Exposure Triangle: Shutter Speed

To look at shutter speed more effectively, I’m going to split the two words up and describe each on its own.

Shutter

If the pupil of your eye is like the aperture of your camera, and regulates the amount of light we need for proper exposure, than the shutter is like your eyelid. Not only does it keep our eyes moist, clean, and free of bug splatter it also regulates the amount of time light stays in our eyes. Have you ever tried sleeping with your eyes open? Probably haven’t had much success with that have you? If you close your eyelid you take away the light and when you open them again you allow the light to enter. It’s kind of like when we have tried to take a picture with the lenses cap still on (and yes, I said we) not really possible right? You need that light to get into the camera somehow, but just like that creepy relative that shows up to your home at awkward times of the day without being invited, knowing how long it should stay is another matter.

Speed

Sometime in our lives; we have either stolen, driven, or have had the honor of being a passenger in a vehicle during one or both. And as we travel down the road ignoring the black and white signs with insignificant numbers blurring past, we have had our head banging session interrupted by the blue and red lights flashing behind us, causing us to look down and realize to late that 55mph in a children at play zone probably wasn’t a good idea. If we look at speed as we do in the car, we have three important little letters MPH that means miles per hour. Let's take a math quiz to explain this further, If you are traveling at 60MPH how long will it take you to travel 60 miles? put the pencil down, and stop the frantic scribbling, three sheets of paper is enough. One hour right? Because there is 60 minutes in an hour, and if we are traveling at 60 miles per hour, we are driving a mile every minute. Now if word problems weren’t enough I’m going to hit you with fractions, because in photography we deal with fractions of speed. So, we know that there is 60 minutes in an hour, so one minute is 1/60 of an hour, and there is 60 seconds in a minute, making one second 1/60 of a minute, so how many parts are in a second? 60? 200? 2000? We know that a second is pretty fast already but to get proper exposure we have to go even faster sometimes. If I haven’t utterly confused you already, let’s look at an inch on a ruler.

Think of the inch as 1 second, if we go to 1/2 we are increasing the speed by 1/2 a second. If we go to 1/8, we are increasing the speed even more, and if we go to 1/16 we increase the speed even faster. So if you were able to divide the inch into 2000 lines allowing us to see 1/2000th of that second it would be extremely fast. The same is true with our cameras, 1/60th of a second is much slower that 1/2000th of a second.

Shutter speed also affects our images when it comes to freezing action or causing blur in our photographs, I’ll explain that later. In this lesson we are dealing with exposure and light so I'll continue with that. Simply put, If it is dark (little light) we need to keep the light in our camera longer to expose the image (lower shutter speeds, sometimes even whole seconds if it’s really dark). And if there is a lot of light, we need to get rid of the light quicker, as to not over expose our images (high shutter speeds).not only do we need to regulate the amount of light with the aperture; we also need to regulate the time the light sticks around with the shutter speed. Next we will discuss the ISO which regulates how sensitive our camera is to the light, wouldn’t want to hurt our cameras feelings now do we?