Posted on March 10, 2019
With advanced exposure and metering capabilities, cameras seem to be getting “smarter” every year. So smart, in fact, that for most scenes, getting the exposure right is a simple matter of pointing your camera and clicking the shutter button. That’s fine if all you care about is recording a memory, but not only is there more to your exposure decision than getting the amount of light in your picture, there are many reasons to over- or underexpose a pictures. For the creative control that elevates your images above the millions of clicks being cranked out every day, giving control of one of its most important responsibilities to your camera overlooks an undeniable truth…
Your camera is stupid
Sorry—so is mine. And while I can easily cite many examples, right now it’s just important that you understand that your camera thinks the entire world is a middle tone. Regardless of what its meter sees, without intervention your camera will do everything in its power to make your picture a middle tone. Sunlit snowman? Lump of coal at the bottom of your Christmas stocking? It doesn’t matter—if you let your camera decide the exposure, it will turn out gray.
Modern technology offers faux-intelligence to help overcome this limitation. Usually called something like “matrix” or “evaluative” metering, this solution compares a scene to a large but finite internal database of choices, returning a metering decision based on the closest match. It works pretty well for conventional, “tourist” snaps, but often struggles in the warm or dramatic light artistic photographers prefer, and knows nothing of creativity. If you want to capture more than documentary “I was here” pictures, you’re much better off taking full control of your camera’s metering and exposure. Fortunately, this isn’t nearly as difficult as most people fear.
Laying the foundation
The amount of light captured for any given scene varies with the camera’s shutter speed, f-stop, and ISO settings. Photographers measure captured light in “stops,” much as a a cook uses a cup (of sugar or flour or almonds or whatever) to measure ingredients in a recipe. Adding or subtracting “stops” of light by increasing or decreasing the shutter speed, f-stop, or ISO makes a scene brighter or darker.
The beauty of metering is that a stop of light is a stop of light is a stop of light, whether you control it with the:
But while an aperture stop adds/subtracts the same amount of light as a shutter speed or ISO stop, the resulting picture can vary significantly based on which exposure variable combination you choose. Your shutter speed choice determines whether motion in the frame is blurred or frozen, while the aperture choice determines the picture’s depth of field. And while an ISO stop also adds/subtracts the same amount of light as shutter speed and aperture without affecting motion and depth, image quality decreases as the ISO increases. So getting the light right is only part of the exposure objective—you also need to consider how you want to handle any motion in the scene, and how much depth of field to capture.
For example, let’s say you’re photographing autumn leaves in a light breeze. You got the exposure right, but the leaves are blurred. To freeze that blur, you halve the time the shutter is open (faster shutter speed) to freeze the motion, but also reducing the light reaching the sensor by one stop. To replace that lost light, you could open your aperture by a stop (change the f-stop), double the ISO, or make a combination of fractional f-stop and ISO adjustments that total one stop. That’s a creative choice your camera isn’t capable of.
Today’s cameras have the ability to measure, or “meter” the light in a scene before the shutter clicks. In fact, most cameras have many different ways of evaluating a scene’s light. Your camera’s metering mode determines the amount of the frame the meter “sees.” The larger the area your meter measures, the greater the potential for a wide range of tones. Since most scenes have a range of tones from dark shadows to bright highlights, the meter will take an average of the tones it finds in its metering zone.
Metering mode options range from “spot” metering a very small part of the scene, to “matrix” (also know as “evaluative”), which looks at the entire scene and actually tries to guess at what it sees. Each camera manufacturer offers a variety of modes and there’s no consensus on name and function (different function for the same name, same function for different names) among manufacturers, so it’s best to read your camera’s manual to familiarize yourself with its metering modes.
Since I want as much control as possible, I prefer spot metering because it’s the most precise, covering the smallest area of the frame possible, an imaginary circle in the center three (or so) percent (depending on the camera) of what’s visible in the viewfinder. Spot metering, I can target the part of the frame I deem most important and base my exposure decision on the reading there.
