Shutter Speed Explained

Let me be clear: I am not a photography expert. I'm not even a photographer. I'm just a dude with a camera who likes to learn stuff.  I don't know much about photography or taking pictures, but I like to try out new things and see what happens.  I also enjoy teaching, and since one of the best ways to learn a subject is to teach it, I figured it would be cool to write some blog posts about photography as a way of helping others learn while at the same time advancing my own skills as well.  I have already covered, to some extent, depth of field and aperture, and this post will be about shutter speed with hopefully another post to follow about ISO.  Since this article builds on concepts discussed in those articles, I would advise you to give them a look-see before reading further.  And if you're not the reading type, here's a video I made that kind of explains things too:



As one of the three components of the holy trinity of photography, shutter speed is an essential element to understand if you want to dig into photography a little deeper.   In photography, a camera's shutter functions the same way as your eyelids do: when your eyelids are open, light comes in.  When your eyelids are closed, no light comes in.  This analogy doesn't carry a whole lot of weight though, because on a camera the eyelid, or shutter, is almost always closed (unless you are actually taking a picture). But on your eyes the eyelid, or shutter, is almost always open (unless you blink or go to sleep).  Still, it's not entirely dissimilar and hopefully thinking about the shutter as an eyelid for your camera will help you understand what it does and why it's important to control it.

A digital camera works by allowing light to pass through a camera's lens and on to an image sensor, and exactly how much light is let in is determined by the aperture and the shutter speed.  Think of a swimming pool with a plug in the side:

Let's say you want to drain ten gallons of water.  You have two choices:

1. Use a small plug but leave it open for a long time
2. Use a large plug but leave it open for a short time

Both solutions will yield the same result, and the same principle holds true for photography.  The amount of light hitting the image sensor is like the amount of water you let out of the pool.  To let in enough light to take a proper photo, you have a couple of choices:

1. Use a small aperture but leave the shutter open for a long time
2. Use a large aperture but leave it open for a short time

Another option is to use a higher or lower ISO, but we'll tackle that issue another time (for now, if you aren't sure what to do just leave your camera Auto ISO, or else use 200 for outdoors and 400-800 for indoors).  Shutter speed does not work on its own--it have to work in conjunction with other settings on your camera like the aperture size.  But understanding how to properly use the shutter will help bring you one step closer to mastering your camera.  Whee!

Let's use a couple of case studies to help explain shutter speed.  Say your kids are playing outside and you want to get good pictures of them on the swings, playing ball, or just running around.  There is plenty of light to work with since it's a sunny day, so in order to take your pictures you have the same two options as before.  However, since your kids are running around and making a great deal of movement, if you leave the shutter open for too long they will get blurry:

The couple stood very still while their kids ran around.
Image courtesy of Flickr user Steve Bremer.
Used with permission.

In the above photo, the shutter was left open for one-tenth of a second. While that might not seem like much time, it is actually way too long if your goal is to capture your kids clearly in the middle of doing something. In the above photo, the one-tenth second shutter speed was used intentionally to create a pleasing artistic effect, but if your kid is kicking a soccer ball around or flying high on a swing, chances are you would rather have a clear picture without any blur.  In this case, a much faster shutter speed would be advisable.  But how fast?  That's up to you to decide, and every situation will be different.  A setting of one-two-hundredth (1/200) of a second would probably work, but most cameras today can go as fast as one-four-thousandth (1/4000) or one-eight-thousandth (1/8000) of a second--enough to capture even the fastest motion without any blur:

Image courtesy of Overcoming Busy. Used with permission.

In the above photo there is no blur at all, even though the girl is clearly moving fast. The photographer used a very fast shutter speed in order to freeze the action, and was likely shooting with a DSLR camera because they tend to focus much quicker than point-and-shoot pocket cameras (and a quick focusing time is necessary, because the girl is moving so fast!).

But what about the aperture?  Let's go back to the swimming pool analogy for a bit.  On a bright sunny day there is plenty of light available, so you can use a large aperture for a small depth of field (if you want to focus just on one kid) or a small aperture for a large depth of field (if you want to focus on all the kids).  Either way there will be plenty of light coming through to the sensor to make for a good picture.

