Tag Archives: camera

Exercise: Depth of Field

(This shall forever be known as the too-many-yellow-rulers lesson. Sorry!)

f32Up ’til now, you’ve been just reading the exercises and maybe doing them in your head, but not getting the camera out and trying them yourself. It’s OK– I’m lazy too. This one is different though. You’ll want to get the camera and do the exercise. If you don’t, I’ll hunt you down and scowl at you.

In this exercise, you’ll get firsthand experience with how aperture affects depth of field. In order to do the exercise, you’ll need a large flat surface with some sort of measurements, or sharp regular pattern. Some things that would work well:

  • a tile floor with high-contrast lines
  • a striped or checkered blanket with high-contrast lines
  • a long tape measure

You’ll need about five feet of this patterned surface, and you’ll need to be able to get fairly close to it, so that you’re looking down the length of it. See the tape measure picture at the top for an example of what I mean. You’ll also need enough light to take a steady picture at f/16.

Set your camera to aperture priority mode, f/16, and manual focus. If you’re not in a very bright area, set your ISO to 1600, or as high as your camera will go.

Stand near your patterned surface so that you’re looking down the length of it. Pick a spot in the middle, and manually focus on it. Remember that spot, because you’ll be coming back to it. Once you have the image in focus, take a picture.

Without changing your position, change the aperture to f/8. Point your camera at the exact same spot, and take another picture. Do the same thing at f/4, and as wide as your lens will go.

f4f8f16

Pull the photos into your computer where you can examine them more closely, and you should have a set that looks something like the photos above. The photo taken at f/4 will have a narrow band in the center that’s in focus, and the rest will be blurry. The f/8 photo will have a wider focus area, and f/16 will be much wider.

For extra credit: repeat the exercise, but this time don’t take pictures. Instead, use the depth-of-field preview button on your camera to see what the shots would look like. Feel free to try out the apertures in between the ones I suggested too. You should see a much smoother transition of focus than at the widely-spaced apertures, of course.

The astute… OK, the barely-conscious reader will notice that the example photos in this exercise are also in the page header. I originally shot these as examples when I was teaching SSA! as a live class, and I wanted samples to hand out. I was happy when I saw the results. The students in the class seemed to grok depth of field as soon as they saw the images, and they had a field day duplicating them with their own cameras.

Now it’s time for you to go out and play. Put your camera in aperture priority mode, and wander around taking pictures. Create some blurry backgrounds and some crisp ones, just like you’ve always done, but this time do it on purpose. You have the power– use it.

Next lesson:  ISO: What is it?

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Depth of Field: Another View

We already know that depth of field is how much of your picture is in focus. In particular, it’s what distances from your lens are in focus. Is it a narrow range? A wide one?

Here are a few sample images that show you how depth of field actually works. I took these very carefully– I placed the camera on a tripod, and focused at exactly the 12-inch mark on the ruler. I made sure to keep everything lined up as carefully as possible, and then took shots at f/4, f/8, f/16, and f/32. Most lenses don’t go down to f/32, but this one did so it was good for shooting these sample photos:

f/4f/8
f/16f/32

At f/4, pretty much the only thing that’s in focus is the 12-inch mark itself– you can’t even read any of the other numbers. At f/8, you can start to see the numbers 11 and 13 come into focus, though they’re still a little soft. At f/16 the numbers 10-14 are pretty clear, and you can actually make out other numbers. At f/32 you can read the entire visible length of the tape measure, and the majority of it is fairly sharp.

I recommend clicking through on the above images and studying the larger images, since they give you a pretty good idea of how the depth of field breaks down as a percentage of the image. If you have a Flickr account, you can click the “all sizes” link above the photos to see them in their original eight-megapixel glory.

The astute reader will notice that these are the same images that are at the top of every page on this blog. I originally took them to use as examples when I was teaching Stop Shooting Auto! as a class for my coworkers, and I instantly loved them. They seemed to produce an aha! moment for everyone who saw them.

