Dance Photography (Steps 5-9)

• 1/60 second for a subject posing motionless
• 1/125 second for a subject standing still but swaying
• 1/250 second for a subject walking
• 1/500 second (or faster) for fast movements (running, jumping)

1/60 sec	1/125 sec	1/250 sec

At 1/60, you can see severe motion blur in the dancers at the left who are bowing and slight blur in the dancer who is standing still but raising her arms (click through to see a larger version). At 1/125 there is blur in the hands, right leg and face of the running dancer (but not in the planted left foot). At 1/250 there is blur in the dancer who has just landed a jump. You can see it in the closeup crops below: the face has motion blur (because the whole body is still moving downwards) but the right foot is very sharp (because its motion has been stopped by the floor):

Crop of 1/250 sec (motion blur)	Crop of 1/250 sec (sharp)

Now let's see some photos where motion blur is not a problem:

Motionless pose at 1/125	Crop of Motionless at 1/125	Fast Motion at 1/400

Jump at 1/500	Crop of Jump at 1/500	Another Crop of Jump at 1/500

What can you can do to minimize subject motion blur?

• Choose a fast enough shutter speed (assuming there is enough light to do so). Use the guidelines above, but note that even 1/500 will not freeze all motion; for example in "Another Crop of Jump at 1/500" above, you can see motion blur in the rear shoe.
• Zoom out: when you zoom in you magnify everything, including motion blur. By zooming out and showing the whole stage, motion blur will be less noticeable.
• Shoot when the action has paused: At the end of a movement, or at the top of a jump, the dancer is still. Wait for that moment. In "Jump at 1/500" above, the picture was snapped just at the top of the leap. This not only makes the jump seem more impressive, it also means there is less motion (and thus less motion blur) because at the top the dancer is neither moving up nor down. In "Jump at 1/125" below, the picture was timed at the top of the dancer on the right's jump; we see in the crop she is very sharp. But other dancers who are not at the top of their jump have significant motion blur (as you would expect at 1/125).

Jump at 1/125	Crop (top of jump; sharp)	Crop (bottom of jump; blur)

• Pan with the motion: Move the camera to track the dancer's movements. The dancer will not be blurred (but the background will be). By panning the camera with the Prince as he lifts Clara in the "Pan at 1/40" image below, we handle the very low light in this scene with a shutter speed of 1/40--about six times slower than we would normally need without the pan. Clara has motion blur because she is twisting more quickly than the Prince (and the camera) are moving. You can tell that this shot is a pan because of the Christmas tree lights--they are elongated horizontal lines, not round points of light, indicating that the camera has moved horizontally.

Pan at 1/40	Crop of pan at 1/40	Crop of pan at 1/40

• Try, try again: Suppose you can only get to a shutter speed of 1/60, you want a sharp picture of a moving dancer's face, and you don't care about blur of the arms and legs. If you take just one shot, chances are the face will have motion blur. But if you take 20 shots, chances are that at least one will happen to have caught a moment when the face is motionless and thus sharp.
• Use flash: In my daughter's dance studio, flash photography is not allowed, so I won't cover it. If it is allowed in yours, by all means use it. Check out Strobist or PhotoNotes or photography on the net for some great advice.

• Image stabilization: Buy a lens (or camera) that automatically compensates for small camera motions. Some Canon lenses feature "image stabilization," while Nikon lenses call it "vibration reduction," and Sony builds "SteadyShot" into the camera, not the lens.
• Take a burst of shots. Hold down the shutter and take several shots while keeping the camera still. Even if you make some camera movements, probably one of the images will be taken in between the movements. Keep that one and discard the others. (This technique is sometimes called "poor (wo)man's image stabilization.")
• Roll your finger over the shutter button, don't stab it. Your finger should be resting on the shutter button at all times (and half-pressing to acquire focus before the shot); now gently roll it to take the shot.
• Shoot betwen breaths because breathing in and out moves your body.
• A tripod or monopod is the most stable support--tripod most stable, but monopod more portable. Needless to say, equipment like this can be disruptive to an audience, so save the tripod for a dress rehearsal, not an actual performance.
• Solid hand-holding technique is diagramed below. Keep your elbows tucked in to the body to offer more solid support, with your right hand gripping the camera, your left hand curled under the lens, and the back of the camera pressed against your face. That gives you three points of support, like a tripod. (Moose Peterson suggests a rubber eyecup as a bigger target to lean your face against.)

