Shutter Speed – 31 Days To Better Photography

Yesterday’s Topic: Photography Jargon

Do you remember Shutter Speed from the Exposure Triangle?

[inlinetweet prefix=”” tweeter=”” suffix=””]Shutter Speed affects blur.[/inlinetweet] Get that into your noggin right now.

It does some other things, of course, but the biggest effect it has on the average photo is stopping motion, or not stopping motion, depending on how it is used.  Motion can be in front of the camera or the camera itself moving.  Of course, blur will occur if things aren’t in focus, but let’s assume all is in focus.

Shutter Speed is the speed at which the shutter inside your DSLR (not Point and Shoots, as they use as scan of the sensor instead, which functions the same, essentially) opens and closes to let in light.  That amount of time is expressed as, well, time.  1″ is one second open shutter.  5″ is five seconds open shutter.  1/60 is one sixtieth of a second open shutter.  I know some of you out there hate math, but it will come into play.  Here’s one example.  Which let’s in more light, 1/10 or 1/100?

Answer: 1/10.  Remember: Larger denominator (that number on the bottom of the 1/ fraction) = less light = faster shutter speed.  1/10 lets in more light that 1/100 than 1/1000.  There’s a diagram at the bottom to help with this memorization.

I know that is over simple for those that enjoyed or at least ‘got’ math, but I have taught this enough to know many out there outright hate math.

So where the heck is this shutter and just how does it work?  Let’s look at, what can be loosely called, a diagram of a camera:

When the camera shutter is not pressed, this is how a camera sits.  Light comes in through the lens, is focused, passes through the aperture, bounces off the mirror, bounces twice off the pentaprism and then through the eyepiece so you can see it.  Do you notice the shutter is in a bunch of pieces?  This is to represent the two curtains of the shutter; front and back.  I used four pieces but yours might have more or less.  Here’s a picture looking in through the front of my camera for the curious.

That bright thing at the top is my thumb holding the mirror up and out of the way.  What you are looking at is the front curtain of the shutter.  Notice the individual blades (four of them).  Behind this curtain is an identical curtain.  When you press the shutter release all hell breaks loose.  The mirror flips up out of the way (without the aid of my thumb).  While it is doing that, the shutter curtains performs a little dance that looks like this:

That’s how the shutter functions.  When things get going really fast, the second curtain follows the first curtain, only letting in a smidge of light to expose the sensor for the set time, such as 1/200th of a second.  Like so:

The faster the shutter speed, the more action in front of the camera is stopped.  The slower the shutter speed, the more things in front of the camera can blur.  To break blur down a bit further, let’s think about how you see things.

You see things because light bounces off of them and hits your eye (please don’t make me draw an eye… won’t like it, but it is a lot like a camera). You aren’t seeing the bunny, per se, you are seeing the light bouncing off of it.  This plays into White Balance, covered later. A movie projector shows individual frames on a screen, one after the other, at 24 frames per second (more or less). What happens when two or three of those frames are shown on the screen at the same time and there is slight movement between them? The image isn’t crisp like it is when just one image is shown at a time. This is essentially what blur is.

Blur is represented in the camera when light bounces off of an object and, because of a slow shutter speed where light is allowed to hit the sensor for (relatively) long periods of time, hits the sensor in two spots or more. (Again, I’m only talking about movement blur, not out-of-focus blur.) If that shutter is left open for, say, a second as in the first shutter diagram, the bunny can move a fair amount and light will bounce off of it and hit different parts of the sensor.  Multiple images so close that sharp edges look blurred.

Now this isn’t necessarily bad.  It can be used for some cool effects and we’ll cover Pan Blur, Light Trails and long exposures with flash later on in the month.

Make sense?

Moving objects need a faster shutter speed (1/1000 is faster than 1/60 is faster than 1″) to be able to make them appear sharp and not blurred.  This is also true of you, the camera holder, moving.  If you aren’t still and move the camera while shooting and the shutter speed is slow, say 1/10, then things will blur.  We’ll go over How To Hold A Camera later as well.

