Examine the photograph to the right. As you'll notice, the flower in the foreground is sharply focused and the background is out of focus.

This was caused by selecting a specific aperture setting and a shutter speed setting.

The photographer had intended this effect.

Let's review aperture and shutter speed and then we'll have you decide how to recreate the photograph.

Two things that the photographer can control on the camera is the shutter speed and the aperture opening of the lens.

Shutter speeds have numbers like 1/15, 1/30 and 1/60. What do these numbers mean and how do they contribute to the properties of a photograph?

Apertures have numbers like f4, f5.6, f8. What do these numbers mean and how do they contribute to the properties of a photograph?

This is a traditional camera. Label 18 points to the camera's shutter. The cloth curtain opens for a fraction of second allowing light to pass through and expose the film. On a digital camera, the shutter allows light to come into contact with a digital sensor array.

The longer the shutter is open, the more light is allowed to pass through. A very slow shutter speed is 1/8th of a second. In contrast, a fast shutter speed is 1/1000th of a second.

The side-effect of low shutter speeds is that objects in motion may become blurred. This can be used to good effect, when one wants to convey the sense of motion. Or, the blurriness may detract from the final image.

On both traditional and digital cameras, the aperture is the lens opening that controls the amount of light that passes through the lens onto the film or digital sensor array.

The aperture is like our eye pupil.

The wider the aperture, the more light is allowed to pass through. A very wide aperture setting is f2.8. In contrast, a very small aperture setting is f16.

The side-effect of wide aperture settings is that the range of objects that appear in focus becomes narrower. The subject that the camera is focused on will always be in focus, but objects ahead of and behind the subject get more blurry. This is called the depth of field.

The camera is focused on the first peg. The second peg is already blurry and the third peg is blurrier. This photograph was shot with with a low aperture setting like f4 or f2.8.

Had the photographer shot with an aperture setting of f16, the depth of field would have been wider. The second and third peg would have been more in focus.

So given that a wider aperture (lower setting) lets in more light but reduces the depth of field and given that long exposure time lets in more light but causes more blur,

try to recreate the photograph to the right.

On the next page, choose the settings that you anticipate will recreate the photograph of the flower.

In each case to maintain the same exposure or the same amount of light hitting the film, you need to balance aperture opening with shutter speed. The higher the shutter speed, the wider the aperture. The smaller the aperture, the longer the shutter speed. They always balance one another.

So go ahead, turn the page and pick the correct aperture setting and shutter speed.

In the flower photograph, the flower was in focus but the background was not.

Therefore the correct answer to the question involves a smaller number, which represents a larger aperture.

The basic idea behind depth of field is that wide apertures (small number) mean less in focus and small apertures (big number) mean more in focus.

A setting of f2.8 means a wide aperture. Less in focus. A setting of f16 means a smaller aperture. More in focus.

Turn the page.

Let's examine some photographs with small aperture settings.

Turn the pages to view the different photographs.

Notice the background. It is entirely blurred.

The long telephoto lens also helped to reduce the depth of field.

Canada Goose coming in for a landing.

Aperture f/5.6

Shutter speed 1/200 of a second

Aperture f/5.6

Shutter speed 1/250 of a second

The photograph of Columbine to the right was shot at f5.6 at 1/30th of a second.

Let's view some photographs taken with a f2.8 aperture setting, and then we'll display some photos taken with a f5.6 setting.

Turn the page.

Now contrast this photo with the following photos taken at f5.6.

The depth of field in a close-up shot may be restricted to a few inches. The depth of field in a medium range shot may be a number of feet.

In either case, the depth of field in a picture shot at f5.6 is greater than one shot at f2.8 and less than one shot at f16.

The f2.8 setting greatly reduces the depth of field.

The flower in our photograph was sharply focused and the background was quite blurry.