Hand-held: tucked in

Monopod

Tripod

As a rough rule, you can expect to hand-hold a lens without noticeable shake at a shutter speed at least as fast as the reciprocal of the focal length. For example, with a 200mm lens, this rule says you should be shooting at 1/200 sec or faster. If you have an APS-C (half-frame) camera and/or if you expect to crop the image, this will make the image relatively larger, thus multiplying the effects of shake. To be safe, the rule says to double that figure to 1/400 sec. On the other hand, image stabilization in the lens coupled with good technique (as outlined above) can allow you to shoot about three stops slower (1/50 sec.), sometimes slower still. In the end, for dance photography, if you have image-stabilization and good technique you are more likely to suffer from motion blur than from camera shake.

If the subject does stay still, with good hand-held technique you can shoot at very slow shutter speeds (click through to see the detail):

1/15 sec at 200mm	1/10 sec at 200mm	1/4 sec at 135mm

7: Plane of Focus and Depth of Field

Focus is an artistic decision; it is usually bad to have the main subject out of focus, but it can also be bad to have too much distracting background in focus.

The first thing you have to be aware of is the width of the focal plane--how much of your picture will be in focus. This is called the depth of field, and it depends on four things: the distance to your subject, your aperture setting, the focal length of the lens, and your degree of fussiness or scrutiny. The chart below left shows some sample depths of field for different combinations of distance, aperture, and focal length (with average scrutiny). On the right is a table of the three factors, and a diagram where the focal plane is centered on the middle butterfly, and everything within the depth of field is in focus, while the near and far butterflies are outside the depth of field and are out of focus.

Distance Aperture 50 mm 100 mm 200 mm 20 ft f/2 3'8" 0'11" 0'3" 20 ft f/2.8 5'3" 1'3" 0'4" 20 ft f/4 7'7" 1'10" 0'5" 20 ft f/5.6 11'2" 2'7" 0'8" Distance Aperture 50 mm 100 mm 200 mm 40 ft f/2 15'3" 3'8" 0'11" 40 ft f/2.8 22'5" 5'3" 1'3" 40 ft f/4 34'2" 7'5" 1'10" 40 ft f/5.6 57'5" 10'7" 2'7"

Factor Narrower DOF (more background blur) Deeper DOF (more in focus) Subject to camera distance Closer distance Longer distance Aperture setting Large opening (f/2.8) Small opening (f/11) Lens focal length Telephoto lens (200mm) Wide lens (24mm) Scrutiny Magnifying glass From across room

For example, if you have a 200mm lens set at f/2.8 and you sit 20 feet from the front of the stage, then your depth of field is just 4 inches for a dancer all the way downstage, and 1 foot 3 inches for a dancer 40 feet away upstage.

What does this all mean? It means you have to be careful with the 200mm portraits, but needn't worry much about the 50mm shots. By careful, I mean taking care with where you place the focus selector point (the little dot or rectangle in the viewfinder--on most cameras it lights up red). Suppose you want a portrait of a downstage dancer who is in a pose with her head leaning backwards. If the focus point is somewhere on her torso, then her face will not be in sharp focus. What can you do? You could change your aperture to f/5.6 (or maybe even f/8), giving you more depth of field. Or you could zoom out to 100mm, in which case the depth of field is about 2 feet 7 inches and you'll be fine although you get a wide shot, not a portrait. (I should note at this point that a wide angle lens only gives you more depth of field if you consider the whole shot. If you crop the 24mm shot so that a dancer occupies the same portion of the frame compared to a 200mm shot, then the 24mm and 200mm will have the same depth of field. See, for example, Michael Reichmann's explanation of this.)

But the best solution is to place the focus point exactly where you want it. Your camera has a controller (dial/buttons/joystick) that allows you to select one of several focus points. The image below replicates the view through the viewfinder. I used the joystick to select the top focus point (the red rectangle) and placed it over the dancer's eye while half-pressing the shutter. I waited for a pause in her motion (because this scene is rather dark and I only had a shutter speed of 1/125 sec) and then fully-pressed the shutter to capture this shot.