Spot metering isn’t available in all cameras. In some cameras, the most precise (smallest metering area) metering mode available is “partial,” which covers a little more of the scene, somewhere around ten percent.
Don’t confuse the metering mode with the exposure mode. While the metering mode determines what the meter sees, the exposure mode determines the way the camera handles that information. Most DSLR (digital single lens reflex) and mirrorless cameras offer manual, aperture priority, shutter priority, and a variety of program or automatic exposure modes. Serious landscape photographers usually forego the full automatic/program modes in favor of manual (my preference) or aperture/shutter priority modes that offer more control.
If you select aperture or shutter priority mode, you specify the aperture (f-stop) or shutter speed, and the camera sets the shutter speed or aperture that delivers a middle tone based on what the meter sees. But you’re not done. Unless you really do want the middle tone result the camera desires (possible but far from certain), you then need to adjust the exposure compensation (usually a button with a +/- symbol) to specify the amount you want your subject to be above or below a middle tone.
For example, if you point your spot meter at a bright, sunlit cloud, the camera will only give your picture enough light make the cloud a middle tone—but if you’ve only given your scene enough light to make a white cloud gray, it stands to reason that the rest of your picture will be too dark. To avoid this, you would adjust exposure compensation to instruct your camera to make the cloud brighter than a middle tone by adding two stops of light (or however much light you want to give the cloud to make it whatever tone you think it should be).
Rather than aperture priority, I prefer manual mode because I never want my camera making decisions for me. And once it’s mastered (a simple task), I think manual metering is easier. In manual mode, after setting my aperture (based on the depth of field I want), I point my spot-meter zone (the center 3% of the scene in my viewfinder) at the area I want to meter on and dial in whatever shutter speed gives me the amount of light I think will make that subject (where my meter points) the tone I want. That’s it. (In manual mode you can ignore the exposure compensation button.)
Trust your histogram
I see many people people base exposure decisions on the brightness of the image on the LCD. The typical approach is some variation of: 1) Guess at the exposure settings 2) Click 3) Look at the picture on the LCD 4) Adjust 5) Repeat. Not only is this approach lazy, it’s a waste of time and woefully inaccurate.
I call it lazy because these photographers (but of course I don’t mean you) don’t care enough about their craft to apply a skill that only takes minutes to learn (see above), a skill that will serve them best in the most difficult exposure situations. But that’s not the real problem—the real problem is the inaccuracy introduced by trusting the image on your LCD.
LCDs vary in brightness because viewing conditions change. With a brightness adjustment in every camera’s menu, many photographers simply turn their brightness to maximum because it’s easier to see, especially in sunlight, and a bright picture usually looks better. Other photographers use an auto-brightness setting that adjusts with ambient light—the more light it detects, the brighter the display.
Regardless of your LCD’s brightness setting, the variation in brightness of the screen and/or the ambient light make the image on the LCD a very unreliable exposure indicator. When people tell me their images are usually too dark on their computer or in prints, the first thing I do is check the brightness of their camera’s LCD—if it’s set to maximum, they’re likely fooled into thinking the exposure was brighter than it actually was.
How do you fix this? Simple: Learn to read a histogram, and never use your camera’s LCD for exposure decisions again. The histogram is as simple as it is useful.
One more time
So let’s review. Start by selecting your metering mode (the way your meters”sees” the scene: spot, partial, matrix, and so on), then take your camera out of auto exposure mode and put it in manual (my recommendation) or aperture priority (if you prefer) mode. (Remember, I’m a landscape photographer so I never use shutter priority; if you’re shooting action, to better control the motion in your frame, you probably want to consider shutter priority if you don’t like manual exposure.)
Before metering, set your camera to whatever aperture you decide your composition calls for. Then meter, remembering that your camera isn’t telling you what the exposure should be, it’s telling you the exposure that will make what it sees a middle tone. Finally, correct the meter’s middle-tone bias by dialing in the shutter speed (in manual mode) or exposure compensation (in aperture priority) that gives the correct exposure.
