Lesson 109 (DSLRs): Lightening and Long Exposure

Since I promised more examples of things you can do with long exposures in Lesson 108 and then we had a storm that offered a great opportunity to shoot lightening, here’s the first follow-up example.

Before we go into how to shoot lightening, let’s start with a little background on the shutter setting I prefer for this.

For lightening shots, I think it’s easiest to use that mysterious shutter speed called “Bulb.”   The first step is to find how to turn it on.  In some cameras, the shooting mode dial on the top of the camera has a “B” for Bulb and turning the dial to B is all you need to do.  In other cameras, “bulb” is at the end of the shutter speed options just past the setting for 30 seconds.  In this case, turn the shooting mode dial to “M” (for Manual) and then set the shutter speed to “Bulb.”

So now you’re in “Bulb” and you may be wondering what the heck that means.  This setting let’s you to open the shutter and keep it open until you decide to close it.  To do this, you either have to hold the shutter button down the entire time you want the shutter opened or you need to use a remote.

I am currently using a Pixel Pro Oppilas wireless remote, which was amazingly cheap.  In fact, I accidentally ordered 2 and decided for the $20 price tag, it was worth keeping the second one as a backup.

In any case, whether you choose a cheap 3rd party wireless remote, a wired remote, or a high-end wireless remote, you will definitely want a remote for bulb exposures.  There are two reasons for this:  1)  It’s very annoying to have to stand around holding the shutter button down for extensive periods of time, and 2) It’s extremely difficult to hold the shutter button down without introducing camera shake, which will cause blur in your images.

So, you’re in bulb mode and you have a remote attached to your camera.  You will also need to put your camera on a tripod.  This is a must.  And a solid tripod that won’t allow your camera to vibrate helps tremendously.  Alternatively, you need a really solid place to set your camera.  A fellow photographer friend says setting the camera on a large bean bag will help keep it stable if you have a flat surface to put it on.

Next, you need a safe vantage point to shoot from.  A safe vantage point is not, for example, the middle of an open field, under the one tree in said open field, on a roof top, or anywhere above timberline on a mountain.  A safe vantage point generally means that you are indoors.  Some folks shoot lightening through car or home windows using a polarizing filter to remove glare from the glass.  This is definitely the safest thing to do.  For recommendations on lightening and safety, go here:  http://www.lightningsafety.com/nlsi_pls.html

I will make no recommendations and I am not going to tell you where I shoot from because I don’t want to be responsible for anyone besides myself when it comes to lightening safety.  🙂

That said, let’s assume you’ve found a good, safe place to shoot lightening from.  Now that you’ve found your place, you next need to be there at the right time.

Since night time lightening is more dramatic, if you are at home in the evening, having a spot you can get to on a moment’s notice increases the odds that you will be able to capture some great shots.  Otherwise, watch the weather forecast and be prepared to go to your favorite location only to be disappointed.

Let’s say all has aligned and now you have your camera in Bulb, with a remote, on a tripod, in a safe location, and there is lightening!  You are 90% of the way there!

There are lots of different opinions on what to do next.  This is my personal preference:

