Now we need to create the connections between the distance tool and the camera DOF settings.

From the outliner select the "distanceDimensionShape1" node and then CTRL (Cmd on Apple) click the "CameraShape1" node. Select Window>General Editors>Connection Editor to open the connection editor. You will see that the output pane has all the attributes from the distance tool and the input pane has all the attributes from the camera.

Scroll down in the outputs (left) pane until you find the "Distance" attribute. It should be right at the bottom. Click the attribute to select it. Now scroll down in the inputs (right) pane until you fine "Focal Distance". Be careful not to select "Focal Length". This is a completely different attribute. Again, simply select the attribute to create the connection.



You can now close the connection editor and we can now do some clean up.

Rename "locator1" to "cameraLocator". Rename "locator2" to "aimLocator". Now select both locators and the "distanceDimension1" node and place it all inside "camera_group1". Now select the "cameraLocator" and hit CTRL-H (Cmd-H on Apple) to hide it. Do the same for "aimLocator". If you really want to be sticky, you can also select all the attributes from the two locators and lock and hide them. You can also hide the distance tool, but I like to keep it visible.

Thats it. All you need to do now is turn DOF on. Select the "camera1Shape" node and open the attribute editor. Scroll down until you find the "Depth of Field" section and turn on the check box.

Now you have a camera that will update its own focal distance depending on where you place the "camera1_aim" locator.

Nice and simple, but rather effective.