Null objects are essentially dummy layers. Null objects come in really handy when you're working with expressions, parenting layers, or working in 3d space. When working in 3d space, if you parent something to a Null, it carries over 4 properties:

•Position
•Anchor Point
•Rotation
•Scale

Because it carries anchor point over, it gives us a good bit of control with 3d. There definitely is not as much control available versus animating cameras, but we can still do some  pretty cool stuff.

For instance, I can move this seen around by simple selecting the orbit tool. It moves my scene around a little bit, but the movement isn't as natural as I want it and it's harder to get exactly where I want it to go.

An alternative to selecting the orbit tool and constantly tweaking the keyframes to achieve the result you want, lets create a Null Object and see how that works.

I'm going to go ahead and turn off my camera and right click in the blank area around  between the layer name and number. Select New>Null Object.



Also, be sure to remember that null objects work regardless if their visibility is on or off. Turning the visibility off will turn your gizmos visibility off but the null object will still be there working like normal. You may want to turn off the visibility if the gizmo is getting in your way for some reason.

Go ahead and make the null 3d.

Select the first layer, then shift+click the last layer. Then pickwhip one of the layers to parent them to the Null (Since they are all selected, they will all be parented.)

Now, when I reveal my rotation properties of my Null Object Layer (R) and adjust the parameters, a much more controlled movement is achieved throughout the scene. Everything is spinning around the one anchor point of the null object so everything looks more uniformed and smooth.

Again, nulls do not give us nearly as much control as cameras do. They just can't do things that cameras can do, but they do provide a quick solution to basic animations in 3d.