Focus point on eye (f/2.8, 1/125, ISO 1600, 200mm, distance about 20 feet)

You can see that the depth of field is shallow: the dancers in the background are very blurred, and even the main subject's fingernails, which are only about a foot in front of the focal plane, are somewhat blurred. If I had left the focus point on the default center position (which you can see is on the side of the neck), I would not have gotten the face in sharp focus.

Here are some reasons why the autofocus system can miss, and things you can do to minimize the problems:

• Insufficient time to acquire focus: in continuous autofocus mode the camera focuses when you half-press the shutter and takes the picture as soon as you fully press. If you haven't pre-focused with a half-press, the lens elements won't have time to move to the correct focus point. Make sure you half-press before you take each shot.
• Low contrast: The autofocus system of an SLR works by comparing the light coming from two paths through the lens, trying to make both paths converge on the sensor (and thus be in focus). (If you really want to know the gory details of how it works, you can play with an applet and read an article.) But if you try to focus on an area without any contrasting lines or edges, the autofocus system will have nothing to go on. Eyes are good points of focus both because you especially want them to be sharp, and because they offer good contrasting lines. If you're not focusing on the eyes, do focus on something with texture or edges--for example in the photo above, focus on the sequins would be good; but on the pure white outfit, not so good.
• Subject moved from focus point: sometimes you think you have the focus point right on the dancer's eye, but she makes a sudden movement to duck out of the way and you end up focusing on something behind. Or an arm moves in front and the camera focuses on that. Inevitably you will miss some shots like this; shoot some more! One thing that helps is to keep your other eye open--if your right eye is in the viewfinder, use the left eye to check if someone else is about to move into the frame (or if there is better action somewhere else on the stage).
• Wrong focus point: Sometimes you forget which focus point you have selected and fail to put the right point in the right place. Or if you allow the camera to automatically choose the focus point, it will often choose wrong (so I don't recommend doing that).
• Faulty lens/camera: if you believe the Internet, you'd think that the majority of all lenses sold are horribly defective, focus inaccurately, and must be shipped back to the manufacturer immediately. That hasn't been my experience--when my pictures are out of focus, 100% of the time it is my own damn fault, not the lens. But it is remotely possible that your lens (or your lens/camera combination) is out of alignment and needs to be calibrated. You can bring your equipment in for service or with many recent cameras you can do it yourself.

• Manual Autofocus Point Selection, where you select the focus point with a controller. (Some of the cheapest entry-level cameras make you press two buttons to move the focus point. I would avoid those models.) This is set through the camera's menu system, but you only need to set it once.
• Continuous Autofocus Mode, where the camera continuously updates the focus plane to respond to the dancer's movement, as long as you have the shutter half-pressed. If you take a burst of shots the camera even predicts where the dancer will move to next and places the focal plane there. This mode is set in Nikon cameras with a switch on the front of the camera, near the lens, which should be set to "C" for "Continuous." In Canon cameras, select "AI Servo" mode on either the top panel (with the "AF" button) or the rear-panel quick settings screen. (The alternative mode, single-shot autofocus, is good for static subjects but not so much for movement.)
• Continuous Shooting Mode (not to be confused with continuous autofocus mode), in which the camera takes a burst of pictures as long as you keep holding down the shutter. I use continuous shooting mode because I occasionaly want a burst of several pictures at the height of the action, but 95% of my photos are actually taken in a continuous burst of exactly one frame. Canon calls this the "DRIVE" mode and Nikon calls it the "Advance" mode (as in, how the cartridge of film is advanced); both put it on the top panel.
• Shutter-activated autofocus, in which autofocus is started by a half-press of the shutter button. You may not know that there is an alternative, called back-button focus, in which a button labeled "AF-ON" on the back of the camera activates autofocus, and the shutter button is used only to take the picture. Many sports and action photographers use this option (especially with a big telephoto lens on a tripod), so use it if it works for you; personally I found it made my thumb tired. (Maybe I need some finger aerobics.) I did however set up my camera so that the AF-ON button turns autofocus off. Why? One reason is to focus-and-recompose when I want the focus point to be outside the selectable range. Another reason would be that I focus on a dancer in the back row and then hit the button to turn autofocus off; then if a limb of one of the dancers in front happens to get in the way it won't move the focus plane. I don't use this much for dance, but I do use it often when there are branches or grass in front of wildlife.