But what if there isn't enough light?  How about another case study to illustrate this.

Say you are out for a walk in the evening and want to snap a few pictures of your family.  The sun is about to set, so there just isn't a whole lot of light available (i.e. the swimming pool from my earlier example is really low).  In order to let enough light in to take a photo, you still have the same two options as before but the problem is that even a larger aperture like f/2.8 might not let in enough light for the picture to turn out.  The only solution here (for our purposes, anyway--there are other solutions but they are a bit too complicate for this just-the-basics tutorial) is to use a longer shutter speed.  This will allow enough light to pass through the lens and on to the image sensor, but the catch is you will have to tell your family to hold very still.  When leaving the shutter open for a longer period of time, like one-half of a second, any movement at all will result in a blurry photo.  This also means you will have to hold the camera very still too, and possibly even use a tripod.  Of course you could always use a flash, but that might result in harsh light on your family and undesirable shadows too.

Leaving the shutter open for a much longer period of time, like one, five, ten, or more seconds can also produce some interesting and artistic results such as this:

Image courtesy of Reddit user heisakukosawa. Used with permission.

If you want to try your hand at a similar type of photograph, simply put your camera on a tripod, point it at a busy street at night, and keep the shutter open for several seconds.  Some cameras even have a "Bulb" mode which allows the shutter to stay open for as long as you want! This is really cool for taking pictures of stars moving across the sky or capturing lightning as it comes in with a springtime thunderstorm.

But what about one of the most basic questions: how on earth do you set your camera's shutter speed?  On most pocket cameras, you can't.  This is left up to the computer inside the camera, but if your camera has a dial that says "M A S P" or "M Av Tv P" you're in luck! All DSLR cameras have these options, and some pocket cameras do too.

M = Manual. You have full control over the aperture and shutter values.
A/Av = Aperture mode.  You control the aperture of your lens, and the camera determines the appropriate shutter speed.
S/Tv = Shutter mode. You control the shutter speed, and the camera determines the appropriate aperture setting.
P = Program auto. The camera determines what it thinks are the best aperture and shutter values.


Turn the dial of your camera to S/Tv, and you will have the option to set the shutter speed, while letting your camera choose the best aperture. (If you are feeling brave, go ahead and use Manual mode in which you set both the aperture and the shutter speed.) Just remember that there is no one correct shutter value to use in any given situation. It's up to you to decide what to use, give the kind of photo you want to take. A word of warning though: The standard "Kit" lens that comes with most DSLR cameras won't let in enough light to take good pictures with a fast shutter speed in low-light situations like indoors or at night. So if you are trying this out for the first time, make sure you are outside or in a situation with plenty of available light. Once you feel comfortable setting the shutter speed on your own, you can start taking photos indoors or with less available light and you will have a better idea of what speed to use given the photos you are taking.

As I have said many times on this blog, I shoot with a 50mm f/1.8 lens which means that even on fast shutter speeds it lets in enough light to take decent pictures.  I like to take pictures of my son, and since it's winter and we spend a lot of time indoors, I need to have a shutter speed that is fast enough to eliminate the blur of his movements but slow enough to let in enough light. As a result, I shoot most of the pictures of him using a shutter speed of 1/60, and let the camera figure out the appropriate aperture (which usually ends up being around f/2.8 or f/1.8 especially in the morning or evening when there just isn't much light to work with). Since I shoot in RAW it's easy to lighten up the photo afterwards, but even RAW files have their limits and there really is no substitute for a properly exposed photograph.  Any slower than 1/60 (such as 1/45, or 1/30) generally results in too much blur since my 18-month-old son tends to move around a lot, but any faster than 1/60 (such as 1/90) and the lens simply can't let enough light in to take a good picture.  Most pocket cameras have image sensors and lenses that are so small they need to use a flash in order to take good pictures in low light, but it's certainly worth experimenting on the manual controls to see what results you can achieve.

So there you go! I hope you learned something, and if you have questions just leave me a comment and I will do my best to answer. Remember that the most important rule is to get out there and just start taking pictures!