Let’s go back to our six-year-old’s landcscape for a bit. I’ve added something to the illustration this time– an indicator of what percentage of the image would probably be in focus at various apertures. The places where there’s a straight yellow line are the areas that will probably be in focus, and the angled lines indicate what will be out of focus– it’ll be just a little bit soft close to the solid yellow line, and stuff far away will be very blurry. Note that I guessed at these based on my experience rather than using any super-magical scientific math wizardry to figure it out. Treat them as rough guidelines rather than hard scientific fact.

Here’s how it might look at f/4:

MountainFlower f/4

and at f/8:

MountainFlower f/8

and finally, at f/16:

MountainFlower f/16

Clearly, if we want our image to be in focus across pretty much the whole range, we should use f/16 or smaller. If we want to blur most of the image, we should use a large aperture like f/4.

How am I doing? Is aperture less scary now? Does it sort of make sense?

Next lesson:  Exercise: Depth of Field

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Quick Exercise: Focusing

This is a really simple exercise that will help you think about focusing and depth of field. It’ll only take you a minute. Grab your camera.

Find a place where there are things at various distances from you– pretty much any place will do. Put your camera into manual focus mode, and turn the focusing ring all the way either direction.

Look through the camera and see what, if anything, is in focus. We’re not trying to focus on any particular object, but rather just look to see what’s already in focus. Keep looking as you slowly turn the focusing ring all the way to the other extreme. If you want to, repeat this a few times.

As you turned the dial, you probably noticed that things close to you came into focus first and then the farther-away ones did. (Maybe it was the opposite direction. It all depends upon which direction you were turning the ring.) You can imagine that your focus point is a person who walks closer to you or farther away from you as you turn the ring. The person will always be in focus, as will some area around them.

Now look at the top of your lens. You’ll probably see a bunch of numbers with an infinity sign (a sideways figure-8) at one end. Those numbers indicate how far away the focus point is at any given time. If you turn the focusing ring so that the focus is at infinity, things far away from you will be in focus and stuff that’s close will be blurry. You’re smart– I bet you can guess what happens to far away things when you turn the focusing ring the other way.

Next up: another way to look at depth of field. (It’s important. I’m going to repeat myself.)

Next lesson:  Depth of Field: Another View

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Aperture: Why You Care

flower f/22At this point, we know that aperture is how big the opening in the lens is when you take a picture. We know that big numbers mean a small opening (and therefore less light getting in), and small numbers mean a large opening and more light. f/4 is a large aperture, which means lots of light. f/16 is a small one, and only a little bit of light.

Aperture does way more than control how much light gets into the camera. Those “f-stop things” are one of the most useful tools in photography. Let’s look at why.

I stopped at a park on the way to work this morning so that I could take pictures of flowers to use as examples in this lesson. The flowers weren’t particularly remarkable, but they were useful patient subjects. Here’s one example. You’ll probably look at it and think, “Yeah, a yellow flower”, and see it as fairly messy and uninteresting. That’s because it is messy and uninteresting and an entirely unremarkable picture. Its purpose in life is to serve as a bad example, and it does a rather fine job of it.

Here’s the exact same flower from the exact same angle, but it’s a much more compelling photo. When you look at it, your eye is drawn to the flower, and it isn’t distracted by all the stems and leaves and junk and crap and ick in the background. The only difference between the two images is that in the first one the background is in focus, and in the second it’s soft and blurred.flower f/4

“Hey, that’s cool! How can I do that?”

It’s easy! All you have to do is pay a little bit of attention to what’s going on, and change your aperture to get the effect you want.

“Huh?”

It’s time for me to demystify another technical term– this time, it’s “depth of field”. Depth of field is really just how much of your image is in focus. There’s a lot of complicated stuff underlying it, but the basic premise is really simple.