  1. Use the widest focal length you’ve got.  It greatly increases the odds that lightening will be captured inside the frame since you cannot predict where it will strike.  The examples for this post were shot at 16mm on a camera with a full frame sensor (meaning 40% wider than if you’re using a crop-sensor camera).  Images were then cropped in post-processing.
  2. I use one of two options for focusing.  If there is enough light to focus either automatically or manually, I like to focus on an object in the landscape that will result in getting everything in the frame sharp.  I like to include foreground objects (like buildings) for scale.  If it is too dark to find focus, I set my lens to manual focus and then turn the focusing ring until the mark aligns with the infinity symbol (this is called focusing at infinity).  If everything in the frame is at the hyperfocal distance or further from the camera, this will keep everything sharp as well.  (If you don’t know what hyperfocal distance is, it just means from that point on, everything to infinity will be acceptably sharp.  You can use a Depth of Field calculator to get an estimate of this distance.  See Lesson 106 for more info on calculating this.)
  3. Stop down the aperture to something around f/16ish.  I like f/16 because it gives me so much depth of field that I don’t have to worry about everything being sharp and, more importantly, allows for very long exposure times without overexposing the image between lightening strikes.  That said, when you are shooting with a very wide angle focal length and your subject is far away, you don’t need to be on f/16 to get a lot of DOF, so feel free to try opening up the aperture if you find that works better for you.
  4. Set the ISO as low as you can.  I started with ISO 400, over exposed a strike that was very close, turned it down to 100, under exposed several strikes that were further away, and then turned it up to 200.  This is not an exact science, but be aware that long exposures, especially at night, tend to get very noisy (speckled and grainy).  Setting a high ISO will also add noise, but decreases the length of time the shutter needs to stay open.  In this case, what we’re trying to do is keep the shutter open as long as possible with the least exposure until lightening actually strikes.  So, we really want just enough light amplification (what the ISO setting controls) to allow for a great exposure during the lightening strike.
  5. Get your camera all set and pointed at the sky (don’t forget to level it) and then take a comfortable seat.
  6. Some people claim they can sense lightening before it strikes.  I suggest that if you find your arm hairs standing on end or have some sense of an electrical charge, it’s time to move–quickly!  I open the shutter with my remote and watch and listen.
  7. I leave my shutter open for a while and watch how many flashes there are in the sky and how bright they are.  If they are not very bright, I will wait through several flashes and then close the shutter (by pressing the remote shutter release a second time). 
  8. This next step is critical:  look at the exposure you got.  I do not have a scientific way to predict what exposure you will need for lightening.  This is very much a feel thing.  The longer you sit there watching the storm, guessing at how much light has reached your sensor and checking to see if you guessed right, the better you will get at this.  The important thing to bear in mind is that when lightening strikes, if it’s very bright, it’s time to close the shutter and start the next exposure.  Conversely, if you’ve been getting lots of flashes in the clouds but no bright strikes and you’ve had the shutter open for a while, it’s probably time to close the shutter and start over.  If the sky gets too exposed before the lightening strikes, the lightening will not show up as well.

One word of caution:  leaving your shutter open for extensive periods of time will drain your battery quickly.  Make sure you have a fully charged battery (and a spare if you have it).

In a nutshell, my approach to get lightening shots is to have the right equipment, show up in the right place at the right time, get ready, and then open my shutter and adjust as things happen.  Kind of like life.  🙂

Lesson 108 (All Cameras): Long Exposures

Note for iPhoneographers: the SlowShutter app will allow you apply this information to the iPhone, although stabilizing the iPhone (even in an iPhone tripod) can be challenging.  See Lesson 101.

When I teach beginning photography workshops, one of the things I spend a lot of time working with students on is the relationship between exposure and artistic expression.  Shutter speed is one of the big ways in which we control both exposure and motion showing in our images.

Slow shutter speeds leave the shutter open for longer periods of time, allowing more light to reach our sensors for exposure.  They also allow any motion in the subject to blur.  Most of us strive for tack sharp images, so why would we ever use long shutter speeds?

First, sometimes you have to use a slow (long) shutter speed if you’re shooting in low-light conditions.  Second, allowing motion to blur can create some cool artistic effects.  And third, if you need lots of depth of field, you’re going to need a small aperture.  The age-old analogy for the relationship between the shutter speed and the aperture size is to think of a water faucet.  How long you turn the water on is like your shutter speed.  How wide you open the valve is like your aperture.  If you turn a water faucet on wide open for a split second, you can get the same amount of water as if you turn the water on at a trickle but let it run for a much longer time.  That’s how aperture and shutter speed work together to control the total volume of light that will reach your sensor and why using a small aperture usually means a slower shutter.

