Lesson 2

In the last lesson, we talked about the technical side of focus. Today we’ll talk about the creative side or the Depth of Field.

In a shallow or narrow depth of field, part of the image is in focus (the subject) the rest is out of focus.

Greater depth of field is just the opposite. As in the image below, everything is in focus.

You can see good examples of shallow depth of field in Dan’s pictures of the yellow flowers and the pick roses and in several of Diana’s pictures. If you look through everyone’s original “10 Favorites” you’ll see many other examples.

All of the images that you have submitted could have shown everything completely in focus, but someone chose (or the camera chose) to create a shallow depth of field.

So, how do you achieve this beautiful selective focus? There are several contributing factors:

The aperture
The distance from the subject to the background
The focal length of the lens

In order to continue, we need to talk a little about exposure. In our first lesson I said that in an exceptional image, the subject had to be properly focused and properly exposed – meaning the right amount of light on the subject. The subject is not too light and not too dark.

The camera controls the amount of light given an image by two things, the aperture (opening) of the lens – 1) the more open the aperture is, the more light it lets in. The more closed, the less light – just as your would expect.

And 2) how long the shutter keeps the lens open (called the shutter speed). Again it’s obvious: the longer the shutter stays open, the more light on the image. Aperture and shutter speed always work together to accurately (or inaccurately) expose your image.

There are usually several combinations of aperture and shutter speed that you can use for any give image and still have a properly exposed picture - a wide open aperture and a fast shutter speed or a smaller aperture and a slower shutter speed, and a few combinations in between. The only difference in the final picture is the depth of field.

If your camera has an aperture priority option, that is what you will be using this week. If it doesn’t, the camera manufacturers have preset the camera to shoot with the aperture either all the way open - portrait mode, and closed down - landscape mode.

Assignment:
Check your manual and
1. find out if your camera has an aperture and shutter speed option. It may be labeled Av and Tv.
2. see if you have an optical zoom or a digital zoom or both
3. post your findings

4a. If you have an aperture priority option, take 20 -25 pictures with the aperture fully open (f 2.8 for example. The smaller the number, the more open the lens). Then take the same basic image with the smallest aperture that light conditions will allow (f11 for example. The larger the number the more closed down the lens.) You will have problems achieving a properly exposed image if you try to use a small aperture in low light conditions – there just won’t be enough light, even at a slow shutter speed. So you may want to perform this assignment outside (during the day J) Then take the same images in auto mode. Post some of your results.

4b. If you do not have an aperture priority option, take 20 -25 pictures in portrait mode. Then take the same basic image in landscape mode. You will have problems achieving a properly exposed image if you try to use landscape mode in low light conditions – there just won’t be enough light, even at a slow shutter speed. So you may want to perform this assignment outside (during the day :)) Then take the same images in auto mode. Post some of your results.

Next time we'll talk about the effect the focal length has on the image.