After you click, check your histogram to be sure you got the exposure right.
What’s the correct exposure? That’s a creative choice that’s entirely up to you—feel free to play until you’re comfortable with your results. And the more you do it, the easier it gets.
Below are some sample images and the thought process I followed to get the exposure.
Now get to work
Don’t wait to apply all this for the first time until you really, really want the shot. Instead, find a time when the results don’t matter and play with your camera to find out how much control you have over exposure. In fact, you can do this right now in your backyard or even sitting right there in your recliner. Meter something nearby, set an exposure, and click. Look at the result, adjust the exposure, and click again. Watch your histogram, and watch how its shape shifts right as you increase the exposure, or left as you decrease it. Continue doing this until you’re confident in your ability to make a scene brighter or darker, and can consistently achieve the exposure you expect.
About this image
It not too difficult to figure out how Iceland’s Diamond Beach got its name. A black sand beach on Iceland’s south coast, just down stream from Glacier Lagoon, Diamond Beach is dotted with glistening blocks of ice ranging in size from a refrigerator ice cube, to an entire refrigerator.
As spectacular as Diamond Beach was on my first visit, it was also unlike anything I’d ever seen, so it took me a little while to figure out how I wanted to shoot it. I tried a few frames that used long shutter speeds to blur the motion of the waves around the ice, but when the sun appeared, I saw another opportunity.
With my Sony 12-24 G lens on my Sony a7RIII, I set up just a couple of feet from one of the larger icebergs, went all the way out to 12mm, and waited for the sun to peek above the ice, hoping to capture a sunstar. As I waited, I tweaked my exposure settings, dialing my aperture to f/18 to maximize my depth of field and to enhance the sunstar effect. When the sun appeared I was in business; as it rose, I dropped my camera lower to keep just a small sliver of sun visible above the ice.
Any frame that includes the sun is frame with lots of dynamic range. To get my exposure right for this image, I relied entirely on the histogram and ignored the image on the LCD, with its nearly black shadows and white sky. Despite the way histogram told me I’d captured all the tones, and I confirmed that as soon as I started processing in Lightroom.
Click an image for a closer look, and a slide show.
Posted on February 3, 2019
I’ve seen comets, a meteor storm, fireballs, a total solar eclipse, lots of lunar eclipses, the Milky Way, the Andromeda Galaxy, the Magellanic Clouds, Jupiter’s moons, Saturn’s rings, and many other manifestations of celestial splendor, but I’ve never seen the aurora. So when I scheduled a trip to Iceland this January (the heart of aurora borealis season), ostensibly to scout for the new Iceland photo workshop I’ll be doing with Don Smith next winter, my personal goal was to see the northern lights.
We’d only be in Iceland for one week, long enough for our guide (the expert, energetic, and always entertaining Óli Haukur) to give us a quick view of all the locations we’d visit in next year’s 10-day Iceland workshop (which will also include a local photography guide). With 10:30 a.m. sunrises and 5:00 p.m. sunsets, I didn’t expect the schedule to be too grueling, but I hadn’t accounted for Iceland’s two-hour winter sunrises and sunsets. With many miles to cover beneath a sun that never rises higher than (an extremely photogenic) 8 degrees above the horizon, every minute between our early starts and late dinners was spent spent either driving or photographing (fortunately, the schedule will be a little less compressed during the workshop). But wait, there’s more…. Given our aurora aspirations, each night immediately after dinner, we bundled up and ventured into the frigid dark seeking an electric light show.
For our nightly aurora hunt we’d drive a pretty scene that had both dark skies (not hard to find in Iceland) and a clear view of the northern sky. There we’d sit for an hour or two, fogging the windows in Óli’s spacious Suburban, trading stories and laughs, and periodically stepping into the cold to scan the sky, before ultimately deciding tonight wasn’t going to be the night.