Let’s start with an example that was both low-light and a small aperture, but with no motion:

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This example was shot at twilight with a 1 second exposure at f/18.  F/18 is a small aperture opening and 1 second is a slow shutter speed.  By using a tripod and a 2-second delay on the shooting mode, I was able to keep the camera still and avoid introducing motion blur.  I got the exposure I wanted and kept everything from the rail in the foreground to the building in the background sharp.

Now let’s take a look at what happens if you don’t keep your camera still:

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In this example, I literally picked up my camera/tripod and moved it in about the last second of a 25 second exposure.  Because the building in the background is so much dimmer than the lights going up the path, the building did not blur while the lights, being so bright, created trails across the image.

Now let’s talk about using long shutter speeds to show motion in the subject itself.  Waterfalls are a popular subject for this technique.  By putting the camera on a tripod again, everything in the image that is still remains sharp but the moving water blurs to a soft “flow” through the image, visually communicating the movement of the water.

Compare this image (shot at ⅙ of a second) to the one after it (shot at 1/320 of a second):

The fast (1/320) shutter speed freezes the splashes of water while the slower shutter speed (⅙) allows the water to blur into softness.  Which one you prefer is a matter of taste (in this case, I like the faster shutter speed better, but that’s partly because it’s slightly less exposed and has less flare from the sun).

Now let’s look at an example of low-light, moving water, and lots of depth of field:

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This was a 20 second exposure shot at f/16.  The small aperture not only provides more depth of field, but it also turns the lights on the bridge into stars.  The slow shutter allows the water coming out of the water cannons to blur into soft streams.  Also notice the surface of the river–the splashes and ripples have also smoothed out into soft lines.

There are many more fun things you can do with a long exposure, but I’ll save those for future posts.  🙂

Lesson 107: Depth of Field Through the Lens

I taught a Beginners class on macro and close-up photography on Saturday.  Macro teaches us a lot of great skills as photographers.  Because shooting subjects life-sized or bigger magnifies the mistakes we might get away with if our subjects didn’t loom so large on our sensors, macro serves to remind us and help really bring home some basic photography concepts in a whole new way.

Depth of Field is of primary concern with macro photography.  When you’re shooting practically on top of your subject, DOF is reduced to fractions of an inch–sometimes DOF is so tiny that it’s easier to think of it in millimeters, even for metric-adverse Americans.

One of the things that often confuses beginning (and even more experienced) photographers is that the depth of field you see when you look through the lens is not the depth of field you’ll get when you create the image (unless you happen to be shooting with your aperture wide open).

For example, during class, I was shooting with the Canon 100mm f/2.8L IS macro lens.  When I looked through the lens at a dandelion, this is what I saw:

The inside of the dandelion (f/2.8)
The inside of the dandelion (f/2.8)

Pretty cool, huh?  When you are looking through the lens, the aperture is wide open regardless of what aperture setting you have selected for exposure.  This allows the maximum light through the lens for you to see as well as for functions like autofocus to work better. 

Some cameras have a DOF preview button that stops the aperture down to what you’ve set it at so you can theoretically tell how much DOF you’re actually going to get.  I find this button to be only marginally useful.  I rarely can tell how much DOF I’m getting by pressing it, partly because of the loss of light.

Instead, I tend to take a shot and use a magnifying loupe to look at it on the LCD.  I may also zoom into the image to enlarge it for more careful viewing.  Then I decide if I like the DOF I’m getting and adjust if not.

In the next example, I shot the same dandelion at f/16 instead of f/2.8 (as in the first example).  Notice how we see the full ball of fluff instead of getting a horizontal view of the inside of the dandelion seeds?  That’s because there is enough DOF for the foreground portion of the seed ball to not blur completely out of view.

Same Dandelion at f/16
Same Dandelion at f/16

Personally, I find the very shallow depth of field more interesting in this case–it’s like having a view of the inside of the flower.  However, if I wanted a shot of dandelion that looked more like what we see in life, the second example would be my pick.  In fact, I’d probably want a little more depth of field to keep the tufts of the closest seen “fronds” sharp.