What classifies as a 'long exposure' anyway?
Well, that depends a lot on your subject; however, it is typically seen as around a full second or longer. As far as the history of photography, this is not a new concept. In fact, a huge hurdle in the development of practical 'cameras' was the fact that early designs required hours to expose! The first portrait studios used Daguerreotypes, which they had managed to reduce to a mere 15-30 minutes to expose. By 1842, that was dropped to a lightning fast 10 to 60 seconds... Keep in mind, exposures of that amount of time (even on the shorter end) tend to blur anything that moves. This is often the desired effect, but for portrait photographers it creates a huge problem. People cannot physically hold still for that long, so they would end up with blurry photographs. No one wants to pay for blurry photographs. For those early photographers, this was often solved by using something like this:
|Always try to make your client as comfortable as possible. (Image credit)|
1. A Tripod. It is essential that you invest in a good, sturdy tripod. I guess you can try to set your camera on a rock - I've done this more times than I care to admit - but that usually doesn't turn out well.
2. Remote Trigger, Shutter Release Cable, or Intervalometer. This is simply something that will fire your camera shutter without you having to press the button. During long exposures, simply releasing the shutter with your finger creates enough vibration to blur your image when viewed closely. In fact, even the mirror moving out from in front of the shutter and sensor can do this, but more on that later.
3. Neutral Density Filter(s). This type of filter is simply a piece of glass or plastic that is darkened, so that when placed in front of a lens, a longer exposure can be achieved. As with any filter, do your research and invest in a good one. Some will create certain color casts that may be unwanted, or lower the sharpness of that lens you just spent so much money on. Neutral Density Filters come in many varieties. Graduated filters offer one side clear, and one side dark - useful for sunsets - and a transition (hard or soft) between the two. This item isn't actually required, as some of this we'll talk about shooting at night. During the day, you'll certainly want one.
4. Patience. Maybe bring a book with you.
This image of Multnomah Falls in Oregon was shot in the mid-morning hours in the shade with an exposure of 3 minutes. I also used a 6-stop neutral density filter.
|A 10" exposure from the hike to Timpanogos|
So, you've found your waterfall, it's in the shade, filter on. Get your tripod set: avoid putting the legs in the moving water of the river, or movement from the water will blur things in unwanted ways. Set tripod legs up on rocks or solid dirt that won't shift or let the feet sink in. Next, set your focus and switch your lens to manual focus, to ensure it doesn't try to refocus when you release the shutter. Now, if your exposure needs to be 30 seconds or less, you're good to go. Otherwise, get the calculator out (phones have these).
You'll need to know a bit about manual exposures for this part. Since your camera wont dial to anything more than 30 seconds, we're using Bulb. Some cameras have their own place on the Mode Dial for this (B, as seen to the right), others just have it as a shutter speed option (scroll past 30"). This mode will hold the shutter open for as long as the button or cable release is pressed. If you have a wireless remote, they typically work by one press opening the shutter and the next press closing the shutter. To calculate the length of time we need to expose the sensor, first set your shutter speed to 30 seconds. Now find an aperture that would grant you a perfect image with these settings if you can't go wide enough with the aperture, bring the ISO up as far as needed - it's just to meter with. I like to use spot metering and read the highlights of the white in the waterfall: I know this point needs to be at least +2 or higher on the light meter to show bright enough in the image. Go ahead and take a test shot to be sure. Got a good exposure? Perfect. Now bring your ISO back to it's lowest native setting (usually 100 or 200) and drop that aperture as far as you can (Note: some people argue that f/16 or f/22 is the smallest you should go as anything lower, like f/32 or even f/22, will start to show any lens defects or dust on a lens and sensor more prominently). How far did you have to go to get to your desired setting? For every stop of light you adjusted, double you're shutter speed. For example:
If you moved from f/8 to f/22 that's 3 stops (f/8 > f/11 > f/16 > f/22). So we would need to shoot for 4 minutes (30" > 1m > 2m > 4m)
That was too easy, here's another:
If you maxed out your aperture at f/5.6 and had to move the ISO up to 500 and you need to go to f/22 and 200 ISO:
f/5.6 > f/8 > f/11 > f/16 > f/22 = 4 stops +
500 > 250 > 200 (curveball) = 1 1/3 stops for a total of 5 1/3 stops, so:
30" > 1m > 2m > 4m > 8m >16m = 16m +1/3 which means 21 minutes, 20 seconds (16*1.33 = 21.33)
Remember asking your math teacher "when will I ever use this?"
Set your phone's stopwatch to 21' 20" and get out that book. Or, if you have an intervalometer, just program the time and it will close the shutter when it's done.
If you don't have a release cable - or you left it in the car, like me - use the camera's self-timer mode to avoid movement from your finger pressing the button. Bulb mode doesn't work as well without a cable release, but throw some gaffers or electrical tape in your bag. It is possible to tape a small, smooth pebble over the shutter button. Used with the 10 second timer, you just may be able to buy yourself enough time to get it taped down. Or, put something dark and opaque over the lens (a jacket or backpack's rain cover), tape the shutter, and start the timer when you move the jacket (being extra careful not to touch the focus ring, of course). Replace when the time is up and you buy yourself some time to get the pebble back off the shutter. I don't particularly recommend this method, but hey, when you're as forgetful as I am, sometimes you need to improvise.
If your camera has a mirror lock-up mode, I would use that as well. Lock-up raises the camera's mirror before actually starting the exposure - Thus, eliminating extra vibrations there as well. If you don't see mirror lockup in the menu try live-view. Most cameras have this option now and it works by feeding you the image directly via the camera sensor, therefore, the mirror must be locked up for live-view to function. If your camera has an electronic viewfinder, it may not have a mirror.
