Category Archives: shutter speed

Action Shots– A Quickie

IMG_8742I promised to write about histograms, but I’ve been pretty busy. However, here’s something quick I wanted to share. I went whale watching today with a couple of friends, and so of course I took the camera along. The thought process that I used here is pretty much my standard way of thinking about what I want to shoot.

Packing the camera bag was easy– the Canon 70-200 f/4L IS was the perfect lens choice, since it was long enough to bring the whales in close, and as a bonus image stabilization would help a little bit with the motion of the boat. Well, maybe, but it couldn’t hurt.

What about settings? I didn’t really care about depth-of-field other than wanting to have enough to get my subject in focus, so I set the camera to aperture priority mode and f/8. I realized that I was going to be shooting moving animals from a moving boat on choppy waters, and so shutter speed would be critical. I set the ISO to 100 and pointed the camera at the water, looked through the viewfinder, and pressed the button halfway to see what the camera would want to do. It picked 1/320 for a shutter speed. Under normal circumstances that would be fast enough, since it was faster than one over the focal length of the lens (1/200 in this case), but with all of that motion I wanted something faster. I took a wild guess and thought that 1/800 was a good minimum.

If I got 1/320 at ISO 100, then at ISO 200 I should be able to shoot 1/640. That still wouldn’t be enough, but at ISO 400 I should be able to shoot 1/1250. (Note: shutter speeds don’t always change in precise multiples of two. It’s confusing until you get used to it.) Since 1/1250 was well above my arbitrarily-chosen 1/800 threshold, ISO 400 should be perfect.

The sky was gray when we left the harbor, but I expected some of the fog to burn off over the course of the trip. I knew that I would have to doublecheck the settings if it started getting sunny– the fastest shutter speed my camera could do was 1/4000, which meant that I only had around two stops of room before my camera would be forced to overexpose the image. Sure enough, the sun came out a few hours later, but I was still able to shoot at around 1/2000. Otherwise, I would have either dropped down to ISO 200 or changed the aperture to f/11.

The thought process for this is one that you should use whenever you pick up a camera. What do I want this image to look like? What range of apertures and shutter speeds will get me the results I want? What camera settings should I use to get the right apertures and shutter speeds? As a novice you won’t always know all of the answers to those questions, but you can start guessing. “Do I want the background blurry or sharp? Do I want to capture or freeze motion?” Just answering those two questions before you pick up the camera will give you a huge leg up in getting the image you want.

Oh, yeah, a quick note about the gull. When I first looked at this picture on the camera’s LCD, I was rather shocked– the image looked blurry! It was taken at a shutter speed of 1/2500, so that hardly seemed possible. Either I’d seriously misjudged what shutter speeds would work, and I didn’t think I had, or something else was amiss. I zoomed in on the image and realized that the fuzziness I thought I was seeing was really the transition in feather colors at the rear edge of the wing. The image was actually so sharp that I could pick out individual feathers quite clearly.

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What Is Bulb Mode?

I’ve touched on this briefly a couple of times, but it bears a little bit more discussion.

Bulb mode is kind of a special manual mode on your camera. On some cameras there’s a B mode on the exposure mode dial, but on others bulb is just a shutter speed– set the camera to M mode, change the shutter speed to 30 seconds (not 1/30, but half-a-minute 30 seconds) then go one step further. Once you’re there, set the aperture that you want to use.

Now what? Press the shutter button, and the shutter opens. Let go and it closes. You can keep the shutter open for as long as you want to, until your finger gets tired or your camera runs out of battery.

In order to make effective use of bulb mode, you really need another piece of hardware– a remote shutter release of some sort. I’m pretty sure that there are wired shutter releases available for all dSLRs and probably all film models too. In the simplest version, you plug the cable into the side of the camera, and when you press the button on the cable it activates the shutter. (This works in all camera modes, not just bulb.) In bulb mode, holding the button down holds the shutter open. Slightly fancier models have a shutter lock so that you can activate the shutter and then walk away for a while.

