often overlooked consideration is the camera’s ability to focus in extreme low light. Autofocusing on the stars or landscape will be difficult to impossible, and you’ll not be able to see well enough through a DSLR’s viewfinder to manually focus. Some bodies with a fast lens might autofocus on a bright star or planet, but it’s not something I’d count on (though I expect within a few years before this capability will become more common).

Having photographed for years with Sony and Canon, and working extensively with most other mirrorless and DSLR bodies in my workshops, I have lots of experience with cameras from many manufacturers. In my book, focus peaking makes mirrorless the clear winner for night focusing. Sony’s current mirrorless bodies (a7RII/RIII, a7S/SII) are by far the easiest I’ve ever used for focusing in the dark—what took a minute or more with my Canon, I can do in seconds using focus peaking with my Sony bodies (especially the S bodies). I use the Sony a7SII, but when I don’t want to travel with a body I only use for night photography, the Sony a7RIII does the job too. Of the major DSLR brands, I’ve found Canon’s superior LCD screen (as of 2019) makes it much easier to focus in extreme low light than Nikon. (More on focus later.)

Lens

Put simply, to photograph the Milky Way you want fast, wide glass—the faster the better. Fast to capture as much light as possible; wide to take in lots of sky. A faster lens also makes focus and composition easier because the larger aperture gathers more light. How fast? F/2.8 or faster—preferably faster. How wide? At least 28mm, and wider is better still. I do enough night photography that I have a dedicated, night-only lens—my original night lens was a Canon-mount Zeiss 28mm f/2; my current night lens is the Sony 24mm f/1.4.

Tripod

It goes without saying that at exposure times up to 30 seconds, you’ll need a sturdy tripod and head for Milky Way photography. You don’t need to spend a fortune, but the more you spend, the happier you’ll be in the long run (trust me). Carbon fiber provides the best combination of strength, vibration reduction, and light weight, but a sturdy (albeit heavy) aluminum tripod will do the job.

An extended centerpost is not terribly stable, and a non-extended centerpost limits your ability to spread the tripod’s legs and get low, so I avoid tripods with a centerpost. But if you have a sturdy tripod with a centerpost, don’t run out and purchase a new one—just don’t extend the centerpost when photographing at night.

Read my tips for purchasing a tripod here.

Other stuff

To eliminate the possibility of camera vibration I recommend a remote release; without a remote you’ll risk annoying all within earshot with your camera’s 2-second timer beep. You’ll want a flashlight or headlamp for the walk to and from the car, and your cell phone for light while shooting. And it’s never a bad idea to toss an extra battery in your pocket. And speaking of lights, never, never, NEVER use a red light for night photography (more on this later).

Getting the shot

Keep it simple

There are just so many things that can go wrong on a moonless night when there’s not enough light to see camera controls, the contents of your bag, and the tripod leg you’re about to trip over. After doing this for many years, both on my own and helping others in workshops, I’ve decided that simplicity is essential.

Simplicity starts with paring down to the absolute minimum camera gear: a sturdy tripod, one body, one lens, and a remote release (plus an extra battery in my pocket). Everything else stays at home, in the car, or if I’m staying out after a sunset shoot, in my bag.

Upon arrival at my night photography destination, I extract my tripod, camera, lens (don’t forget to remove the polarizer), and remote release. I connect the remote and mount my lens—if it’s a zoom I set the focal length at the lens’s widest—then set my exposure and focus (more on exposure and focus below). If I’m walking to my photo site, I carry the pre-exposed and focused camera on the tripod (I know this makes some people uncomfortable, but if you don’t trust your tripod head enough to hold onto your camera while you’re walking, it’s time for a new head), trying to keep the tripod as upright and stable as possible as I walk.

Flashlights/headlamps are essential for the walk/hike out to to and from my shooting location, but while I’m there and in shoot mode, it’s no flashlights, no exceptions. This is particularly important when I’m with a group. Not only does a flashlight inhibit your night vision, its light leaks into the frame of everyone who’s there. And while red lights may be better for your night vision and are great for telescope view, red light is especially insidious about leaking into everyone’s frame, so if you plan to take pictures, no red light! If you follow my no flashlight rule once the photography begins, you’ll be amazed at how well your eyes adjust. I can operate my camera’s controls in the dark—it’s not hard with a little practice, and well worth the effort to learn. If I ever do need to see my camera to adjust something, or if I need to see to move around, my cell phone screen (not the phone’s flashlight, just its illuminated screen) gives me all the light I need.

Composition

A good Milky Way image is distinguished from an ordinary Milky Way image by its foreground. Simply finding a location that’s dark enough to see the Milky Way is difficult enough; finding a dark location that also has a foreground worthy of pairing with the Milky Way usually takes a little planning.

