This is the sixth of a semi-regular series of columns I’ll be presenting on how to do some basic special effects, for people who have little to no experience. We use these effects quite frequently in our Harry Potter-based web series The Spell Tutor.
In this column I’m going to talk about manipulating time in your edits, which can be used to do various tricks. The first thing you need to do is take a moment to figure out how to change the playback speed of clips in your particular editor.
You won’t be able to do standard slow-motion sequences properly unless you have access to a camera that can shoot at high frame rates (120 frames per second or higher). But you can do a lot with regular frame rate footage by speeding it up.
For this scene in The Spell Tutor, the actress was directed to jump out of frame to the side to simulate being hit by a spell. During post-production, when the visual effects were added, it didn’t look quite convincing enough, so we sped up the footage starting at the moment she started her jump, up to 300% of normal speed. This quick acceleration improved the scene and gave it the needed feeling of impact.
You can see this technique in Star Wars: A New Hope as well. On board the Death Star, there are several instances where the playback rate is accelerated to make doors open and close rapidly. (You’ll also notice the actors doing their best to remain still during these shots.)
For another sequence, we wanted to imply a quick transition as the girls are apparated to another location by the Myrmex Leader. We mounted the camera on a dolly and rolled it towards the actors for the first phase of the shot. Later at an outdoor location, we started the camera at a tight zoom on the girls and pulled back to a medium shot. Then we turned up the playback speed for this result.
Another nice trick is to reverse playback direction. On a music video I did once, I needed the camera to move in and end up centred on the right eye of the lead actress, so we started off tightly framed on the eye and pulled back. Then we simply reversed the clip to get exactly what we needed. This trick works with any moving shot that requires hitting a difficult target.
I’ll close off this column with an experimental use of time manipulation I did for a music video a while back. Enjoy!
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