Will Head
Obviously, it’s always a good idea to set out to capture great footage from the start of any project, but sometimes the subject matter may limit your abilities somewhat or you may have to work with footage that someone else has shot, which can be even worse. Even if you have fantastic footage to start with, some projects deserve the highest production values.
You obviously have a huge number of built‑in effects and transitions at your disposal, but if you want to make the most of what your editor has to offer, you’ll need to understand the power of key frames.
Key frames essentially take a huge amount manual work out of the process of animating elements on screen. Without them, if you wanted to move an item from one side of the screen to the other, you’d need to start at the first frame and then move it slightly in every subsequent frame until the last frame. Given that video runs at 25 frames per second, the number of manual changes you may need to make will soon add up. Just to move something across 30 seconds of footage, for example, would require 750 manual adjustments.
The beauty of using key frames, however, is that you can just specify the start and end points, and let your editing program work out where the object should be in between those points. It turns a hugely laborious process into a two-click operation.
Key frames also provide a great deal of flexibility to experiment. If you have to manually alter every single frame and you’re not happy with the final result, you’ll need to spend as much time again changing it to something else. Using key frames, you have only got a couple of things to change, so you can try things out more until you find the effect that works.
The real power of key frames comes from the fact that almost everything in your editing program can be key framed. Anything you use to modify video in some way – for example, scale, rotate, colour, opacity, blur – can be key framed, so that instead of just altering the video once, the effect changes over time. Add in the fact that you can apply multiple key frame effects, running at the same time to the same clip, and you have hugely powerful capabilities to make your video project look more visually appealing.
Applying key frame effects to your clips in Final Cut is simple. Start by dropping an effect onto a clip on the timeline, such as Light Rays from the Glow folder in the Effects browser. If you then double-click on the clip on the timeline to load it into the Viewer window, you can select the Filters tab to see the effect properties. There are various parameters you can adjust on the Light Rays effect to get the look you want. However, more importantly with key frames, you can also adjust these properties over time.
The Amount property, for example, specifies how extreme the effect is; it defaults to 50 but ranges from 0 to 200. You can use the slider to adjust the value or type in a specific number in the box next to the slider. To the right of the amount box is the round key frame button; just click this to create a new key frame. Creating a single key frame will have no effect on the output, as it only defines one of the points necessary and you need another to actually create an effect.
To the right of the key frame button you’ll see another timeline with a green horizontal line. This line represents the value of the parameter you have adjusted. For example, the Amount property ranges from 0 to 200. Decrease it to 0 and the green line sinks to the bottom, increase it to 200 and it will rise to the top.
To create a second key frame, move the playhead to somewhere else in your clip and adjust the Amount property again. When creating a second key frame, you don’t have to press the key frame button, as Final Cut will automatically create the key frame for you since you have adjusted a value that already has a key frame applied to is.
If you look at the green line now, you’ll see that it’s no longer straight: there’s a diagonal section between the two key frames you have created. This line represents the effect you have just created. You can continue to create further key frames by moving the playhead and adjusting the Amount value again. Each time, you’ll see the change reflected in the green line and a new key frame will be created at each point.
If you want to adjust where in the clip your key frames occur, drag them backwards or forwards on the green timeline to change the timing. If you want to adjust the parameter attached to a specific key frame, you can click it on the green timeline and change the value. However, you have to be careful and ensure you have the key frame selected, otherwise you’ll create another new one next to the one you were trying to adjust. This is because Final Cut creates a key frame whenever you adjust a parameter on a clip that has one or more key frames already defined.
If you’re not careful, you could end up with lots of key frames close together and a completely unpredictable effect. One way to avoid creating excess key frames is to use the key frame navigation buttons. To the left and right of the create key frame button are arrows that navigate to the previous or next key frame. Just click in the direction you want to go and you can be sure you have got a key frame selected before adjusting its value.
So far, we have only applied key frames to the Amount parameter. However, the Center, Glow, Expansion and Mix parameters can also be key framed independently of each other. As you can see, this gives you a huge amount of power over a single effect.
By default, the green line between key frames is a straight diagonal transition, but if you find the effect too harsh, you can turn it into a curve. Just Ctrl-click on a key frame and choose Smooth from the context menu. You’ll then see two Bézier handles that let you even out the transition and create a smooth curve.
In addition to key framing effects applied to a clip, you can key frame the position and scale of the actual video clip, too. With the clip still loaded in the Viewer, click on the Motion tab. You’ll see the same key frame controls and green timeline as before. Use the same technique to adjust where the video frame is over time to animate it across the screen as it plays.
As you can see, key framing is a skill that provides endless creativity when it comes to making interesting video. It obviously needs to be used sparingly and in appropriate situations, but when applied correctly, it can greatly improve the final production.
