A lot has been made of the improvements to the Speed feature in Final Cut Pro 7. Yes it has better control over ramping, but does it render a better result? If you want the video to slow down, then the answer is no. The new FCP 7 is no better than version 6. It will only double frames or blend frames together in a really haphazard way. To create a realistic slow down effect, you need to create new frames in between the existing frames. This is called interpolation. The best software for doing this is ReVisionFX Twixtor. It’s available for FCP as a plug-in. It’s also available for After Effects, Premiere Pro and a bunch of others. The following example was made using the standard 4.5 version of the plug-in, at the default settings. The video is below, but you should watch it in 720p on Vimeo to really see the difference.
Footage from The World Heli Challenge, courtesy of MarniProductions.com
I also use Twixtor to change frame rates in the case of the 30p output of the Canon 5D (30p to 23.98), and to convert in and out of PAL, which is 25fps. For this feature, you need the After Effects version. This method could also be applied to my 60i to 60p to 24p tutorial. You could skip all the steps I outline in that tutorial and just apply Twixtor to your clip in Final Cut Pro, and set Speed to 40%. If you select another percentage, Twixtor will interpolate the new frames you need. Twixtor also allows you to keyframe the speed setting, so it will do any ramp effects you need with a much higher quality result than FCP’s built-in Speed feature.
Twixtor is available from RE:Vision Effects
Edit: I have only recently noticed this. Twixtor 4.5 for Final Cut Pro comes in 2 flavors, one is a version that is also compatible with After Effects (this is the one I have) and one that is an FxPlug plug-in that only works in FCP. I got the first one because I wanted to do things in After Effects that only work there, such as frame rate conversions. But the AE-compatible version will only work on 8-bit material in Final Cut. So if you are working in ProRes, which is 10-bit, this plug-in won’t work. If you own only one of these versions, you can buy the other from RE:Vision Effects for only $99.