In addition to setting a value we can actually animate our focal distance. At the beginning of our composition we want the focus to start on number 5. So I will click on the stopwatch to set a keyframe, then modify the value for the focal distance. I know that number 5 is +600 pixels on the Z axis. I know that there is also an additional 600 pixels between 0 and the camera.

So I need to add those two together in order to get my focal distance for octopus number 5. By merely changing the focal distance I change what the camera perceives as in focus.

Now I can change the Depth of Field values for this camera even further using Aperture or F-Stop . Now these two are linked together and depending on which one you are comfortable with, you may need to open up the Camera Preference Window in order to change them. If you are familiar with Aperture setting you can set that here by simply clicking on the value to change it or scrubbing it. We will change our Aperture here to a value of 28.

Now if you are more familiar with F-Stop you may want to change it using the dialog box. So instead of changing the Aperture here let's double-click on the layer for the camera and bring up our Camera Settings.

Here we can see there is a dialog box for both Aperture and F-Stop, but because they are both linked, so by changing the Aperture value we can see that the F-Stop has been updated through reflected difference in their relationship. If you prefer to work in a value other than pixels you can do that by changing the Units value here from pixels to inches or probably millimeters.

Now when using millimeters you can see that all of different values update in the dialog box. However although we are using millimeters to get an Aperture value of 4.9, once we click OK you can see that the Aperture value set inside our Timeline is now 14, and the reason for this that the Timeline uses values defined by pixels. We will click here and change this again to 28 pixels. Once we change the Aperture to 28 pixels we can see that the Blur becomes much more apparent as the layers move away from the focal distance.

The last thing we want to do for focal distance is animate it. At the beginning of the composition we will start with number 5 being in focus, but then closer to the end of the composition, we want number 1 to come into focus. Now I don't want to set it exactly in front of layer 1 but just a little bit beyond it so that it still keeps a little bit of depth there.

So rather than changing this to simply 400 pixels, I will change this to a value of 450. the reason for this we are working with a layer whose Z position is about -200. The distance between -200 which is this layer and -600 which is the camera's layer is about 400 pixels which is going to be our focal distance.

Now with this key set here, if we scrub back in time, we can see the focal distance animating overtime. The last thing we will do is set for the last key-frame on this focal distance by holding down the Shift key and pressing F9.

Additionally there is one more layer that I want to turn on which is the background and turn it on then, with the quick preview we can see how animating the camera and all of the different properties of the camera will give us not only a 3D composition but a very dynamic 3D animation.