Many cameras also have wireless shutter releases available. These basically function the same way, except that they sometimes have two-press operation– press the button once to open the shutter. Press it a second time to close it. If you have a Canon Digital Rebel (original, XT, or XTi) the Canon RC-1 is a valuable addition to your kit. It lives on your camera strap and is completely unobtrusive when you don’t need it. If you want to release the shutter remotely, you just pop the RC-1 off of the strap and it’s ready to go. When you’re done, pop it back onto the strap and it’s out of your way. It’s not just for long exposures– it’s valuable whenever you want to be away from the camera, such as when you want to be in the photo. When I used a Rebel XT all the time, I was always reaching for the RC-1.

Some cameras may require you use the self-timer setting in order to use a remote shutter release.  Consult your manual for the details of your specific model.

Why would you want to use bulb mode? Mostly it’s for very-long exposures of over 30 seconds, but it has other uses too. I use bulb mode a lot when I’m shooting fireworks– I try to open the shutter just as a rocket is going up, and close it as the explosion fades. You can set the camera on a tripod at night and shoot the path of stars moving across the sky, or capture blurs of cars driving through the city.  Though I have no first-hand experience, bulb mode is also used for taking pictures of lightning strikes.  I’m sure there are plenty of creative uses that I can’t even imagine.

IMG_7804Another cool technique that uses bulb mode is light painting. Light painting involves taking the camera into a darkened room, opening the shutter, and then using light sources (LEDs, flashlights, whatever) to paint light onto an object or just onto the sensor itself. While it didn’t use bulb mode, the image at left was taken by opening the shutter in a dark room then moving an LED glow ball in front of the camera.  As you might have guessed by now, I like playing around in front of a camera with bright objects in a dark room– you just never know what kind of cool image you might wind up with.

Bulb mode is a specialist tool, but it’s a really useful one to know about.  You probably won’t need it very often, but sometimes it’s the only real choice for getting the shot you want.

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How the settings play together

After trudging through all those scary numbers, we now know that ISO 200 is twice as fast as ISO 100, that 1/60 second is half the time of 1/30 second, and that f/4 is twice as fast as f/5.6. If I did my job well, we even learned that without anyone’s brain dripping out of their ears and onto their keyboards.

Note: the word “fast” in photography generally means “captures more light” when it’s talking about ISO or aperture.  When talking about shutter speed, though, “faster” means just the opposite– 1/60 is faster than 1/30, but 1/30 lets in twice as much light.  It’s confusing.

What might or might not be obvious now is that we can change two different things and keep the exact same exposure. For example, each of these settings will produce the exact same exposure:

ISO 100 f/4 1/60 sec baseline
ISO 100 f/2.8 1/120 sec faster (wider, more light) aperture, faster (less light) shutter speed
ISO 200 f/4 1/120 sec faster ISO, faster (less light) shutter speed
ISO 200 f/5.6 1/60 sec faster ISO, faster (wider, more light) aperture
ISO 400 f/5.6 1/120 sec ISO four times as fast, shutter speed twice as fast (less light), aperture half as fast (narrower, less light)

The first line is our baseline measurement. On the second one, we opened up the aperture wider to let more light in. In order to keep the exposure constant, we need to capture less of the light, so we keep the shutter open for half as long.

On the third and fourth lines, we increase the ISO, which records more light To balance it out, we either keep the shutter open for less time, or we make the aperture smaller– either of those will let less light in.

The fifth line is tricky! We’ve quadrupled the ISO, which means we’ve increased it by two stops. In order to compensate for that, we made the aperture smaller by one stop and we also made the shutter speed faster by one stop.

The fancy technical term for this is reciprocity– it really just means that if you change one setting, you can balance it out by changing another one, and get the same result.

So how would you use this? Here’s an example. Let’s say you’re taking a picture of a group of people, some of them standing behind the others. You put the camera in aperture priority mode and pick f/4 and ISO 100. When you try to take the shot, you find out that the best shutter speed is 1/30, and that’s too slow for you to hold the camera steady– you need at least 1/50 sec. What do you do?