With just two days in Iceland remaining, I was getting a little anxious, but things were looking up (both figuratively and literally). First, Wednesday’s forecast promised completely clear skies, a first for our visit. And Wednesday’s destination was Glacier Lagoon, a magnificent ocean inlet dotted with floating icebergs and a patchwork of thin ice and reflective water that makes an ideal foreground for the northern lights.
The aurora forecast that night was 2 on the 0-9 KP-index of magnetic activity, where 0 is “Enjoy your sleep” and 9 is “Don’t forget the sunglasses” (or something like that), bu Óli assured us that he’s “seen some great shows on ‘2’ and ‘3’ aurora nights,” though I was skeptical because we’d already struck out more than once with a similar forecast. He also told us that his favorite aurora nights are in the 4 and 5 range because with an index higher than that, the aurora can be so intense that an exposure that doesn’t blow the lights is too dark to capture the foreground.
Pulling into the parking lot Wednesday night and turning off the headlights, I immediately spotted a low fog hovering above the lagoon. Except Óli said that wasn’t fog, it was the beginning of the aurora. Dubious, we followed him down to the lagoon. I was thrilled (understatement) when my camera validated Óli’s assertion: My first view of the northern lights!
We spent a couple of hours photographing a low-hanging, fuzzy green bands, with hints of red, that for a few minutes brightened and took on a little definition. On the drive back to the hotel, Don and I could barely contain our elation, while Óli was pleased but relatively subdued. For an Iceland native, this was just another day at the office; for two photographers from California, it was a personal milestone. And then Thursday happened.
All week Óli had told us our best chance for the northern lights would be Thursday, our tour’s final night. We spent that day photographing spots near Glacier Lagoon: sunrise and sunset at Diamond Beach bookending a visit to a glacier ice cave. But as the day progressed, the wind picked up and clouds formed and thickened. We didn’t stress though, because we had our aurora pictures and it was difficult to imagine anything better than what we’d seen on Wednesday.
Nevertheless, despite a 100 percent cloud cover after sunset, we agreed to meet for dinner with camera gear in tow, ready for an optimistic venture back to Glacier Lagoon. And sure enough, emerging from the restaurant we saw the gray blanket had been replaced by ceiling of stars and we were in business. But still no aurora.
Hoping for a little different perspective, we started by scaling a hill overlooking the lagoon, sinking into thigh-high snow and fighting a 40-MPH headwind to summit. That adventure lasted about five minutes before the wind and less than ideal view (you don’t know until you try) drove us back to the site of last night’s success, in retrospect a wise choice indeed.
Back in the lagoon parking lot, we sat and watched a faint aurora ebb and flow, suddenly aurora snobs (“This is nothing like last night”). What looked promising out my north-facing side window one minute, all but disappeared the next, but then we noticed new activity in the western sky out the windshield. This ramped up so fast that we bolted down to the lagoon like Keystone Cops, and by the time I was set up the had become a green and (occasionally) red psychedelic extravaganza.
The next two hours were a blur as I witnessed what was quite possibly the most beautiful thing I’ve ever seen in my life (rivaled only by, and impossible to compare to, the total solar eclipse in August 2017). Starting across the lagoon, in the western sky, the show gradually moved south(defying all my expectations), forcing me to constantly shift further up the lagoon to keep the ice and water in my foreground.
With my head on a swivel, I watched glowing tendrils stretch skyward, some touching both the east and west horizons, others pulsing, spiraling, and doubling back,. It felt like I was inside a giant lava lamp. At one point I tore my eyes from the show above the lagoon and saw the entire eastern sky ablaze with tangled green ribbons. so intense that I turned my back on the lagoon and quickly scaled the snowy hill behind me for a better view in the other direction. Within ten minutes things picked up again over the lagoon and I raced (and occasionally tumbled) back down the hill.