Consider the "Focus point on eye" image above. It was taken at f/2.8, 1/125 sec, ISO 1600 and is well-exposed. As we will see in the next section, If we took it at f/11, 1/500 sec we would have to use ISO 102,400. Some cameras go that high, but the results will be extremely noisy. So we have a never-ending trade-off between noise, motion blur, and depth of field. Sometimes there is plenty of light and you have nothing to worry about; sometimes a scene is dark and you must decide which factor to compromise on.

Why are ISO 102,400 pictures noisy? And what is ISO, anyways? ISO is the Internatinal Organization for Standardization, and in 1979 they set up a scale to standardize film speeds; that scale has been transfered over to digital. You can think of ISO 100 as the base rate, and every doubling of the ISO number (to ISO 200, ISO 400, ISO 800, etc.) as telling the camera to count each photon of light twice. So in a perfect world, a photo of a still subject at 1/500 sec at ISO 400 would look the same as a photo at 1/125 sec at ISO 100 (the former is 1/4 the time and counts each photon 4 times). But we don't live in a perfect world; we live in a random quantum world in which there is always fluctuation in the amount of light gathered. At ISO 102,400 each little fluctuation is magnified by a factor of 1024, making them very visible.

With my full-frame Canon 5D II camera, I'm confident starting out at ISO 1600, but if the light changes to a brighter scene I take advantage of it and switch the ISO to 1250, 1000, or even 800. In dimly-lit scenes I will switch to 2000, and very reluctantly to ISO 3200 and above. Here are some examples--they look pretty good even with the crops, but if you click through to the even-larger versions, you can see noise in the 3200 and 5000 shots.

ISO 1600	ISO 3200	ISO 5000
Crop of ISO 1600	Crop of ISO 3200	Crop of ISO 5000

The thing that bothers me most about my camera is that I need a two-touch sequence to change ISO: press a button and then turn a dial. I wish there were a dedicated dial so that I could more easily change ISO to match the brightness of the scene.

Another option is auto-ISO. I haven't used this much because I find it guesses wrong too often, but maybe I'm not using it right (and maybe newer cameras or other manufacturers implement it better), so you could consider trying it.

The web site DxOMark tests cameras and reports the highest ISO speed at which cameras continue to deliver excellent picture quality. Here are some of their ratings, to which I've added the sensor area and approximate price:

Highest Excellent ISO	Camera	Sensor Area	Price
2300	Nikon D700	full-frame	$2600
1800	Canon 5D II	full-frame	$2600
1200	Nikon D5100 / D7000	half-frame	$900
1150	Pentax K5	half-frame	$1300
1100	Sony Alpha 580	half-frame	$900
900	Nikon D3100	half-frame	$700
850	Canon 7D	half-frame	$1300
800	Canon T2i / T3 / T3i / 60D	half-frame	$600-$900
550	Nikon D3000	half-frame	$500
550	Olympus EPL2 / E510	quarter	$600

You can see that the larger the sensor area, the better the performance. You probably can't notice the noise difference between the Nikon D7000 (ISO 1200) and D3100 (ISO 900), but you will easily notice that the D7000 has lower noise than the D3000 (ISO 550) and more noise than the D700 (ISO 2300). Judgments are subjective, and DxOMark is run by camera snobs (and I mean that in a good way) so you will probably find that you're getting very good images at a stop higher ISO than their rating (with some noise in the shadows if you look hard). In part it depends on whether you want to print small 4x6" prints versus big 20x30" posters. If you can tolerate the noise in ISO 6400 pictures, great for you! That means you can use the slow f/5.6 zoom lens that came with your camera rather than having to upgrade to a more expensive f/2.8 lens.