Since the Milky Way’s center is in the southern sky (for Northern Hemisphere observers), I look for remote (away from light pollution) subjects that I can photograph while facing south (or southeast or southwest, depending on the month and time of night). Keep in mind that unless you have a ridiculous light gathering camera (like the Sony a7S or a7S II) and an extremely fast lens (f/2 or faster), your foreground will probably be more dark shape than detail. Water’s inherent reflectivity makes it a good foreground subject as well, especially if the water includes rocks or whitewater.

When I encounter a scene I deem photo worthy, not only do I try to determine its best light and moon rise/set possibilities, I also consider its potential as a Milky Way subject. Can I align it with the southern sky? Are there strong subjects that stand out against the sky? Is there water I can include in my frame?

I’ve found views of the Grand Canyon from the North Rim, the Kilauea Caldera, and the bristlecone pines in California’s White Mountains that work spectacularly. And its hard to beat the dark skies and breathtaking foreground possibilities at the bottom of the Grand Canyon. On the other hand, while Yosemite Valley has lots to love, you don’t see a lot of Milky Way images from Yosemite Valley because not only is there a lot of light pollution, and Yosemite’s towering, east/west trending granite walls give its south views an extremely high horizon that blocks much of the galactic core from the valley floor.

The last few years I’ve started photographing the Milky Way above the spectacular winter scenery of New Zealand’s South Island, where the skies are dark and the Milky Way is higher in the sky than it is in most of North America.

To maximize the amount of Milky Way in my frame, I generally (but not always) start with a vertical orientation that’s at least 2/3 sky. On the other hand, I do make sure to give myself more options with a few horizontal compositions as well. Given the near total darkness required of a Milky Way shoot, it’s often too dark to see well enough to compose that scene. If I can’t see well enough to compose I guess at a composition, take a short test exposure at an extreme (unusable) ISO to enable a relatively fast shutter speed (a few seconds), adjust the composition based on the image in the LCD, and repeat until I’m satisfied.

Focus

Needless to say, when it’s dark enough to view the Milky Way, there’s not enough light to autofocus (unless you have a rare camera/lens combo that can autofocus on a bright star and planet), or even to manually focus with confidence. And of all the things that can ruin a Milky Way image (not to mention an entire night), poor focus is number one. Not only is achieving focus difficult, it’s very easy to think you’re focused only to discover later that you just missed.

Because the Milky Way’s focus point is infinity, and you almost certainly won’t have enough light to stop down for more depth of field, your closest foreground subjects should be far enough away to be sharp when you’re wide open and focused at infinity. Before going out to shoot, find a hyperfocal app and plug in the values for your camera and lens at its widest aperture. Even though it’s technically possible to be sharp from half the hyperfocal distance to infinity, the kind of precise focus focusing on the hyperfocal point requires is difficult to impossible in the dark, so my rule of thumb is to make sure my closest subject is no closer than the hyperfocal distance.

For example, I know with my Sony 24mm f/1.4 wide open on my full frame Sony a7SII, the hyperfocal distance is about 50 feet. If I have a subject that’s closer (such as a bristlecone pine), I’ll pre-focus (before dark) on the hyperfocal distance, or shine a bright light on an object at the hyperfocal distance and focus there, but generally I make sure everything is at least 50 feet away. Read more about hyperfocal focus in my Depth of Field article.

By far the number one cause of night focus misses is the idea that you can just dial any lens to infinity; followed closely by the idea that focused at one focal length means focused at all focal lengths. Because when it comes to sharpness, almost isn’t good enough, if you have a zoom lens, don’t even think of trying to dial the focus ring to the end for infinity. And even for most prime lenses, the infinity point is a little short of all the way to the end, and can vary slightly with the temperature and f-stop. Of course if you know your lens well enough to be certain of its infinity point by feel (and are a risk taker), go for it. And that zoom lens that claims to be parfocal? While it’s possible that your zoom will hold focus throughout its entire focal range, regardless of what the manufacturer claims, I wouldn’t bet an entire shoot on it without testing first.

All this means that the only way to ensure night photography sharpness is to focus carefully on something before shooting, refocus every time your focal length changes, and check focus frequently by displaying and magnifying an image on your LCD. To simplify (there’s that word again), when using a zoom lens, I usually set the lens at its widest focal length, focus, verify sharpness, and (once I know I’m focused) never change the focal length again.

While the best way to ensure focus is to set your focal length and focus before it gets dark, sometimes pre-focusing isn’t possible, or for some reason you need to refocus after darkness falls. If I arrive at my destination in the dark, I autofocus on my headlights, a bright flashlight, or a laser 50 feet or more away. And again, never assume you’re sharp by looking at the image that pops up on the LCD when the exposure completes—always magnify your image and check it after you focus.

