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Shutter Speed And The Exposure Triangle

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Welcome to another edition of Let’s Talk Photography! This week I’d like to share my thoughts on shutter speed. As we’ve discussed previously, the most important thing to learn in photography is the exposure triangle. This will be your key to being able to make the necessary adjustments to get a great exposure in any situation. Two weeks ago, we took a look at the aperture and how it controls the amount of light that is entering your camera through a mechanism that opens and closes to adjust the light. Now, we’re going to take a look at the shutter and how it manages the light that is entering your camera using a different mechanism.

Unlike the blades of the aperture, the shutter is more like two barn doors that open and close at timed intervals to reveal the light to the sensor. The doors of the shutter are called “curtains.” I wrote a brief explanation of these curtains in a past article and asked you to imagine you were sitting in a theater and the curtains are closed. Only, instead of being closed in the middle of the stage, they are closed off to the right side of the stage. Now, imagine the first curtain opens from right to left and you can see the stage. When the curtain gets half way across, imagine the second curtain starts to close behind it and follows until it is all the way over on the other side. You would see a portion of the stage at any given time going from right to left, but never see the entire stage. Now, imagine this took one full second to take place. That’s what your camera is doing to expose the scene to the sensor and allow the light to be recorded. The only difference is, the curtains in your camera open up and down instead of side to side. But, you should get the idea pretty easily when you think of the stage analogy.

When you set your shutter speed, you are setting the speed at which the second curtain, also known as the “rear” curtain, follows the first curtain (yep, you guessed it, the “front” curtain). The slower you set the speed, the slower the second curtain will follow the first curtain. The slowest speeds will allow the entire sensor to be exposed for long periods of times and the fastest speeds will only allow slivers of light to hit the sensor at any given moment throughout the exposure.

So, why would you need to be able to change the shutter speed? Let’s say you’re shooting a portrait and you want the aperture to be set at a very low number (large opening) so you can have that beautiful bokeh effect in the background. When you set the aperture very low it allows a lot of light to shine in through the lens. This could cause your portrait to be very bright and overexposed, therefore, you must be able to control the light without changing the aperture. This is one way the shutter will help to balance the exposure triangle. When you set your aperture to a low number, you must speed up your shutter to decrease the amount of light that is let in to the sensor, or shoot “faster,” so to speak. If you’re shooting a landscape and you want the entire scene to be in sharp focus, then you’re going to need to set your aperture at a very high number (small opening) so your depth of field is as large as possible. This will restrict the light that is coming in through the lens so you’re going to have to set your shutter speed very slow so the sensor is exposed to the light for a longer period of time. This is sometimes called “dragging the shutter.”

But, controlling the light isn’t the only reason you need to be able to slow down or speed up your shutter. Shutter speed also allows you to shoot fast moving action or very slow exposures for catching light trails. Let’s look at the photo of the hockey player. Hockey is one of the fastest sports there are to shoot, and it’s very difficult to capture the extremely fast changes in the scene. To capture a photo at the very moment before the stick hits the puck, you must be able to shoot extremely fast. In this photo, I have my shutter speed set to 1/400th of a second. Because the lighting is not the greatest in the arena, I have to be careful not to shoot too fast otherwise I won’t have enough exposure to get good detail in the photo. To compensate for the fast shutter speed, I must have the aperture set at a very low number, in this case it’s at f/3.5 which means only a very small portion of the scene will be in focus so I must be dead on to get the player’s face in focus. Those numbers still leave the photo very dark so I’m brightening it by having my ISO set at 1600 which makes it grainy but this is really the best setup for shooting the Xpress players. The tennis photo is shot in the sunlight so the ISO is much lower at 100, the aperture is the same f/3.5, and the shutter speed is only 1/320th of a second. If I shot this at 1/400th, then the ball would be perfectly frozen in the scene and it would look fake and motionless.

The fireworks at this year’s Christmas parade downtown are much different. These are shot at f/16 so more is in focus and ISO 100 because the light is so bright that the sensor doesn’t need to be so sensitive, but the shutter speed is set at six full seconds so the light trails are recorded as the pieces of shimmering light are flying through the air. When I shoot fireworks, I often put the shutter speed on BULB mode so I can use a remote to hold the shutter open as long as I need to get a beautiful display of light.

I hope this helps you understand your camera’s shutter. Now get out and play around with it and see how the shutter speed changes your photos when you leave everything else set the same.

Until next week, happy shooting!

Is there a topic that you’d like to learn more about? Send feedback, share your photos, or offer topic suggestions to talkphotos@ecklof.com. If you’re looking for a place to connect with local photographers in Chautauqua County, search for the group “Shoot ‘n Share Chautauqua” on Facebook.

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