9: Exposure

• The aperture, or size of the opening that lets in light. Aperture is measured in f-stops; the theoretical standard maximum opening size is called f/1, and from there every doubling of the f number (to f/2, then f/4, then f/8) means an opening with half the diameter (and thus 1/4 the area and 1/4 the total amount of light). But very few lens can achieve f/1; each lens has its own maximum aperture; for indoor action I recommend lens with a maximum aperture of f/2.8 or wider. Here is a diagram of relative aperture sizes for a lens with maximum aperture f/1.4:

  

  (Jargon note: the word stop originally meant a physical object, such as the shutter blades we see above that stop light from entering the camera; now "stop" refers to the abstract concept of doubling (or halving) of light-gathering ability, in either aperture, shutter speed, or sensitivity. Two things are confusing about the f-stop numbers. First, f/1.4 seems like a small number but it is a big hole, while f/16 seems like a big number and is a small hole. That's because the "/" in "f/16" is a division sign; the larger the denominator of a fraction, the bigger the number it represents. Second, we don't just have whole numbers in a doubling pattern like 2, 4, 8; we also have intermediate numbers like 2.8 and 5.6. That's because the f-stop numbers refer to the diameter of the circle, but the amount of light is determined by the area, which is proportional to the square of the diameter. So a doubling of diameter (say from f/4 to f/2) is two stops (quadrupling the area), while a doubling of area (a single stop), would change the f-stop number not by a factor of 2 but by the square root of 2, which is about 1.4.

  The lens that came with your camera is probably something like an 18-55mm zoom with a maximum aperture of f/3.5-f/5.6. This means a maximum of f/3.5 at the 18mm (wide) end and f/5.6 at the 55mm (telephoto) end. Lens also have a minimum aperture (usually in the f/16 to f/32 range) which is relevant for landscape and macro photography, but not for action.

• The shutter speed, or time that light is being gathered; this is measured in seconds. As we discussed earlier, you often need a speed of 1/500 sec to freeze the action, but if you can get by with 1/125 sec, then that's 4 times more light. Again, each doubling counts as a stop, so this is a two-stop difference. (See Silverstrandphoto for a nice animation of shutter speed in action.)
• The sensitivity of the sensor to light; this is measured on the ISO scale, as described in the previous section on noise.

(Note: There's a great camera simulator here that lets you see the effects of varying aperture, shutter speed, and sensitivity, as well as overall lighting (EV), distance to subject, and lens focal length.)

We'll first consider a dimly-lit scene at EV 6. If we cut the shutter speed in half 6 times we go from 1 second to 1/2, 1/4, 1/8, 1/16, 1/32, and finally 1/64, which we round off to 1/60. So EV 6 is f/1, ISO 100, 1/60 sec

Of course, most of us do not have an f/1 lens, and we know that 1/60 sec would likely give us severe motion blur. The principle of reciprocity says that if we simultaneously double the ISO and half the exposure time we end up with the same exposure value. Same thing if we half the aperture area (which corresponds to multiplying the f number by 1.4) and double the ISO. (Note: in the song Popsicle Toes (which happens to involve a Pentax photographer), Michael Franks writes "When God gave out rhythm / He sure was good to you / You can add, subtract, multiply / and divide by two." And in fact, multiplying and dividing by two is all a photographer needs to do.)

According to the principle of reciprocity, EV 6 is equivalent to any of the following (I have added annotations for the amount of blur for a moving subject and the amount of noise):

Aperture	Shutter speed	Sensitivty	Reason this is EV 6	Blur	Noise
f/1	1/60 sec	ISO 100	+6 stops in time from EV 0	severe	none
f/2.8	1/60 sec	ISO 800	reciprocity: -3 f-stops, +3 stops ISO from previous line	severe	slight
f/2.8	1/125 sec	ISO 1600	reciprocity: -1 stop time, +1 stop ISO from previous line	noticeable	slightly more
f/2.8	1/250 sec	ISO 3200	reciprocity: -1 stop time, +1 stop ISO from previous line	slight	more

EV 6 is risky territory: assuming you have something like a Nikon D3100 or Canon T2i camera that performs well up to about ISO 800, then no matter what choice you make in the reciprocity trade-off you risk either motion blur or a noisy photo, or both. And that's with a f/2.8 lens! If you only have the f/5.6 lens that came with your camera, your choices are dismal at EV 6:

Aperture	Shutter speed	Sensitivty	Reason this is EV 6	Blur	Noise
f/5.6	1/60 sec	ISO 3200	reciprocity: -2 f-stops, +2 stops time from previous line	severe	more
f/5.6	1/125 sec	ISO 6400	reciprocity: -1 stop time, +1 stops ISO from previous line	noticeable	severe
f/5.6	1/250 sec	ISO 12800	reciprocity: -1 stop time, +1 stops ISO from previous line	slight	extreme