When you take a picture, it’s almost always true that some things in the image will be close to the lens, and others will be farther away. The way depth of field works is very simple– if your lens is very wide open (i.e. small f-stop numbers) only a narrow range of distances will be in focus. If your lens has a very small aperture (a big f-stop number), then a very large range of distances will be in focus.

Confused? I don’t blame you. Let’s have our six-year-old draw us another picture. Imagine that you’re walking through a meadow. In front of you is a yellow flower. A little bit farther back from the flower is the goofiest-looking tree you ever did see, and in the distance is a snow-capped mountain range.

While walking through a meadow, you come upon this scene

Clearly, the flower is very close to your lens, the mountains are far away, and the tree is somewhere in the middle. Let’s pretend that you’re going to take a picture of this idyllic scene, and you decide to focus on the tree.

If you keep your lens wide open, the tree will be in focus but the flower and the mountains will be blurry. If you use an aperture that’s in the middle of the range then you can get the tree and the mountains in focus, and if you use a very small aperture then you can get everything in focus. The former might be useful if you wanted to focus on one thing (say a person standing in front of the tree) and the latter is great for landscape photography.

Think of your depth of field as a stripe that is centered at whatever you focused on. Whatever is inside the stripe will be in focus. If your lens is wide open, then the stripe will be very narrow. If it has a very small aperture, then the stripe is very wide.

I’ll close today with two excellent illustrations from the nature photography of Joe Decker. One shows the power of a shallow depth of field, and the other illustrates what a wide depth of field can do. I highly recommend clicking through to see larger images, since the thumbnails don’t do them justice. Oh, and Joe’s flowers are much better looking than mine.

You’re probably still confused by this, and I don’t blame you. In the next lesson, I’ll leave the fluffy flowery examples behind and show you depth of field in a completely different way. If you don’t want to wait, stick your camera in aperture priority mode and take a bunch of pictures at different f-stops. The wonderful thing about digital photography is that you can play around a lot. The feedback is cheap and very fast.

Next lesson: Quick Exercise: Focusing

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What does f/8 really look like?

Yesterday I talked about apertures (a.k.a. f-stops) and how they work. As the old saying goes, a picture paints a thousand words, and this is after all a photography blog. Without further ado, I present f/8:

f8

Pretty cool, huh? That’s what it would look like if you could look inside your lens while you were taking a picture. As you can see, the blades of the diaphram (that’s the thing in the lens that opens and closes to change the aperture) have closed down to make an opening that’s much smaller than the full opening of the lens. What this means is that a lot less light will get into the camera than if the lens was wide open.For reference, here’s what the lens looks like wide open:

f1_8

Notice that you don’t see the blades of the diaphram at all. If you were to look into your camera’s lens right now, you’d see something just like this because the diaphram only closes while you’re actually taking a picture.

The lens in the picture is a Canon 50mm f/1.8 lens. (Aside: if you have a Canon dSLR, I highly recommend buying this lens. At a retail price of less than $80, it’s a screaming deal.) Since it’s an f/1.8 lens, it has a maximum aperture of… that’s right, f/1.8. The minimum aperture is f/22, which is pretty typical for non-specialized lenses.

Here’s what the full range of the lens looks like. I didn’t take a picture of every possible setting, but you can probably figure out for yourself what the ones in-between look like:

f1_8 f2 f3_2
f/1.8 f/2 f/3.2
f4 f5_6 f8
f/4 f/5.6 f/8
f11 f16 f22
f/11 f/16 f/22

A lot of what I’ve been saying about aperture probably makes more sense to you now that you’ve seen those pictures. All other things being equal, a photo taken at f/2 is going to be about a bezillion times brighter than one taken at f/22. That’s because the amount light that comes in through a great big window is way higher than the amount that comes in through a pinhole.

By the way, I apologize for the reflections on the lens. Taking pictures of glass is notoriously difficult, and I was feeling a little bit too lazy to set up enough of a lighting rig to do a better job. Mea maxima culpa. (If you want to learn sophisticated lighting techniques, I recommend the excellent Strobist blog. Stick around here for a bit and master the basics first, though.)

