Saturday, August 29, 2009

Shutter Speed

Shutter speed refers to the amount of time that your image sensor is exposed to light. Refer back to my earlier post on the anatomy of a DSLR, and you’ll see that the shutter is in front of the image sensor. So, the “faster” your shutter speed, the less time light (which is the image) is hitting the image. “Slower” shutter speeds, means that the image sensor is exposed for a longer period of time.

Shutters are normally very fast… fractions of a second. That’s all the light you need to make a photo. Shutter speeds range from about 1/6000th of a second to about 8 seconds. The light you have available to take a picture, determines how you set your shutter speed. 8 seconds, (denoted 8” on the back of the camera) would be used for incredibly low light (ie, Taking pictures of the stars). 1/6000th of a second (denoted 6000 on the back of the camera) would be used for taking pictures when there is a lot of light available (ie, middle of the day, pointed at the sun).

Under normal, daytime conditions, I shoot in the range of 1/60th to 1/3200th of a second. I generally try to use the fastest speed that the light will allow. The faster the shutter, the less chance I will cause the image to be blurry by shaking the camera. This type of blur is called “motion blur”, and causes everything in your pictures to appear out of focus. If I’m going to hand-hold my camera (not use a tripod), I won’t set it below 1/60th of a second. It is next to impossible to hold still enough at this speed.

Take a look at the three photos below to see the effects of shutter speed. I’ve kept all the variables the same (Subject, time of day, aperture, white balance, iso camera location) except shutter speed.


This image has the “fastest” shutter speed. 1/2500th of a second.

Sunglasses 1/2500 sec f/5.3


This image is a little slower. 1/2500th of a second.

Sunglasses 1/1250 sec f/5.3


This is the slowest image 1/800th of a second.

Sunglasses 1/800 sec f/5.3

Notice that the photos get darker the faster the shutter speed is. This is because less light is hitting the sensor. 1/2500th of a second’s worth of light vs. 1/800th of a second.

So, when shooting in the manual mode, I set the aperture, and then adjust the shutter speed until the image is exposed properly. The camera will also do this automatically for you if you shoot in Aperture Priority Mode.

1 comments:

Sara Reid said...

An excellent article very well supported by some superb images. I think it is a bad idea to talk about shutter speeds without mentioning the roles of ND filters. Also other filters as well since they reduce shutter speed. And in many cases that is a good thing since it will give us more saturated colours.

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