But you can turn that around by investing $100 in a 50mm f/1.8 lens (or $400 in a 85mm or 100mm lens) shooting at f/2:

Aperture	Shutter speed	Sensitivty	Reason this is EV 6	Blur	Noise
f/2	1/250 sec	ISO 1600	reciprocity: +3 f-stops, -3 stops ISO from previous line	slight	slightly more
f/2	1/125 sec	ISO 800	reciprocity: +1 stop time, -1 stop ISO from previous line	noticeable	slight

(You could also invest $2600 in a full-frame camera that does a stop better in ISO (among other benefits). Or you could wait two or three years and the same high-ISO technology will make its way into the sub-$1000 cameras.)

Now let's look on the bright side: in scenes that are lit at EV 8 you're in good shape with any lens:

Aperture	Shutter speed	Sensitivty	Reason this is EV 8	Blur	Noise
f/1	1/250 sec	ISO 100	+8 stops in time from EV 0	slight	none
f/2.8	1/250 sec	ISO 400	reciprocity: -2 f-stops, +2 stops ISO from previous line	slight	almost none
f/2.8	1/500 sec	ISO 800	reciprocity: -1 stop speed, +1 stops ISO from previous line	almost none	slight
f/2.8	1/1000 sec	ISO 1600	reciprocity: -1 stop time, +1 stops ISO from previous line	none	slightly more
f/5.6	1/250 sec	ISO 1600	reciprocity: -2 f-stops, +2 stops time from previous line	slight	slightly more
f/2	1/1000 sec	ISO 800	reciprocity: +1 f-stop, +1 stop ISO from 2 lines above	none	slight
f/2	1/500 sec	ISO 400	reciprocity: +1 f-stop, +1 stop ISO from previous line	almost none	almost none

So much for the theory of exposure. But what do you do in practice? You have four things to worry about:

• Metering: How do you know if the current scene is EV 6, EV 8, or what?
• Intent: Do you want to depict the scene faithfully? Or change the mood by making it lighter or darker? Do you want to show what is in the background shadows, or hide it? If a dancer on one side of the stage is lit at EV 6 and another dancer on the other side is lit at EV 8, you can't get the exposure exactly right on both of them; you have to make a choice. Only you know if you'd rather have one too bright or one too dark, or split the difference--you can't expect your camera to automatically make the right choice about artistic intent.
• Mechanics: What settings do you initially dial in for your camera at the beginning of the day? What do you fiddle with before each shot?
• Postprocessing: What do you do with exposure once you have the image in the editing program on your computer?

Metering and intent: Your camera has a built-in automatic exposure meter, which usually does a pretty good job of deciding the exposure value of a scene. Let it. Although some people succsfully use manual exposure for dance, I find that for the performances I shoot the lighting changes too rapidly and too much from scene to scene and from one point on the stage to another. However, there are a few metering situations that the camera consistently gets wrong, and you will have to step in and make a correction by twisting a dial.

What do I mean by "wrong"? I mean contrary to your intent. There are many ways to interpret a scene. If there is a dimly-lit dancer to the side of the stage, the camera doesn't know if you want to darken the image to make that dancer disappear into the background, or lighten the image to make that dancer one of the points of interest. You can change the camera's exposure to match your intent, but the camera can't always guess what your intent is.

A common problem in dance photography is when there is an area of the image that you would like to be dark black. The default metering scheme of the camera tries to pull detail out of every image; if there is a large black area the camera will try to make it gray rather than black. If you truly want it to remain black, you need to tell the camera that. The way you do it is exposure compensation, which should be set up on a dial operated by your right thumb on the back of the camera. To keep a dark area black, dial in negative exposure compensation: tell the camera you want the picture to be darker than the camera guessed, by moving the dial. In the two images below, I used an exposure compensation of -2 stops.

f/2.8, 1/160, ISO 1600 (EV 6), EC -2	f/2.8, 1/125, ISO 640 (EV 7), EC -2

Another problem is when a white (or other light-colored) outfit is large in the frame. The camera can't tell if the outfit is supposed to be gray or white; it guesses gray and exposes accordingly. You fix that mistake by dialing in positive exposure compensation. In the photos below this was +1 stop.