An important thing to know about shutter speed is it is linear in the amount of light hitting the sensor.  Meaning 1″ is twice as fast as 2″.  1 is half of 2.  1″ lets in half as much light as 2″.  1/2″ lets in half as much light as 1″.  1/4″ lets in half as much light as 1/2″.  1/8″ lets in half as much light as 1/4″.  1/15 (there is some rounding in cameras these days) lets in half as much light as 1/8″. 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000 to the highest most cameras will go of 1/8000.   Each of these halving of light (or doubling of light if you go the other way on the scale) is called a stop.  A stop is a very important concept and it will come up again and again.

In this case, going from 1″ to 1/4″ is two stops less light.  That is, 1″ to 1/2″ was half as much light (1 stop) and 1/2″ to 1/4″ was half again as much (1 stop) = 2 stops.  Those good with math can just divide or multiply the fractions by 2 for each stop of light.

Pop Quiz:  How many stops less light is there between 1/60 and 1/1000?  I’ll reveal the answer tomorrow.

Now then, before I wrap this up, here’s a piece of a puzzle which will be revealed this week.  It’s meant as a quick reference and helps some people remember their shutter speeds and what they do.  The arrow represents more light hitting the sensor down to less light hitting the sensor.  If you want to take pictures of slugs, you can get by with slower shutter speeds.  If you want to take pictures of bunnies on scooters, you’ll need faster shutter speeds.  The word Blurry is to indicate if you are hand holding a camera, or if there is movement in front of the camera, it is likely to be blurrier at the top of the scale.  Of course, this scale extends past both 1″ and 1/250

As always, fire away with the questions!

Next Up: Aperture explained

31 Days To Better Photography is a series written by professional photographer Peter West Carey on The Carey Adventures.Com. The series is designed to unravel the mysteries of photography so you can take better pictures. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

17 Replies to “Shutter Speed – 31 Days To Better Photography”

  1. DonnaKay

    I love your teaching style – it is so easy to follow. I am still learning a lot. I have used good cameras for years, but only recently (past year or so) have I really gotten seriously into learning exactly what it is I’m doing, and how to get the results I’m looking to get. Your information is clear and easy to understand. Hope to see more of your stuff published! Wish you were closer so I could take classes from you!

  2. Jack from eyeflare travel

    Probably the most straightforward and well-illustrated way of explaining this I’ve seen. You really should try for a photo how-to book, most are too heavy on the gear side, and light on actually taking photos… Your teaching style, as mentioned above, is really good.

  3. Erin K

    I like the mechanical explanation of the shutter. I don’t think I’ve ever seen a diagram like that and it’s very informative. I can keep that simple diagram in my head, and picture it when i’m using the camera. Nice bunny on scooter, too.

  4. Michael Stagg | Maikeru Foto

    One of the best tutorials I’ve seen on the subject; well done, sir! Quick question: In the begin of this post you mention that point and shoot cameras use sensor scans instead of actual shutter blades. Is that true for advanced point and shoots like the Canon G12 as well?

      • Terrance Smith

        I am trying to wrap my brain around that, but I was always tought in school that in measuring it was 1/4 half of that was 1/8 half of that was (1/16) and maybe i am over thinking this. Do you see what I talking about. Or should i put down the camera before I hurt my self lol

    • Peter West Carey Post author

      While the size of a hole gets cut in half, so does the amount of time that a shutter is left open. You’re thinking of it right. 1/8th is half of 1/4, which means the shutter is open for half as long. When a shutter is open for half as long it lets in half as much light. Less light = darker image (as long as the aperture and ISO don’t change).

      Thinking of it in timing, 1/8th is FASTER than 1/4, right? Twice as fast. Meaning the shutter is staying open for half as long, as mentioned above. The same way 1 second is faster than 2 seconds. 1 Second is half the time that 2 seconds is and therefor, lets in half as much light.

      Does that help?

      • Terrance Smith

        Thank you I think I got it now. btw I agree with the others that I like the way you teach and how you take the time to make sure the slow one comes along. lol see you on day 6. and thank again

  5. Fotofanatix

    Bloody Awesome Tutorial on Shutter Speed.
    Easy to understand and follow, you have a unique style Peter and it seems we all like it!

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