The light writing effect
 

Its become quite popular and overused in the last year or so.
And that is when a person in a commercial seems to write with a pen light and the light stays on screen even when the character leaves.

Well one the client I'm working with asked if I could do it. I simply told him I'd look into it. I'm somewhat against it mainly because it's quite overused at the moment, but I will look into it for him.

So whats the deal with this effect? is it mostly done in production or in post. I would assume in post, likely in AE or Shake.

Has anyone done this trick? if so how?

Im not sure if this method is how its normally done, but there is a tutorial on videocopilot.com that deals with light streaks in AE. Its pretty simple and Im sure could easily be modified to do exactly what you want.

There are probably easier ways however, so hopefully some others chime in! :)

I'd LOVE to know how they did it before post production. Are you talking about the iPod effect (videocopilot.net), or just the light kinda like that stop animation-esque ad where they're drawing stuff in the park (like the fish that jum,ps out of the concrete)? My question is how they make it look so good with camera movement.

takes alot of work/time. isn't a simple drag n' drop plugin. andrew kramers tuts are really good so i suggest checking those out, and he shows how to motion track footage when the camera is moving.

Well I figured it wasn't an easy drag and drop, nothing usually is. Kramers tutorial is a great start, I've gone through it a few times and am getting the jist of it.