Now you’ve seen my f-stops. Want to see your own? Here’s a little mini-exercise to do just that.

Most modern cameras have a button called depth-of-field preview. On my Canons, it’s if you’re looking at the camera from the front, the DOF preview button will be next to the lens, on the right side, toward the bottom of the camera. It’s just below the button that you use to take the lens off. If you can’t find yours, check your camera’s manual.

Now, set your camera for manual mode, and an aperture of f/8. We don’t care about any other settings right now, because we’re not going to take a picture. Look into your lens, and press the depth-of-field preview button. Did the diaphragm close? If so, you now know what f/8 looks like on the lens you’re using. Try different apertures to see how it changes.

If your camera doesn’t have a DOF preview button, there’s another trick you can use. Set the camera for manual mode, f/8, and about a 20-second exposure. Press the shutter button (yes, take a picture) and look into the lens. You’ll have 20 seconds to look into the lens and see the diaphragm. Like before, you can try out different apertures and see what they look like.

When you started reading this blog, you probably kept your camera in automatic mode all the time. And now, a short time later, you actually know your f-stop from a hole in the ground. If I’ve done a good job, your brain isn’t even bleeding out your ears.

As it turns out, aperture is one of the most powerful tools in photography. In the next couple of lessons I’ll show you why.

Next lesson:  Aperture: Why You Care

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Exercise: Shutter Speed

8In this exercise, we will take several pictures to illustrate how shutter speed affects the resulting image. We’re not going to take any great pictures here, but the ones we do shoot should help us get a better feel for the nuts and bolts with shutter speed.

You’ll need a friend with a flashlight, or some sort of light source that he can swing around. In my pictures I used a glow poi (basically an LED on a string) but you can just ask your friend to hold the light in his hand and move it around. You’ll also need a camera, of course, and a not-too-bright room. Oh, yes, one other thing. You’ll also need a beer or other Appealing Beverage to thank your friend for the help. If you know someone who wants to learn to use his dSLR better as well, the two of you can take turns being the photographer and the helper.

If you have a tripod, it will be useful for this exercise. Instead of holding the camera when I tell you to, put it on the tripod. If you don’t have a tripod that’s OK… blurry pictures won’t be a big problem. If you really want the shots to be perfect, find a table or something to brace the camera on when you take the photos.

Control PanelSet up your camera: To begin, set your camera to ISO 400 (if you now how… if not, don’t worry about it), shutter priority mode, and manual focus. Have your friend stand facing you. Pick a spot that will let you get his upper body in the frame plus a couple of feet on either side, and manually focus the camera on him. Focus doesn’t have to be perfect, but it should be good enough to get the light source pretty clearly. Set your shutter speed to one second. On my Canon that’s the number one with two tick marks after it.

Now, ask your friend to turn on the flashlight, point it at you, and start moving it in a circle in front of him. Ideally he should be doing this so that he makes one circle every second, but friends are unpredictable (especially if he’s already had that beer) so any speed that’s somewhere in that vicinity will work.

Holding the camera as steady as you can, take a picture. Yes, it’s a one-second exposure and you’re going to shake, but that’s OK. We really just care about how far the light moved. One second sure is a long time, isn’t it? When you’re done, check out the picture on the camera’s display, and you should see a circle of light.

Now, set the shutter speed to 1/2 second (indicated by 0”5 on my Canon), ask your friend to make a light circle again, and take another picture. Repeat this for 1/4, 1/8, 1/30, 1/125, 1/250, and 1/500 second.

500When you’re done with this, you’ll wind up with a set of photos of progressively smaller arcs of a circle of light. At 1 second, you should basically have a full circle. Half a second should get you approximately half a circle of light, and so on until you get to the very fast exposures. Look closely at the ones that are 1/125, 1/250, and 1/500 of a second. When I did this exercise, 1/500 pretty much froze the action, but 1/250 and slower had blurs of light.

