Photo Basics: Shutter Speed

   If you have not read my other Photo Basics post about Aperture, please go read that one and come back.

   Shutter speed, for me, is something I am always keeping an eye on. Light changes when you are outside. A cloud could move in front of the sun, a subject may move into a shadow or out of it, or it could be much later in the day than when you first started shooting. When you are not in control of the light, you have to rely on what you do have control of. You have control of your camera.

   However, you only have control of your camera if you have gotten out of your automatic settings. If you have not done that then you have no control over anything except when you take the photo. Once you are in your manual setting you are in control of aperture, shutter speed, and many other settings. It's a whole different ball park once you have changed that dial to "M" and these "Photo Basics" posts aim to help you out in that regard.

   Previously I said that changing your aperture will brighten or darken an image, but it also effects your depth of field, or how much you have in focus. So what if you like what you have in focus or out of focus but it is still too bright or dark? Well you have other controls to get the exposure right without having to change your aperture. Shutter speed is one of them.

   Shutter speed is denoted as a fraction. When you look at the back of your camera it will usually say something like 1/100 or 1/1000. If you remember all the way back to 5th grade math you will remember that the more numbers in the denominator, the smaller the fraction actually is. Same is true for photography. First let me explain what your shutter is.

   When you put your eye to the viewfinder of your camera, the image you are seeing is what the lens is seeing. So in essence you are looking through the barrel of the lens.

But not quite. 

   What you are actually seeing is the image after it has hit a series of mirrors inside your camera and then reflected back into your eye. These mirrors are in the shape of a pentaprism and that part is quite complicated and not really of importance to this post. However, one of these mirrors is important, or rather where it is placed is important. There is a mirror directly behind your lense, this mirror is sitting on your shutter. The shutter blocks light from hitting your sensor(or film) inside your camera until the moment you hit the "shutter button" and take a photo. (This is far different for mirrorless cameras and they use an infrared electronic shutter but that is new technology and something to learn later. If you are a technology nut like I am this is incredibly fascinating stuff.)

   So when you do hit that shutter button what happens? Well for one you hear a little "click" from inside the camera and then you have your image. (Unless you're shooting film then you have your exposed piece of film which needs to be processed into a negative then developed... but you get the point.) That "click" is your shutter flipping up out of the way so that light may enter from the lens and into your camera and onto your sensor. (edit: 4-15-15 I don't know what I was trying to say here but that's not exactly what I meant. This made it sound like your shutter and mirror are one and the same which they are not. You mirror flips up out of the way and then your shutter slides out of the way of the sensor to allow light to hit it.) As a result, you cannot see anything from within the viewfinder for a split second because that mirror on your shutter is no longer reflecting light into your camera's pentaprism. This is called viewfinder blackout. It's less cataclysmic than it sounds...

   How long your shutter is out of the way depends on that fraction we spoke about earlier. That fraction represents a fraction of a whole second. So 1/100 is a hundredth of a second, 1/1000 is a thousandth of a second and so on. So how does that time determine how bright or dark an image is? Well since 1/100 of a second is longer than 1/1000 (1/1000 is the smaller fraction of time.) then more light has time to flood into your camera making an image brighter.

   "So Alex, why would I ever want a faster shutter speed?" Well for one thing, if you are in a very bright situation you want a fast shutter speed because then too much light will hit your sensor and make your image bright white. But beyond that it depends on your subject.

Fast moving subject slow shutter speed

   When you have a fast moving subject, and you choose a slow shutter speed, the subject will appear to streak across the frame. This is called motion blur. Sometimes this is bad, and sometimes it is good like in the image above. I used a very slow shutter speed with my camera on a tripod to make the merry-go-round appear to be going 100mph. That brings me to the next point. With night shots you want a longer exposure, at times your shutter speed may have to be longer than a full second. This is impossible to do without setting your camera on a tripod. Our hands are always moving whether from breathing or just being unsteady, this motion will transfer to your camera in a longer exposure.

Fast moving subject and fast shutter speed freezes motion

   Then you have fast moving objects which you do not want to be blurred in the frame. Such things as sports shots require the action to be frozen in time. The only option available to you is to shoot with a very fast shutter speed. However, this also requires a lot of light. If you are in bright daylight, chances are you will have no problem getting a very fast shutter speed and properly exposed image. But things like high school football games are usually played at night with stadium lights that are great for our eyes, but horrible for cameras. In this case you will also need a lens capable of a very large aperture to allow more light and counteract the loss of light from a fast shutter.

   It's really a lot less complicated than it sounds. With the invention of digital imaging it has become far easier to learn proper exposure by pure trial and error. Simply look at your scene, determine if you want a lot in focus or a little, figure out if it is a bright scene or a dark one, then guess a shutter speed and aperture combo. Once you take a photo you can determine from there whether it needs to be brighter, freeze more motion, freeze less motion, and so on. You can also use the camera's light meter as a general guideline. True mastery of your craft however means knowing how light works and being able to correctly capture a moment in time as it happens.



Hey everyone, did you like this post? Did you hate it? Did I miss something or do you still have questions? Please leave me some feed back. I enjoy answering questions, that's why I write posts like this. Also, is there something you would like me to cover or something you would like to see in the future? I have plenty of ideas on what I would like to write about, but ultimately my blog is for the interest of my readers. So if you have an idea please tell me, if you have a question, perhaps it will be a big enough question for me to write a whole post about. As always be sure to share this blog with everyone you know. Until next time, whip out your camera and make a scene!