7 Replies Latest reply on Nov 19, 2008 2:34 AM by Jonas Hummelstrand

    Slow motion question


      I'm trying to make some really slow motion. I shot an object falling down using a shutter of 1/2000. The camera was canon hv20 and the footage is hdv 1080 25p.

      I brought the clip in to After Effects and tried both time remapping and time strech to slow the clip down at least 400%. Here's the problem: the slow motion is very jerky. The falling object goes down in very visible steps. What seems to happen is AE simply duplicates the frames to make the footage last longer, but this does not look good because it means that the object will stay in the same position for several frames. I was hoping that I could get intermediate frames in between the two original frames, in other words a smooth transition between the original frames. Now there is no transition at all, the object stays in one position for many frames and then drops to another position and stays in that for many frames.

      I tried to change the frame blending to both pixel motion and frame mix but I still don't get mixed frames, only duplicated ones. Am I doing something wrong? Is the thing I'm looking for even possible?

      Any help will be appreciated greatly!
        • 1. Re: Slow motion question
          Jonas Hummelstrand Level 2
          Look here first:
          i http://help.adobe.com/en_US/AfterEffects/9.0/WS3878526689cb91655866c1103906c6dea-7d58a.ht ml
          • 2. Re: Slow motion question
            bogiesan-gyyClL Level 3
            > The camera was canon hv20 and the footage is hdv 1080 25p. <<br />
            Jonas was being characteristically kind. Slow motion has been around for more than 100 years. You could have researched this easily before planning your session.

            The only ways you can create smooth slow motion is to have more discrete slices of time or use very expensive software to fake it for you by recreating every pixel of every frame to compenstae for the frames you failed to shoot. the term expensive is used to describe third party tools from the likes of ReVision or the time required to use Apple's SmoothCam Optical Flow or a similar product from Adobe.

            • 3. Re: Slow motion question
              Level 1
              Thank you for your responses. I thought pixel motion and frame mix were options for achieving better slow/fast motion in AE. But for some reason I can't see any change in my footage when I change the frame blend mode. The falling object will not blend in to other frames but rather stay still for several frames and then move and stay still again.
              • 4. Re: Slow motion question
                (Nic_Coe) Level 1
                Hi John,

                Are you doing a final render or a Ram preview, if you are doing a Ram Preview you have to turn on the Frame Blending Switch on the time line ... (the icon looks like film strips) ... otherwise you wont see the results.

                • 5. Re: Slow motion question
                  Level 1
                  If you're ever going to shoot footage that you want to slow down again make sure you shoot interlaced. This gives you 50 fields per second (or nearly 60 in NTSC land) so you'll get much better slow mo.

                  The technique goes like this.
                  1. Shoot Interlaced footage
                  2. Seperate fields in AE properly. 3rd party plug-ins can do a better job if you have the budget
                  3. Drag your footage into the new comp window to create the proper length comp
                  4. Open up the composition settings and double the frame rate. This is easy if you just highlight the field, move to the end of the numbers and type *2. AE will do the math for you.
                  5. Render this footage to a lossless codec. This will give you twice the number of frames to work with
                  6. Do your time stretching with the rendered footage. Here also, 3rd party plug-ins will do a better job

                  Even using only the tools that come with AE, you'll get much better slow mo using this technique than you can any other way.
                  • 6. Re: Slow motion question
                    Level 1
                    Thank you very much guys! I will try your suggestions. I really appreciate your help!
                    • 7. Re: Slow motion question
                      Jonas Hummelstrand Level 2
                      Here's how I did slowmotion with that camera a while back:
                      i http://www.vimeo.com/1870795

                      - Jonas Hummelstrand