5 Replies Latest reply on Aug 26, 2016 4:53 PM by buck9

    Dolly zoom with green screen in background

    buck9

      I'm preparing to do a shoot with my subject resting on a table top with a green screen directly behind. I recently decided I wanted to do a dolly in, zoom out but realized I might have a problem trying to achieve that vertigo effect with a green screen and no actual image during the shot. Is it as simple as shooting the dolly zoom and then placing the image in later? Any help would be very appreciated.

        • 1. Re: Dolly zoom with green screen in background
          Mylenium Most Valuable Participant

          Could be, could be not. Eitehr way, put some markers on the screen as reference to avoid that floaty look if your inserted BG doesn't line up 100%.

           

          Mylenium

          • 2. Re: Dolly zoom with green screen in background
            buck9 Level 1

            Thanks, shot the footage and will start playing with after effects in a few days. Will give an update with my results

            • 3. Re: Dolly zoom with green screen in background
              buck9 Level 1

              After placing my background image on the green screen there is no vertigo effect taking place. I suppose you could cheat the effect by dollying into your subject (no zooming required)) and then shooting your background image making sure to slowly zoom in or out, depending on which way you dolly in your previous shot. Have my doubts about how well that could look though.

              • 4. Re: Dolly zoom with green screen in background
                Rick Gerard Adobe Community Professional & MVP

                The Alford Hitchcock vertigo effect is created by placing an actor in the foreground and then moving the camera towards the actor while you zoom out to keep the actor the same size in the frame.  Perspective is controlled by camera position so as the camera moves toward the actor the relationship between the actor and the background changes. You get all kinds of natural parallax shifts that your eye expects. When you zoom while you move your brain does not expect the framing to remain constant as the perspective shifts. This gives you the dizzying vertigo effect.

                 

                I'm telling you all of that because if you want to pull this off using a green screen you will have to shoot a background plate with the same or nearly the same timing as you shoot the green screen shot.  Let's say you push in on the dolly for four seconds and move 10 feet. During that four second dolly you zoom from 70 mm to 24 mm. To make the effect work you will need to pick something for a background plate that has enough geometry in the shot to give you  perspective and parallax shifts, and position the camera approximately the same distance from your nonexistent actor as he would be if he were in the scene. You then do the same 4 second 10 foot and 70 to 24mm zoom you did in the studio to make the shot work. Just use a still image  or a locked off camera shot as a background plate you will not get the strong "vertigo" effect that you would get shooting the shot for reel.  I discovered this the hard way when I shot a film about 15 years ago that needed a half a dozen vertigo effect shots. I had to reshooting the background plates about four times before we finally got it to work. All of the other attempts just looked weird.

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                • 5. Re: Dolly zoom with green screen in background
                  buck9 Level 1

                  Thanks for your response, very informative . Fairly new to all this and trying to learn as quickly as I can. Decided to scrap the shot but I'm sure I'll give it another go at some point.