This article will go into the details step by step of a camera control I originally showed in my 'Understanding Motion's Camera Controls, Part 1' article.
It can be very useful with photo montages, showing a large product line, and for titles. Once you see how it works, let your imagination go wild.
I'll open a generic Motion template, 5 seconds long, 720p30. Shift-Z to fit the canvas to my window size. Then hit R for the rectangle drawing tool. Hold the Shift key while dragging to create a perfect square, and hit the Esc key to get out of the shape edit mode. F4 activates my Inspector so I can turn on the Outline, make it red, and increase it to 20 points wide. Finally, I'll go to the Object menu, select New Camera, and tell Motion to make my layers 3D when prompted.
Now to create a whole row of squares to fly past our camera. Select the Rectangle layer and hit the L key. In the Inspector we will change the Shape to Line, and set Points to be 10. Check the 3D box. For Start Point and End Point, click the disclosure arrows to show X, Y and Z parameters. Set them all to zero, except for Ent Point Z, which should be -20,000.
To see how this is working, use Control-P to get into the camera's Perspective mode, then click and drag right on the middle button of the view controls at the top right of the Canvas.
Make the squares fly past the camera by verifying the Replicator layer is selected. F1 activates the Properties tab in the Inspector. With the playhead at the start of the timeline, click the Keyframe diamond to the right of the Position parameter. Click its disclosure triangle to show the X, Y and Z parameters together. Make sure all three are set to zero.
Move the playhead to the end of the timeline. Set the Z parameter to 20,000. Now if you play through the timeline, you'll see the squares moving from far away, towards, the through the camera.
Here is where we get to the heart of things. Before going further, please refer back to the article mentioned previously, and read the 'Step 4 - Planes' and 'Step 5 - Fades' sections.
With the Camera layer selected, use Control-A to set the camera to the Active Camera mode, use F4 to get to the Camera Inspector. You can also start playback to watch what is happening in real time. First set the Near Plane to 500. This makes the squares disappear when they are 500 pixels away from the camera. We don't want them piping, but fading, so set the Near Fade to 1500 pixels. This makes them start to fade when 1500 pixels away, before disappearing at 500 pixels.
So that you can actually see the fade in, with the Camera layer selected, F1 for the Properties Inspector. In the Rotate controls, set X to -12. Now F4 back to the Camera controls, and set the Far Plane to 3000. Now the square will be invisible until it gets at least 5000 pixels from the camera. To make them fade in, rather than pop in, set the Far Fade to 1500 (or 2000, depending on taste).
What you should be seeing is squares fading quickly in, then fading quickly out. Without setting the Plane and Fade controls, you'd see squares coming at you from very, very far away. You'd actually see them back into infinity, virtually. Then you'd see them hit the camera and go back behind you. This way, we have a fade in and fade out effect. You can use the Plane and Fade controls independently of each other, and also use the Near and Far controls independently of each other. To take this one step further, you could also use an image sequence (simply a folder of images named in numeric order) as your replicator. Have fun with this, and let us know what you're creating with such an easy and interesting technique.