This is the only picture from that night that I’ve processed so far. And while it definitely should give you an idea of what I saw, it’s just a fraction of night’s mesmerizing display. Though the color wasn’t nearly this vivid to the eye, thanks to the camera’s extreme light gathering capability, this is pretty much the way it looked in the viewfinder of my Sony a7SII, and on my LCD preview after capture. About the only significant processing I did was tone down the green reflecting on the snow—not because it wasn’t there, but because I feared that keeping the actual amount of green I captured would strain credibility.
Getting a shot like this requires a significant amount of good fortune for sure, but all the good fortune in the world will do you no good if you don’t bundle up and get yourself into the extreme latitudes in winter. Also helpful is a little experience with night photography, specifically the ability to control your camera, compose, and focus in extremely low light.
While I benefited from an a7SII that can virtually see in the dark (making low light composition and focus a breeze), pretty much any relatively recent DSLR will do the job. Add to that a sturdy tripod and wide (24mm or wider), relatively fast glass (f/2.8 or faster, though I was able to make my Sony 12-24 f/4 lens work when the show was at its peak), and you’ll be fine.
I can’t emphasize too much how important finding a foreground to go with your aurora is. The northern lights are so spectacular, it’s easy to just show and forget to compose the scene. An aurora show like this changes so quickly, intimate local familiarity to know where to be without hunting is a big help. Our guide got us to a location with a wealth of foreground opportunities, but it certainly didn’t hurt that this was my third visit to Glacier Lagoon in two days. And when you get there, make sure you find both horizontal and vertical compositions.
And finally (because I know you’re going to ask), a few words about exposure settings. Keep in my that this was in fact my first rodeo, so you might find better advice elsewhere. But my Thursday shoot did benefit from knowledge gained Wednesday night. Specifically, my moonless night photography had been mostly limited to star trail and Milky Way shoots, where it’s all about maximizing light. But despite the moon’s absence for both of our northern lights shoots (though I’m told the moon isn’t the aurora deal-breaker it is with a Milky Way shoot), the rules are different for an aurora shoot because the sky’s brightness changes by the minute, and it’s often much brighter than a Milky Way sky.
On Wednesday I started with exposure settings closer to my Milky Way settings, using exposure times in the 15-30 second range because it’s virtually impossible to give a Milky Way scene too much light (with 2019 or earlier camera technology). But with an aurora, there is definitely such a thing as too much light.
When my exposure blew out the aurora during the Wednesday shoot, I took the opportunity to drop my ISO and f-stop, thinking that would improve my image quality. But the fingers of color shift so quickly in an active aurora like Thursday’s, a long a shutter duration blurs the display’s definition. On Thursday I tried to keep my shutter speed at 10-seconds or faster (faster is better), which was no problem given the aurora’s brightness.
By now you’ve probably figured out that you need to check your highlight alert and histogram with every frame, and adjust accordingly. And unlike most scenes, the RGB histogram is essential—many times my luminosity histogram (the white one) looked fine, but the RGB histogram’s green channel was seriously clipped.
Oh yeah, and don’t make the rookie mistake I made. Extreme cold like this (it was probably around 20F) will suck the life from a lithium ion battery. But because I’ve grown so accustomed to the great battery life of my Sony a7RIII, I forgot to make sure I’d packed my backup battery. I had one back in the room, which made it about as useful as chocolate frying pan. My battery started at 100%, dropped to 70% in about thirty minutes, and completely died 5 five minutes later. Fortunately Don took mercy on me and loaned me one of his four batteries. On Thursday I was much smarter: not only did I bring my backup battery, I brought an Anker portable charging cube and a charger.
I’m writing this on the plane home from Iceland, about to lose the charge on my laptop, so you’ll need to wait until a future post to learn more about the fascinating science of auroras (because I think it’s important to understand what you photograph). And let me just apologize in advance for the number of aurora images I’ll be sharing over the coming months (I’ll do my best to spread them out some, and I certainly have many other Iceland delights to share).
Click an image for a closer look and slide show. Refresh the window to reorder the display.