Shutter Speeds and Apertures
Depth of Field explained. Panning at slow shutter speeds. Blurred pictures. Selective focus. Blur the background. Tricks and tips for working with shutter speeds and apertures.
An Explanation of
Although, as discussed in exposure, the shutter speeds and apertures are interchangeable as far as exposure is concerned, they each have their own unique effect on the picture. Let's take a look at shutter speeds first as their effect is easily understood. We'll look at apertures on the following page.
The shorter the time that the shutter is open the sharper the photo will be.
If you are taking fast moving objects such as cars or people running you need to select fast shutter speeds to capture the sharpest picture you can. One exception to this is when you are panning the camera with the subject, the object of the exercise here is to render the subject sharply and blur the background, so a careful selection of the right shutter speed to do both is necessary. I often find that a little blur in the right places on a picture gives a greater sense of movement than if everything is pin sharp. This blur, however, must be in the right places, normally we want to see the head and torso rendered sharply but, if the feet and hands are blurred, it can often be a good thing. Blurring the background can also get you out of trouble when there is a lot of clutter that will detract from the main subject. Getting the shutter speed right to render the correct balance of sharpness and blur on any given subject can really only be determined through trial and error. One of the great advantages of the digital camera with it's instant playback is that this learning process can be a lot shorter than it was before. If you have a zoom facility on your playback of pictures, now is the time to get familiar with it. I had my digital camera for quite a while before I realized that, while reviewing my pictures, I could zoom in to check the sharpness.
Not only moving objects suffer from too slow a shutter speed. If you are holding the camera in your hand rather than having it mounted on a tripod, you will see the telltale signs of camera shake (i.e. the movement of the camera) at shutter speeds longer than 1/125th of a second. A secure pair of hands will be able to get away with 1/60th or even 1/30th of a second but the camera would be better mounted on a tripod. Once again I will say at this point that the difference between a mistake and an effect is usually the degree. A small amount of blur would be considered a mistake, whereas really blurred streaks of light can be an interesting effect. It's all a question of convincing the viewer that you did it on purpose.
Tip - When the shutter speed is important as with moving objects, it's a good idea to set the camera to 'Shutter Speed Priority' mode. This is where you select the shutter speed and the camera selects the appropriate aperture according to the light reading.
Of course, if you are taking photos of static objects like houses with a camera mounted on a sturdy tripod, you can leave the shutter open as long as you want without blurring. An interesting by-product of this, if you get to see really old photos taken in the first part of the 19th century, you will see that there are almost no people in the photos at all. That is because the exposure times were so long that the people had walked through the scene without being rendered. For the same reason the really early pictures, in the time of Niépce, the late 1830's, have almost no shadows because the plates took all day to expose and the sun moved across the sky illuminating the scene from both sides.
Getting away from the auto settings.
An explanation of the mechanics of exposure and the side effects of choosing different aperture/shutter speed combinations.
Overriding the automatic metering system.
What they are trying to tell you.
Setting up your camera to take a series of pictures at different exposures.
Another piece of the exposure puzzle.
An explanation, strictly for the jargon heads.
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