3 Replies Latest reply on Nov 15, 2014 1:48 AM by Rick Gerard

    Film size measurement

    Arivl Level 1

      Hey folks, quick question:   for the "Film Size" setting in Camera Settings, what dimension of the film plane does it measure?  Vertical, Horizontal, or Diagonal?  I'm assuming vertical since the camera diagram shows reels on top, but I wanted to make sure, as it can be important.


      Assuming it was measuring the vertical axis, Super 35mm would be 18.66mm?

        • 1. Re: Film size measurement
          Arivl Level 1

          Anybody?   It's actually more confusing than I originally thought.  The white camera diagram suggests that it's measuring the vertical axis, but when you view the numbers in pixels, the "Comp Size suggests that it's actually the horizontal axis!  (This is a 1920x1080 comp for a test).

          Screen Shot 2014-11-14 at 3.54.55 PM.jpg

          • 2. Re: Film size measurement
            Dave LaRonde Level 6

            Are you concerned the camera will cut off at the edges of your comp?  Don't be: it'll be fine.

            • 3. Re: Film size measurement
              Rick Gerard Adobe Community Professional & MVP

              The graphic is a little misleading because the indication is that the measurement for film size is vertical when it is actually horizontal. If you change the units to mm then you have something you can compare to a real camera. The default is based on a full frame 24mm X 36mm frame or standard 35mm camera like a Nikon SLR.  I would rather have the default camera be a 35mm cine camera because I've been using them for 40 years and know without looking at any charts or tables what kind of depth of field I'll get and what kind of shot I'll get when I put the camera 4' from an actor with 40mm lens and set the aperture at t-2.3


              The angle of view is also measured horizontally even through the graphic indicates that it is measured vertically. For example, if you look at a lens chart for a 50mm lens on a full frame 35mm camera you will see that the horizontal angle of view is 39.6º. This lets you set your AE camera to the same focal length of a full frame 35mm camera and then match perspective. If you wanted to match film shot on 35mm cine camera then you would change the film size to 22mm because that is standard 35mm academy aperture width. It works for all 35mm film cameras including super 35 (3 perf) and techniscope (2 perf) so as long as you're not shooting anamorphic, you could, if you wanted to, match focal length.


              Here's the deal in the real AE production world. If you want to match perspective and you have a moving camera just use AE's camera tracker and AE will automatically calculate the field of view and position the camera so perspective matches. If you do not have a moving camera, then you must either know the sensor size of the camera used and the focal length of the lens or the angle of view. If you do not know what these values are then you'll have to guess. (See the next paragraph.)  You must match camera position if you are going to match perspective. The biggest misconception about lenses is that focal length changes perspective. Perspective is controlled by camera position and not focal length. Focal length just controls the framing. Long lenses crop tighter, wide lenses crop wider. If the camera does not move the perspective does not change. Lenses may distort, and wide lenses have a tendency to distort more than telephoto or long lenses. AE's camera is perfect so if you are trying to match a real wide angle lens that has a pronounced distortion you'll have to add a lens distortion filter to your project to match the distortion or apply lens compensation calculations to the footage to remove the distortion (the preferred method), and then, if you want, add in lens distortion after everything else is done.


              So here's how to match perspective if you didn't take any measurements on the set and you have to guess. Add a camera to your scene and a big 3D layer (about 4X comp size) with grid applied so you have something to line up. pay attention to where the horizon is and compare that to the center of the screen. The distance from the horizon to the center of the screen will give you an idea of the angle of tilt. If you move the solid layer's anchor point to the horizon line and then rotate the layer 90º you can then start moving the camera up or down until your grid starts to match the ground plane. This is assuming a 2 node camera with the point of interest at comp center. When you get the grid close to matching the ground plane then you start moving the camera closer or farther away  until the perspective lines match up. Once the perspective lines match up you can adjust the focal length (zoom value) of the camera to frame up the grid so that things look right. When you have a match your AE camera's perspective will match the perspective of the camera used to shoot the shot. All that is left is to make some educated guesses at aperture to get the depth of field to match up.


              Hope that helps. The camera will always record the full frame of the comp, the other settings just help you frame things up.