When I did this exercise to create sample images, I put the camera on a tripod and used a remote shutter release rather than asking a friend to help. As I mentioned earlier, I also used a glowing ball on a string rather than flashlight. Still, the resulting images do a pretty good job of showing movement. I have them all in my photography class set on Flickr, and they’re tagged “light circle exercise”.

Note that some of your photos may have come out much brighter than others. That’s OK! What happened was that your camera wanted to make all of the pictures bright and shiny and happy at whatever shutter speed you chose. At the slower shutter speeds it probably closed the aperture down to block out some of the light. As you chose faster and faster shutter speeds, the camera opened up the lens to let more light in but at some point it ran out of room to do this because the lens was already as wide as it would go. When that happened, the camera just did its best but the photos started getting darker as the shutter speed got faster. For the purposes of this exercise that’s perfectly OK. In fact, it’s a good way to see how your camera’s photos turn out when the camera is starved for light.

When you’ve completed this exercise, you should have a bunch of pictures with streaks of light in them. The Guggenheim won’t be beating a path to your door over them, but you’ll have practiced setting your camera’s shutter speed to a pretty wide range of settings, and you’ll have a pretty good understanding of how much motion there is at a specific speed.

Oh, yes. Set your camera back to whatever ISO (probably 100) you usually use, and set the lens back to autofocus. That will save you from some confusion the next time you try to use the camera. In general, it’s a good idea to pick a set of “normal” settings for your camera and leave the camera in that configuratoin whenever you put it away. That way, if you want to pick it up and shoot something quickly you won’t have to worry about undoing whatever you did last week.

If you want to practice some more, find some other moving object and start taking pictures of it. If you have dogs or small children, you can probably persuade them to run around in the park while you take pictures. Cars, water, anything that moves somewhat predictably will be good practice for you.

If you want to share your photos from this exercise, I recommend uploading them to Flickr and tagging them with “stopshootingauto” and “lightcircleexercise” so that other people can see them just by looking for those tags.

Next lesson: Quick review, what we’ve learned so far

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Exercise: exposure modes

Are you ready for the first exercise? Great, let’s go. If you haven’t ready the last lesson on how exposure modes work, you’ll want to do that first. In this exercise, we’ll try out the various exposure modes in order to learn how the controls work.

OK, grab your camera. It doesn’t matter what lens you use, but try to find a place with a lot of light and something at least marginally interesting to point the camera at.

The first thing we’re going to do is put the camera in aperture priority mode. If this is the first time you’ve taken your camera out of its everything-automatic rut, this may be scary for you. Don’t worry, I’ll be right here to hold your hand. Now, take a deep breath and turn the dial to Av, A, or whatever your camera calls it.

See? That wasn’t so bad.

Now, pick out something nearby that you can focus on. Maybe it’s a picture or a piece of furniture or a tree, but pick something that isn’t going to move around a lot. Now, look through the viewfinder of your camera and focus on the thing that you picked out. Press the shutter button halfway, and you should see a display in your viewfinder that will tell you what the aperture and shutter speed are set to.

Turn whatever dial it takes on your camera to open the aperture as wide as it will go– remember, that’s the lowest number. It may be as low as 1.4 or 1.8, but more likely your lowest setting will be somewhere between 2.8 and 5.6. It doesn’t matter for now. Keep pointing the camera at whatever object you picked out.

If you did that quickly enough, which you probably didn’t, you’ll still have a display in your viewfinder. If not, push the shutter button down halfway to get it back. Make a mental note of what shutter speed the camera has picked out. Now, turn the aperture dial a few clicks. Do you see the shutter speed change? (If the display goes away, just keep pressing the shutter button halfway.) Keep doing this until the aperture is as small as it will go– most likely, that will be around 22, but your lens may be different.