Long exposures work great for water in other forms, too. Rivers, oceans, or lakes can be smoothed to look perfectly calm and produce a nice reflection like in the 7 minute exposure below. Also notice how the clouds take on that similar, silky smooth appearance.
|Portland, Oregon skyline from the Eastbank Promenade|
Here's a shot from the Washington Coast, illustrating how even rough waters of the ocean can be given a smooth, cloudy, dreamlike appearance.
|25 seconds of waves washing over rocks and sea stars on Ruby Beach|
|Pan with your subject to isolate them.|
Okay, so 21 minutes might be a bit long for a waterfall. But it's really not that long if you're planning to shoot some star trails, or maybe do some serious light painting.
Lets talk Star Trails.
A hugely-popular and equally frustrating topic for many photographers. This one is going to take some practice.
|Uranium mine ruins under Temple Mountain|
Set up your tripod and get your focus. This is one of the most difficult parts of shooting in the dark. Use a flashlight or headlamp to light up the foreground and focus there. Walk over and place a light on/near your foreground subject if it's further away. Shining the light toward the camera or at a subject from close up should be enough to get a focus on it. Use live-view and the digital zoom for easier manual focusing, as auto focus may not work at all in this situation. With any luck there may be a car or campfire in the distance you can focus on. Look all around you, you can focus on something that's not in your shot at a distance close to what you need. I avoid trying to use the lens' focus distance markings as I rarely find them very accurate, especially the 'infinite' distance setting. Technically, this should show everything past its maximum focus distance to be sharp. Not usually (ever?) the case. Take the extra time to get it perfect.
As far as your exposure, you want to limit the amount of digital noise, while maximizing the light from the stars. 100 ISO and a maximum aperture is key (2.8 if you can, or as wide as your lens can go). I typically keep my camera's noise reduction to the lower settings, as I've found that Lightroom/Photoshop do a much better job of reducing noise after-the-fact than what a camera can do. Because, guess what? Your camera is doing the same thing any post-process program will do to reduce noise, but with a much smaller computer controlling it. It also eats up what is otherwise valuable shooting/sleeping time.
As far as shutter speeds go, there are a couple of routes you can take here.
|96 minutes over the Spiral Jetty|
dare given your cameras battery life. If the battery dies before the timer runs out, no photo for you! No worries about calculating shutter times, so long as the skies and your surroundings are truly dark. If they aren't, use the process I showed in the waterfall scenario. You will definitely need a calculator for this one, as it usually looks something like this:
Test Shot at 6400 ISO for 2 minutes; reducing to 100 ISO = 6 stops, or 128 minutes.
As seen in the shot of the Miners' huts in the image above, light from the rising moon limited the length of time the shutter could be open before the skies started to wash out with noise.
If you have dark enough skies you may as well run it for a few hours, if you think the batteries will hold. Note: when it's cold outside (like at night) batteries won't last nearly as long as when they stay warm.
Route 2. Photo Stacking. A little more advanced, and you'll need Photoshop and some basic Photoshop skills for this one. Don't worry, it's nothing YouTube can't teach you if you have the desire.
Photo stacking is a new trend arising with new technology and advancement of photo editing software. Stacking star trails is an easy way to reduce noise and eliminate unwanted objects wandering through your scene (e.g. airplanes, kids with glow-sticks, UFO's, etc.). Shooting wise, all you need to do is set your camera's shutter to 30 seconds and fire away. All night. Now instead of one file, you have hundreds. Drop them into Photoshop as layers, change them all to 'Screen' mode instead of Normal, and the stars will shine through from all the layers. You'll probably want to learn how to set up an action to run a loop for you. I don't think you want to change 400 layers manually. Afterwards, it's as simple as locating which layers contain unwanted objects, and editing those individually before compressing the layers into one file. Screening layers allows only highlights to pass through, so bear in mind anything with any amount of light will show up. That includes noise, so run your noise reduction before moving them into Photoshop as one very huge file. Also, limit time between shots to less than a second, or you may start to see gaps between your shots in the stars, looking like dotted lines running circles through your photo.
Below is the result of about 4 hours worth of 30 second exposures, combined using the stacking method. The main source of light across the bottom are several trains passing through Gore Canyon over the Colorado River
|Trains run all night through Gore Canyon, Colorado|
Next up, a quick bit about the increasingly popular photo process called light painting.
This is a fun one!
The possibilities are literally endless, and on the technical side, it's really easy to set up. Again, you'll most likely want to limit noise by using the lowest possible ISO setting, and open up your aperture to catch as much light as possible. Other than that, you can shoot as long or as short of shutter speeds as you like. Get out your external flash, put on your headlamp, and throw some glow-sticks around.
Light painting is fun for the whole family!
|Glow-sticks at a family reunion in Capitol Reef|
Combine a light-painting scene with some star trails and really wow your friends. Or, for an added challenge, try illuminating entire landscapes by hand. For this shot I, and three friends, ran around like mad through Goblin Valley with flashes, lanterns and headlamps to light up a field of goblins and a peak about 1/2 mile away from the camera. The finished product was a single image, the exposure just over 13 minutes. There are only four people in this photo.
|Light painting the Goblins in Goblin Valley State Park|
You can also use this technique and let the traffic of the city do the light painting for you. In this shot, the vehicles traveling on the I5 and I90 freeways in Seattle are exposed for two minutes. It's too dark to see any of the vehicles, but their headlights and taillights illuminate the paths they traveled during the time the shutter was open.
|Seattle Traffic merging between I5 and I90|
For more examples of what you can do, check out my new Photos After Dark compilation. All that's left to do is get out there and practice!
Be sure to post your questions in the comments, and feel free to share your long exposure images there as well!
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