f/2.8, 1/400, ISO 1250 (EV 8), EC +1	f/2.8, 1/250, ISO 800 (EV 8), EC +1

Mechanics: Given that you're not going to try to manage exposure manually, you have a choice of what are called "shooting modes," but should be called something like "exposure priority modes." I almost always set (and leave) the dial on top of the camera to aperture priority mode ("A" in Nikon; "Av" in Canon). This means that I can adjust the aperture with the dial near my right index finger.

Here's what happens: suppose I am shooting the white dress picture above right. I have already set the controls on the camera to f/2.8, ISO 800, and exposure compensation +1. When I press the shutter button the camera's exposure meter measures the incoming light as EV 7, and adds the +1 compensation to arrive at EV 8. The camera then determines that the shutter speed should be 1/250 to achieve an EV 8 exposure, and takes the image with those settings.

The camera engineers couldn't get the automatic exposure metering right for every picture, so they compensated by giving you several choices of automatic metering systems. (That way, if the exposure is messed up, the engineers can always say "you should have used the other mode!") The metering modes are:

Evaluative (Canon) or Matrix (Nikon), in which the camera's computer considers the whole scene and tries to interpret which parts to pay attention to and which to ignore. It even pays attention to the focus point you have selected. This is the best mode for getting most types of pictures right most of the time, and what I use for most non-dance photos. Center-weighted, an older scheme from the 1980s, that emphasizes the center and ignores the corners of the frame. I tend to use this for dance, not because it is always right, but because when it is wrong it is consistently wrong, and I have learned to use exposure compensation to correct for those errors. (But maybe I really should be using evaluative mode. I'll have to try it some more.) Partial and spot metering, in which the camera computes the exposure value based solely on a small circle (partial) or really small circle (spot) within the frame. In most Canon cameras the center of the frame always determines the spot; in Nikon the spot is the active focus point. If you can keep the circle on a dancer's face then this metering mode will perform very well. There are two problems with it. First, if the dancer's face is in a bright spotlight, but the body is not, this scheme will expose the face properly and underexpose the body. This may be what you want, but if you'd rather have the body exposed properly and risk overexposure of the face, you should use evaluative or center-weighter metering. Second, if the metering spot slips off the face and onto a bright white outfit you'll be underexposed, and if it slips onto a black outfit you'll be overexposed. Therefore I don't recommend partial or spot metering modes for fast action. (They work for picking out the proper exposure for the key portion of a static scene, like a landscape, or a dancer standing still.)

I set the "Av" mode and the metering mode ahead of time and tend to leave them alone. But for each individual shot, I have the option of changing the aperture with my right index finger (to get more depth of field), and I have the option of setting exposure compensation with my right thumb (if the scene has a lot of black or white that will throw off the metering system). Also, if the lighting changes to be much more bright or dim, I will change the ISO (with right index finger button press and then dial adjustment).

There is one more dial that I use regularly: my camera has a shooting mode dial that contains three "custom" modes. I set up C1 to be my regular settings as described above, and C2 to be my "blur" setting: shutter priority mode ("Tv" in Canon) with a shutter time of 1/5 second, ISO 100. I can then switch back and forth easily between blurs and norrmal shots.

So much for dials and buttons; now let's concentrate on what the camera tells you. The great advantage of a digital camera over film is that you can see each image on the camera's LCD screen. You can quickly tell if an image is all wrong, however you won't be able to accurately judge precise focus or exposure on the small screen. Two things are more important than the image itself:

First, set up your screen to show blinking highlights. The idea is that if there is a portion of the image that is so bright that your sensor can't record details, that portion will blink on and off. Look at the display, and if the portion is something that doesn't matter--like a spotlight off stage--no problem. Below we see blinking highlights on the dancer's shoulder (due to a hot spotlight there). This image was shot at +1/3 exposure compensation; it probably should have been about -1/3 to preserve these highlights.

