This is more of a video skill question, but I wasn't sure where to ask. I want to do a shoot where you have some stuff going on in the background and some in the foreground. The shot is focused on the background and you don't really see the foreground, Then the camera seems to move backwards towards the foreground and the focus changes to the foreground.
Does anyone know how to do this or can suggest where I can find some how to's?
I think you're referring to a "Rack Focus", do a search for it. Unless you're talking about the trick where someone is standing in a hallway and the hallway appears to suddenly get longer in the background. I recall reading once how that works, but it eludes me right now.
Shooting a rack focus shot requires detailed control of depth of field and careful operation of the focus control on your camera. Not knowing if you're using a pro camera or a consumer one, you might have some trouble pulling it off.
That said, you can fake that kind of rack focus by shooting your foreground item as a separate element and compositing it on your background. Apply a fast or gaussian blur to the foreground element, and then when you want the rack to happen, keyframe the blur down to zero on the foreground element while keyframing from zero to whatever looks right for the background. If your composite is clean, this works really well.
The power zoom or power rack, as I've heard it called (making the hall look longer) is tricky, but looks cool when done right. It's a combination of dolly in and zoom out at the same time. You just need to be able to get the timing right with the camera move and the lens zoom.
Hope that helped!
Thanks for reading!
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