Did you notice how the shutter speed changed automatically every time you changed the aperture? That was your camera’s meter picking out the right shutter speed to go with the aperture you chose. It’s possible that your camera had trouble with the highest and lowest settings, and couldn’t find a shutter speed fast enough or slow enough to work. If so, it probably kept the needle all the way on the left or right of the meter display, and maybe flashed it or beeped or complained in some other way. If so, remember that for the future. It’s your camera’s way of saying that something’s not right.

Now, let’s do the same thing but in shutter priority mode. Set your camera to Tv or S or whatever. Look through the viewfinder, and press the shutter button halfway. Turn the magic dial to change the shutter speed, and watch the selected aperture change. If you pick a really fast shutter speed like 1/1000, there’s a good chance you’ll get to see how your camera complains about bad exposures.

OK, there’s one more step, but before we take it you probably need a quick break from all this scariness. Get up, walk around the room, do a jumping jack, grab a beer, or do whatever it takes to get past all the scariness I’ve thrown at you.

Are you back? Excellent. Now, we’re going to do one more scary thing. Set the camera to manual mode. Ready? Deep breath. OK, go.

Still with me? Great! Now, set your aperture to f/8, using whatever control your camera uses to change the aperture in manual mode. Now look through the viewfinder and press the shutter halfway. See the indicator on the meter? It’s probably way off to one side. Keep looking through the viewfinder while you turn whatever dial changes the shutter speed. Keep doing this until the indicator is right smack dab in the center of the scale. When you get it there, take the picture.

Guess what? You just took a photo in manual mode. If you view it on the camera’s LCD, you’ll probably see that it looks pretty good. Pretty cool, huh?

If your room isn’t very bright, there’s a chance that you couldn’t make that work. If so, set the aperture as wide as it will go and try again, or go somewhere with more light.

Next lesson: Shutter speed exercise

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How your camera works– exposure modes

ModeDialOK, this is what you’ve been waiting for… we’re about to take our camera out of automatic mode. How do we do that? It’s really very easy.

Somewhere on your camera there’s a dial that looks a little bit like this one on my 5D. It will have several settings to choose from, and may have many more than what’s shown in this photo. In order to set the exposure mode, you turn the dial so that the appropriate setting is lined up with the indicator line on the side. The line is a little bit hard to see in this photo, but the camera is in M mode. M is for manual, Magic, Master of the universe, and My favorite mode.

What are all those other modes?

  • Green box: the camera just does everything for me
  • P: program mode, which is much like the green box but a little less neurotic
  • Tv: shutter priority mode
  • Av: aperture priority mode
  • M: manual mode
  • B: bulb mode
  • C: custom function mode (which I’m going to ignore)

I shoot with Canon gear, and therefore I’m most familiar with Canon’s controls. Those are also the cameras that I have sitting around to use as examples. (If anybody wants to send me a Nikon so that they can have equal representation, I’d be happy to go the extra mile.) I believe that Nikon calls their controls Auto, P, S, A, and M for Automatic, Program, Shutter Priority, Aperture Priority, and Manual. Other brands will have very similar functions– if you can’t figure out what they are, consult your manual.

In Auto and P modes, the camera basically just does everything for you. Typically, Auto mode is extremely obsessive about it, and won’t let you change any of the settings on your own. P mode is kind of a laid back version of Auto, one that will set the shutter speed and aperture for you, but not ignore you if you try to change something else.

Aperture priority and shutter priority are the real workhorses, and many people find that they use aperture priority more than anything else. You might too, once you figure out how they work. In aperture priority mode, you pick your own aperture, and then the camera’s meter figures out what shutter speed to use. As you can probably guess, in shutter priority it’s just the opposite– you pick the shutter speed that you want, and then the camera picks an aperture. Pretty easy, huh?

Manual mode is the final mode that you might want to use on a regular basis. In manual mode, the camera keeps its grubby little paws off the settings, and you get to choose both the shutter speed and the aperture. That sounds like a scary amount of power, right? Well, it’s not so bad. The camera’s not going to do any work, but it will still give you information. Even in manual mode, the camera’s meter works just fine, and you can use the display to help you find the right exposure.