Blinking highlights and LCD display

The second thing is your most important guide to judging your image: the histogram. The histogram shows the relative number of pixels at different light intensities from very dark (on the left) to very light (on the right). If the histogram has a bump (or bumps) in the middle, you're good. If there is a bump crunched up against the left edge that is a potential problem. It means that some details are lost in shadow. That might be fine (you want the unlit edges of the stage to be black) or it may mean that you need to add positive exposure compensation (to get detail back). At the other end, if a bump is crunching against the right edge, you may need negative exposure compensation to bring the details back from the white highlights.

Histogram: levels of light

The histogram helps you with tricky situations like the one below. She has a white outfit, so you have to worry about blowing the highlights (suggesting negative exposure compensation) but also about the automatic metering turning the white to gray (suggesting positive compensation). He has a black outfit, but it is much smaller in the frame, so the main concern is retaining detail (suggesting positive compensation). I shot at -1/3 compensation; was that acceptable? The histogram shows separate channels for red, green, and blue, and one for overall luminance. Together they show that we've done a good job of protecting the highlights (nothing bumps up against the right edge) but that there is a slight problem with the darkest blacks losing detail (they are bunched up along the left, but only a sliver). Not a big problem, but probably this shot would have been better at about 0 or +1/3 exposure compensation.

Histogram display on LCD

Another tricky situation was the shot above of a white dress on a black background captioned "f/2.8, 1/250, ISO 800 (EV 8), EC +1 ." You want to protect the highlights but make sure the dress is white and the blacks are black. Does that mean positive exposure compensation, negtive, or zero? I used +1, which was about right; I can tell by looking at the histogram.

Mechanics of the eye: Beyond dials and displays, my main advice for mechanics is: Don't get fixated on the center of the viewfinder. It is all too easy when there is a lot of action to get tunnel vision. If you see something you like in the center of the frame, take a few shots, but then begin to broaden your tunnel vision. First look to the edges of the frame: is there something distracting there? Something that should be included or removed from view? Have we framed the image well? Then look to the camera display at the bottom of the frame. Are all the settings good? If your shutter speed is showing 1/60 and the dance movements are rapid, you're in trouble--you need to bump up the ISO. But you won't know to do that unless you notice your shutter speed is 1/60. And finally, open your other eye, look around the stage and check if there is something else you should be catching. Then, after the shot (or shots), take time to look at the playback display, particularly the histogram. This process of looking at the display has acquired the pejorative name of chimping (after photographers who exclaim "ooh! ooh! ahh! ahh!" at their own shots) but it is an important part of accelerating the learning, correction, and improvement process.

Postprocessing: One school of thought is to get your exposure just right in the camera. Then you don't have to spend time messing around with your photo editing program ("Damn it Jim, I'm a photographer, not a photoshopper!").

The other school is that you should capture as much digital information as possible in the camera, and then manipulate the image to make it look the way you want. If you subscribe to this school there are two main things to do:

Shoot wide, then crop: instead of trying to get the framing perfect, zoom out a little, with the expectation that you will crop the image in your editing program. This makes action photography easier; if you are shooting wider you don't have to worry as much about a hand getting cut by the side of the frame, you just leave plenty of space and remove the excess space with a crop in your editing program.

173mm: too long; cropped hand	125mm: better; can crop in editing program	125mm, cropped

Expose to the right (ETTR): this technique, originally proposed by Thomas Knoll, the author of Photoshop, recognizes that the highest signal-to-noise ratio can be captured by shifting the histogram as far to the right as is possible without having it actually bump up against the right edge (and thus lose information). If this shift (achieved by positive exposure compensation) makes the image look too bright, then we can fix things by dialing the exposure back down in the photo editing program. The theory is that you get more information (more detail, less noise) if you expose to the right and shift back than if you had exposed "properly" in the first place. There are many good examples of this approach working well, but you do run the risk of clipping the highlights, and it is more work in the editing program.

"Get it right in camera" histogram	"Expose to the right" histogram

If you are in the get-it-right-in-camera school, you will set your camera to capture jpeg images. These have the advantage of smaller file sizes, making them easier to store and share, and also making it possible to take a longer burst of continuous images before your camera grinds to a halt. If you are in the postprocessing school, you should capture raw images, which have larger file sizes but allow you more leeway in making edits, particularly for color balance and exposure.

On the next page we will move away from the mechanics and cover the aesthetics.