For more on focusing in the dark, including how to use stars to focus, read my Starlight Photo Tips article.

Exposure

Exposing a Milky Way image is wonderfully simple once you realize that you don’t have to meter—because you can’t (not enough light). Your goal is simply to capture as many photons as you can without damaging the image with noise, star motion, and lens flaws.

Basically, with today’s technology you can’t give a Milky Way image too much light—you’ll run into image quality problems before you overexpose a Milky Way image. In other words, capturing the amount of light required to overexpose a Milky Way image is only possible if you’ve chosen an ISO and/or shutter speed that significantly compromises the quality of the image with excessive noise and/or star motion.

In a perfect world, I’d take every image at ISO 100 and f/8—the best ISO and f-stop for my camera and lens. But that’s not possible when photographing in near total darkness—a usable Milky Way image requires exposure compromises. What kind of compromises? The key to getting a properly exposed Milky Way image is knowing how far you push your camera’s exposure settings before the light gained isn’t worth the diminished quality. Each exposure variable causes a different problem when pushed too far:

  • ISO: Raising ISO to increase light sensitivity comes with a corresponding increase in noise that muddies detail. The noise at any particular ISO varies greatly with the camera, so it’s essential to know your camera’s low-light capability(!). Some of the noise can be cleaned up with noise reduction software (I use Topaz DeNoise 6)—the amount that cleans up will depend on the noise reduction software you use, your skill using that software, and where the noise is (is it marring empty voids or spoiling essential detail?).
  • Shutter speed: The longer the shutter stays open, the more motion blur spreads the stars’ distinct pinpoints into streaks. I’m not a big fan of formulas that dictate star photography shutter speeds because I find them arbitrary and inflexible, and they fail to account for the fact that the amount of apparent stellar motion varies with the direction you’re composing (you’ll get less motion the closer to the north or south poles you’re aimed). My general shutter-speed rule of thumb is 30-seconds or less, preferably less—I won’t exceed 30 seconds, and do everything I can to get enough light with a faster shutter speed.
  • F-stop: At their widest apertures, lenses tend to lose sharpness (especially on the edges) and display optical flaws like comatic aberration (also called coma) that distorts points of light (like stars) into comet shaped blurs. For many lenses, stopping down even one stop from wide open significantly improves image quality.

Again: My approach to metering for the Milky Way is to give my scene as much light as I can without pushing the exposure compromises to a point I can’t live with. Where exactly is that point? Not only does that question require a subjective answer that varies with each camera body, lens, and scene, as technology improves, I’m less forgiving of exposure compromises than I once was. For example, when I started photographing the Milky Way with my Canon 1DS Mark III, the Milky Way scenes I could shoot were limited because my fastest wide lens was f/4 and I got too much noise when I pushed my ISO beyond 1600. This forced me compromise by shooting wide open with a 30-second shutter speed to achieve even marginal results. In fact, given these limitations, despite trying to photograph the Milky Way from many locations, when I started the only Milky Way foreground that worked well enough was Kilauea Caldera, because it was its own light source (an erupting volcano).

Today (mid-2019) I photograph the Milky Way with a Sony a7S II and a Sony 24mm f/1.4 lens. I get much cleaner images from my Sony at ISO 6400 than got a ISO 1600 on my Canon 1DSIII, and the night light gathering capability of an f/1.4 lens revelatory. At ISO 6400 (or higher) I can stop down slightly to eliminate lens aberrations (though I don’t seem to need to with the Sony lens), drop my shutter speed to 20 or 15 seconds to reduce star motion 33-50 percent, and still get usable foreground detail by starlight.

I can’t emphasize enough how important it is to know your camera’s and lens’s capabilities in low light, and how for you’re comfortable pushing the ISO and f-stop. For each of the night photography equipment combos I’ve used, I’ve established a general exposure upper threshold, rule-of-thumb compromise points for each exposure setting that I won’t exceed until I’ve reached the compromise threshold of the other exposure settings. For example, with my Sony a7SII/24mm f/1.4 combo, I usually start at ISO 6400, f/1.4, and 20 seconds. Those settings will usually get me enough light for Milky Way color and pretty good foreground detail. But if I want more light (for example, if I’m shooting into the black pit of the Grand Canyon from the canyon rim), my first exposure compromise might be to increase to ISO 12800; if I decide I need even more light, my next compromise is to bump my shutter speed to 30 seconds. Or if I want a wider field of view than 24mm, I’ll put on my Sony 16-35 f/2.8 G lens and increase to ISO 12800 and 30 seconds.

