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Depth of Field

1st Assignment

Your first assignment involves "Depth of Field".

Test the Simulated Camera and Read the Link Above Regarding "Aperture and Depth of Field" along with the information below before heading out to take photographs.

Materials Needed:

  1. 100 ASA/ISO Film

  2. Lighting Chart (In your Photo I Handout)

  3. Objects or Subjects for photographing.

  4. Pen, Paper or Notebook to Log Aperture, Shutter and Lighting Conditions

Steps to be taken:

  1. Set up your shot

  2. TAKE ALL SHOTS FROM THE SAME SPOT - DO NOT MOVE ANYTHING EXCEPT YOUR F-STOPS!

  3. Read Lighting Chart to Determine lighting conditions to set F-stop and shutter speed for the "perfect shot"

  4. Take 1 shot with the "perfect settings"

  5. Take another 2 shots moving the f-stop down two stops

  6. Take another 2 shots moving the f-stop up two stops

  7. You should have now taken 5 images of the same subject

  8. Use other subjects, and following the same steps as 1-7, take 5 more images of these new subjects or objects.

Use the rest of your film, experimenting with f-stops to change the depth of field.  Remember to use your Lighting Chart for each and every shot!  Don't guess!

 

Controlling Depth of Field

Let's take a look at some real examples of how aperture settings affect depth of field. In the example shown in Figure 2.9 , the lens is set to f/2.8, which gives a narrow depth of field but fast shutter speed.

Figure 2.9. This image was captured at f/2.8 with a very shallow depth of field.


Using Aperture Settings

 

Moving the aperture setting to f/8, or three stops, puts more of the image in focus (Figure 2.10) . A setting in this range is a good compromise between depth of field and shutter speed, especially when there is movement in the image.

Figure 2.10. By adjusting the aperture to f/8, more of the image is in focus.


Using Aperture Settings

Finally, by using an aperture setting of f/22, an additional three stops, we've maximized the depth of field to get as much of the image in focus as possible (Figure 2.11) , but must now accept a very slow shutter speed to accommodate such a small aperture. This is also ideal for a landscape image where you have detail in the foreground and in the distance that are both important to the image.

Figure 2.11. An aperture of f/22 maximizes the area that is in sharp focus.


Using Aperture Settings

http://cubox.info/2007/10/22/using-aperture-settings.html

 

Understanding Depth-of-Field

http://www.nikonians.org/html/resources/guides/understanding_dof/

Depth-of-field (DOF) is one of those things that can confuse a lot of new camera users. Yet, it is very important!

Choosing the right combination of apertures and shutter speeds is initially hard to comprehend. This article is written to help you understand those relationships to help you control your image's look, while maintaining correct exposure.

I'm going to attempt to explain these concepts with pictures.

Lets say you are taking a picture of a friend, who is standing 2 meters (~6.6 feet) away from you. About 2 meters behind your friend is another person. There is also a third person standing about 2 meters behind the second person. Three people total — each about 2 meters apart — with your friend in front.

You are shooting with a 50mm lens. You focus on your red-shirted friend's face, and take a picture. It looks like this:

50mm lens, Aperture: f/1.8, Shutter Speed: 1/6000th of a second

Notice in the picture above that your friend (in red) is in good focus. The girl standing behind her, to the right, is not in focus, nor is the young lad even farther away to the left. This is the result of shooting with a big "aperture." The f/1.8 is a big opening in the front of your lens. It also causes the depth-of-field, or "zone of sharp focus" to be shallow.

Only the girl in front is in focus at f/1.8. Not much else is in focus, so there is very little depth-of-field. The depth-of-field in this picture is well less than one meter. Probably more like 1/2 meter. (~1.5 feet) The zone of sharp focus is therefore only about 1/2 meter deep.

The f/1.8 is an "aperture" number. An aperture is simply an opening in the front of your lens controlled by blades. If you divide the focal length of the lens into its aperture f-number you get the diameter size of the effective aperture in the lens. In most cameras you should see the f/number somewhere in your viewfinder display but you won't actually see the effects of your aperture setting. This is because your auto single lens reflex (SLR) camera with an auto lens allows you to focus with the aperture blades wide open and out of the way. The aperture closes down to its selected setting when you press the shutter release to take your picture.

Apertures on a typical zoom lens start at about f/3.5 (big aperture), and go to f/22 (small aperture). The bigger the actual size of the aperture can get (the larger the opening) the "faster" the lens is considered. When you hear about a "fast" lens, someone is talking about a lens with a big maximum aperture opening. The 50mm f/1.8 lens I used for our example photos is definitely considered fast!

So what would happen if we closed the aperture down (also referred to as stopped down") to a medium-small aperture like f/8? The picture below shows what that will do to the depth-of-field:

50mm lens, Aperture: f/8, Shutter Speed: 1/500th of a second

Notice how the girl in front still looks sharp, and the girl to the right is now in focus too. You still focused your camera on the girl in front but now the girl to the right is sharp too (even though you did not change your focus point).

The depth-of-field, or zone of sharp focus, now extends past the girl in front and covers the girl in back. But, also notice that the boy to the left is still not in focus. The background is not in focus either. This image is the result of a medium aperture opening (f/8), not fast (f/1.8), or slow (f/22). Now let's consider what happens if we "stop down" or close the aperture to f/22:

50mm lens, Aperture: f/22, Shutter Speed: 1/40th of a second

Aha! Now everything in the picture is sharp. The smaller f/22 aperture makes it easier to get sharp focus. Remember, you focused on the front girl's face in all these pictures. At first only she was in focus (f/1.8), and as the aperture got smaller more and more of her surroundings came into sharp focus (f/8 and f/22).

So, Depth-of-Field is simply the zone of sharp focus. It extends in front of and behind your focused subject, and gets deeper in both directions as you “stop down” your lens. If you set your camera to A mode, or Aperture Priority, you can adjust this powerful functionality to control what is in focus in your pictures.

 

More Understanding of Depth of Field

http://www.photoaxe.com/examples-for-understanding-depth-of-field/

 

  

Shallow depth of field for example, can be used to focus more attention on a  foreground subject, by blurring out the background. (This can be useful in portraits amongst other things.)

In this very successful photograph, the only area that is in focus is immediately close to the inside of the watch. Both the model in the background and the cover of the watch in front are very blurry.

In this photo the depth of field is very shallow, just a few centimeters long (less than an inch).

 

Below is a series of photographs of the same subject that were taken with different apertures. This will show you the difference in depth of field that happens as a result of using different apertures, as opposed to just reading about it.
dof
F/1.4
dof
F/5.6
dof
F/16
However, don’t forget that Depth of field is influenced by three main factors: 1) Aperture, 2) Focal length, and 3) the distance to the subject.

 

 

 

 

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