Tuesday, April 20, 2010

"Freeze!" - Understanding Shutter Speed

So far we've reviewed one of the three elements of the "exposure triangle". Last week we discussed aperture and how we can use aperture settings to determine how much light we allow into the camera when capturing a photo. We also discovered that we can impact "Depth of Field" (or DOF) by manipulating aperture settings to determine how much or how little of the image appears in focus.

This week we discuss the second element of the triangle - shutter speed. While aperture is responsible for the size of the opening through which the light travels, shutter speed determines the duration of time for which the light is allowed through that opening. Shutter speeds are typically expressed in fractions of seconds (1/60s, 1/200s, 1/1000s, etc), but can be substantially longer (seconds, minutes, or even hours). Shutter speed determines how fast or slow you "freeze" the action. Too slow and you end up with blurry images. Too fast could result in dark images or images that don't convey the "motion effect" you were after. How do you know what the right shutter speed is? Well, there's no magic formula as it depends on the type of image you're trying to capture, but there is a good rule of thumb. When shooting hand held, your shutter speed should generally be "one over your focal length". In other words, if you're shooting at 200mm, your shutter speed should be at LEAST 1/200th of a second. Vibration reduction (also referred to as image stabilization) technology can help you to get sharp hand held images when violating this guideline, but generally speaking, when you need to shoot at slower shutter speeds a good tripod support is a must.

So what if you want to take a picture at 200mm and 1/200th of a second, but you're camera is only shooting at maybe 1/60th of a second? How do you get to 1/200th? Great question :). This is where the "exposure triangle" comes into play. With the tools we've learned so far, one option would be to open your aperture and allow more light into your camera to potentially get faster shutter speeds. Next week we'll learn about another option and the third component of the triangle - ISO.

That's a wrap for this week's tip. Take some time to explore "Shutter Priority" on your camera and the effect manipulating the aperture has on shutter speed. If you're not familiar with how to identify your aperture or shutter speed when taking pictures, spend some time with your camera manual as these are critical pieces of information to know.

Until next time, keep click'n.


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