These thresholds are guidelines rather than hard-and-fast rules, and they apply to my preferences only—your results may vary. And though I’m pretty secure with this workflow, for each Milky Way composition I try a variety of exposure combinations before moving to another composition. Not only does this give me a range of options to choose between when I’m at home and reviewing my images on a big monitor, it also gives me more insight into my camera/lens capabilities, allowing me to refine my exposure compromise threshold points.

One other option that I’ve started applying automatically is long exposure noise reduction, which delivers a noticeable reduction in noise for exposures that are several seconds and longer.

* In normal situations the Sony a7SII can handle ISO 12,800 without even breathing hard, but the long exposure time required of night photography generates a lot of heat on the sensor with a corresponding increase in noise.

It’s time to click that shutter

You’re in position with the right gear, composed, focused, and exposure values set. Before you actually click the shutter, let me remind you of a couple of things you can do to ensure the best results: First, lower that center post. A tripod center post’s inherent instability is magnified during long exposures, not just by wind, but even by nearby footsteps, the press of the shutter button, and slap of the mirror (and sometimes it seems, by ghosts). And speaking of shutter clicks, you should be using a remote cable or two-second timer to eliminate the vibration imparted when your finger presses the shutter button.

When that first Milky Way image pops up on the LCD, it’s pretty exciting. So exciting in fact that sometimes you risk being lulled into a “Wow, this isn’t as hard as I expected” complacency. Even though you think everything’s perfect, don’t forget to review your image sharpness every few frames by displaying and magnifying and image on your LCD. In theory nothing should change unless you changed it, but in practice I’ve noticed an occasional inclination for focus to shift mysteriously between shots. Whether it’s slight temperature changes or an inadvertent nudge of the focus ring as you fumble with controls in the dark, you can file periodically checking your sharpness falls under “an ounce of prevention….” Believe me, this will save a lot of angst later.

And finally, don’t forget to play with different exposure settings for each composition. Not only does this give you more options, it also gives you more insight into your camera/lens combo’s low light capabilities.

The bottom line

Though having top-of-the-line, low-light equipment helps a lot, it’s not essential. If you have a full frame mirrorless or DSLR camera that’s less than five years old, and a lens that’s f/2.8 or faster, you probably have all the equipment you need to get great the Milky Way images. Even with a cropped sensor, or an f/4 lens, you have a good chance of getting usable Milky Way images in the right circumstances. If you’ve never photographed the Milky Way before, don’t expect perfection the first time out. What you can expect is improvement each time you go out as you learn the limitations of your equipment and identify your own exposure compromise thresholds. And success or failure, at the very least you’ll have spent a magnificent night under the stars.

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A Milky Way Gallery

Click an image for a closer look and slide show. Refresh the window to reorder the display.

9 Comments on “The Evolution of a Stargazer

  1. Great information, Gary. You walked us through this on the Big Island years ago, but it sure is nice to have the refresher. I plan on doing some night photography this summer since I now have an improved camera so this info goes right into my “how to” folder. Thank you! The night photos are beautiful and I always find value in your blog. I hope all is well with you!

  2. Beautiful shots, Gary, and one of the best, if not the best, tutorials on the subject I’ve ever read. It’s remarkably clear. Your writing background really comes to the fore. My main problem is that I have not been to places that have a great foregrounds. But I have practiced Milky Way shots just for gaining experience with exposure, focus, etc. I use a Tamron 15 – 30 mm F/2.8 on my Nikon D850. The D850’s low light capability is on a par with your Sony. Are use DxO PhotoLab for my RAW post processing. I have found its prime noise reduction to be absolutely astounding. It kills noise while preserving detail better than any other I’ve ever seen. Look forward to seeing you in Iceland next January. I suspect exposing for arora is a whole ’nother thing.

    • Thanks, Mike. Yeah, it takes a bit of effort to get to good Milky Way spots, but we in California have it better than those on the East Coast. Anywhere along the coast with a view to the south (not as hard to find as you might think) are good. And east of the Sierra is good too—the bristlecones and the Alabama Hills, to name just two of many.

      Though my primary body is the Sony a7RIII, which is great (among the best) in low light and very similar to the Nikon D850, my Milky Way body is the Sony a7SII, which is in fact the very best, at least a full stop better than the a7RIII and D850 (albeit with only 12 megapixels). And I agree completely with your assessment of DxO Prime Noise Reduction.

      Yes, the aurora is a completely different beast than the Milky Way, one where you constantly need to monitor your exposure to bring out the color or avoid blowing it out. I’m looking forward to Iceland too!

  3. Hey there G…wow, fabulous information. I’m wondering if a Dark Sky designated area would help in photographing the Milky Way during those October-March months?

    Thanks, GO

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