Well, you can try using f/2.8 and 1/60. That will get you the same exposure, but at a faster shutter speed. But wait… now you’re at f/2.8, and when you focus on the front row of people the back row is out of focus, or vice versa. You really need f/4 to get everyone in focus.

Finally, you set the ISO to 200, which lets you use an aperture of f/4 with a shutter speed of 1/60. Voila! You get your shot.

The way exposure settings play together is a little bit like having a squishy ball in your hand. When you squeeze one part to make it smaller, another part gets bigger. Squish two parts, and the third one gets a lot bigger. Squish squish squish.

Easy, huh?

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Filed under Aperture, ISO, Lesson, shutter speed

How much more light? How much less?

At this point, we know what’s bigger and smaller, faster and slower. We know that f/4 is a bigger opening than f/8, and therefore lets more light in. We know that a shutter speed of 1/200 is faster than 1/100, and therefore lets less light in. We know that ISO 400 is faster than ISO 200, and therefore captures more light.

You’re with me, right? Good.

I’m about to throw a little bit of math at you, but I promise it’s only a tiny amount. No, really. All we really have to do is multiply by 2 or divide by 2. That’s easy, right? Take a deep breath. Ready? Let’s go.

How much more light does a shutter speed of 1/100 let in compared to a shutter speed of 1/200? The obvious guess is twice as much, and it’s precisely right. Any shutter speed that’s half as fast will let in twice as much light. Any shutter speed that’s twice as fast will let in half as much light. So 1/200 is half as much light as 1/100. 1/400 is half as much light as 1/200, and is therefore 1/4 as much light as 1/100. Double the bottom number means half as much light. Easy, huh?

Let’s look at ISO next. Do you think that ISO 200 is twice as much light as ISO 100? Bingo! Just like shutter speed, changing the setting by 2 means twice as much light, or half as much light. ISO 200 is half as fast as ISO 400. ISO 100 is half as fast as ISO 200, so it’s 1/4 as fast as ISO 400. Again, all you have to do is multiply or divide by 2, and you’re good.

Now aperture. Do you think f/4 is twice as fast as f/8?

Sorry, but this time it’s a tiny bit more complicated. When it comes to aperture, making the opening half as big means you’re only going to get 1/4 as much light. Making it twice as big means four times as much light. If you don’t want to know why, skip the rest of this paragraph. Our aperture is basically a circular opening. Remember back in high school, the area of a circle is pi-r-squared? Changing from f/4 to f/8 means that the radius of the opening is divided by 2. Because the area is changed by the square of the radius, the area of the opening is divided by 4. The amount of light coming in is directly related to the area of the opening, so the amount of light coming in is also divided by 4.

As it turns out, the way to cut the light in half is to change the aperture by a factor of about 1.4. In this case, f/5.6 is half as much light as f/4, and f/8 is half as much light as f/5.6.

Let me put it all into a nice tidy table, in case that’s easier to follow:

setting Starting setting 1/2 as much light 1/4 as much light
ISO 400 200 100
Shutter Speed 1/100 1/200 1/400
Aperture f/4 f/5.6 f/8

Now, a tiny bit of jargon. Whenever you increase or decrease the amount of light by a factor of 2, that’s called a stop. A shutter speed of 1/400 is one stop faster than 1/200. An aperture of f/4 is one stop wider than f/5.6. ISO 100 is one stop slower than ISO 200.

In summary: for shutter speed and ISO, changing the number by a factor of 2 means twice as fast or twice as slow. For aperture, changing the number by a factor of 2 means four times as fast or four times as slow. Half as much/twice as much is really all of the math you need to know in order to be a competent photographer.

A bonus note for those of you who are vaguely mathematically inclined. Remember that I said that changing the aperture setting by a factor of 1.4 meant twice as much or half as much light? The astute reader will note that 1.4 is (approximately) the square root of 2. That’s not a coincidence.

Next lesson:  How the settings play together

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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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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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