Just for completeness, bulb mode is a special manual mode. In bulb mode, you press the shutter button once to open the shutter, and press it again to stop. This seems like a weird thing to do, and you’re right, but it’s occasionally useful for things like taking pictures of stars. You’ll probably never need to use bulb mode, but tuck the information into a corner of your brain in case it ever comes in handy.l

You’re probably wondering how you set the aperture and shutter speed on your camera. Frankly, I have no idea but if you bring it over here I’ll figure it out and tell you. Or, you can grab the manual and look it up. Here’s how mine work:

Canon 5D: There’s a dial right behind the shutter button– it controls the shutter speed. There’s a thumb wheel on the back of the camera that controls the aperture.

Canon Digital Rebel XT: There’s a dial right behind the shutter button. In aperture priority mode, this button controls the aperture. In shutter priority button, it controls the shutter speed. In manual mode, that dial controls the shutter speed. In order to set the aperture in manual mode, you press the top button (labeled Av +/-) on the back of the camera and hold it down while turning the dial. Yes, that’s a little confusing to describe. It’s actually pretty easy to do, and once you get the hang of it you’ll find it quite easy.

Next up, our first exercise!

Next lesson: Exposure modes exercise

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How your camera works– the meter

This is part two of how your camera works, and it’s a little bit more complicated than the first round. I’ll try to keep it as simple as possible, but some of this is pretty close to magic.

As I explained earlier, when you take a picture the aperture closes down part of the way, the shutter opens, and then the sensor records the light it saw. There’s a step that happens before that, and it’s a very important one.

Your camera is surprisingly smart for such a small piece of gear, and it does a lot of sneaky stuff when you aren’t looking. You’ve probably noticed that if you leave the camera in automatic mode, it pretty much just figures out how to take a picture that looks pretty good. Sometimes it guesses wrong, but most of the time it gets pretty close to a good picture. How does that happen?

Your camera has a built-in light meter that measures how much light is coming into the camera. Just before you take a picture, when the shutter button is halfway down, the camera very quickly measures the light coming into the camera and then picks out the settings it thinks will be best for a good picture. If you’re in a dark bar, the camera will want the lens to be wide open and the shutter to be open for a long time. In bright daylight, the camera will want a smaller opening and a quick shutter speed so that the photo doesn’t get overexposed.

MeterIsHappyI’m sure you’ve seen the weird scale thing somewhere on your camera. There’s almost certainly one in your viewfinder, and quite possibly also one on a screen on the top or back of your camera. It usually has numbers that go from -2 to +2, with a bunch of tick marks in between and a line that moves around seemingly of its own volition. That thing is a display of your camera’s meter, and it’s really very simple to understand. The camera moves the line around to let you know if it thinks the shot is going to be underexposed, overexposed, or just right. When the line is right smack dab in the center, as it is in this photo, the camera is very happy about the exposure. That doesn’t mean the exposure will be perfect– cameras are far from perfect at guessing this stuff. They’re pretty good, though, and the camera’s meter will usually be a very good starting point.

If the line is to the right of center, that means the camera thinks that the shot will be over exposed– the photo will have too much light. A much more common situation is that the line will be way over on the far left, which means that there’s not enough light and the photo will be underexposed. In automatic modes, the camera will do its very best to get that line in the middle of the display, but sometimes it just won’t be able to even at the slowest shutter speed and the widest aperture. Later we’ll talk about ways of handling that. For now, just try to get more light if you can.

Modern cameras generally have very sophisticated meters with all sorts of different modes. You’ll often hear terms like spot, zone, center-weighted, evaluative, partial, super duper, whizbang, and confusing. Camera review sites will list the various modes as badges of honor, and gear geeks will discuss them ad nauseum.

Don’t worry about those for now, and just leave yours set to whatever the camera’s default is. Right now, all you really need to know about metering is that your camera knows how to measure light and pick out shutter speeds and apertures based on the light it sees.

OK, I’ll tell you just a little bit more. Your camera’s default mode is probably one where the middle of the picture matters a lot, the edges barely matter at all, and the stuff in-between matters a little bit. That’s because most people put the important stuff in the middle of the picture. Somewhere down the line we’ll talk about different metering modes and why you might care, but that’s pretty far away. It’s entirely possible that you’ll never have a reason to use anything but the camera’s default mode.

Next lesson: How your camera works– exposure modes

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Shutter speed, why you care

FourLittleAngelsOK, those spinning light pictures are kinda cute, but why do you really care about shutter speed if you aren’t trying to capture fire dancers? In short, the shutter speed gives you artistic control of the way your camera captures motion.

One day at work, I heard jets flying very low over my San Francisco office. I happened to have the camera on my desk, so I grabbed it and ran up to the roof to see what was causing the ruckus. I’d completely forgotten that it was Fleet Week in San Francisco, and the Blue Angels were putting on a show for us. I grabbed my longest telephoto lens and started snapping. Since the planes were going by at several hundred miles per hour, I needed a very fast shutter speed to avoid blurriness. This photo was taken at 1/1600 sec, which is pretty speedy.

What if you want to take a picture of your son’s little league game. He’s the pitcher, so of course you want to capture him for posterity. What shutter speed should you use? Well, it depends. Do you want to freeze him in motion just as the ball flies away from him? If so, you should probably use a shutter speed of around 1/500 in order to freeze the motion. Do you want to capture blur from the motion of his arm and see the ball traveling through the air? To achive this result, use something slower, maybe 1/80 or 1/60.

JohnInMotionHere’s a neat picture of my drummer friend John. The shutter speed on this was 1/80 sec, which froze almost everything the picture but captured the motion of his drumsticks and his hands. This produces a much more interesting and dynamic shot than if the drumsticks had been completely unblurred– you can almost hear the crash of the cymbal as the fast-moving drumstick comes down on it.

There’s also an interesting remedial component to shutter speed that you should be aware of. Have you ever taken what you thought was a wonderful photo, only to find out later that it was shaky and blurry? It turns out that humans aren’t all that great at holding perfectly still. When we try to take a picture with a slow shutter speed, it doesn’t really matter what our subject is doing. The photographer (that’s us!) wiggles and jiggles around so much that even a picture of a rock will be blurry.

If you’re holding the camera in your hand rather than supporting it on a tripod or some other solid surface, you need to use a fast enough shutter speed that your own motion won’t blur the photo. Some photographers are better at holding still than others, but everybody gets camera shake if their shutter speed is too slow. A general rule of thumb is that your shutter speed should be no slower than the focal length of your lens. For example, if you’re using a 50mm lens, use 1/50 or faster. If you’re using a 200mm lens, use 1/200 or faster. Unless you have nerves of steel, that’s the absolute slowest that you should try to hand-hold a shot. Even you might not be quite that steady; it pays to experiment and figure out how steady your own hands are.

IMG_8485Newer image stabilizing lenses will let you exceed that guideline, but they’re relatively expensive, and they aren’t the cure-all that some people make them out to be.

Thus far, we’ve pretty much just focused on reasons that you might want a fast shutter speed. What about a really slow one? Fireworks are one example. You need a tripod or some other way to stabilize the camera, but fireworks are surprisingly easy to shoot. For this shot, I set the shutter speed to 4 seconds and then did my best to time the shutter so that it opened just before an explosion.

Here’s another great example. Noted nature photographer Joe Decker uses a slow shutter speed to capture the movement of water in this stunning image. Incidentally, Joe has graciously allowed me to use some of his photographs as illustrations on this site. You should check out his work.

Next lesson: How your camera works– the meter

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Filed under Lesson, shutter speed