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Bizkitcan Posted at 2017-2-4 21:32
DJI OSMO Mobile has significant issues with the iPhone 7+.... All of the above, here is some juddering while tracking. https://www.youtube.com/watch?v=Tko9oVS4chQ
To me the judder is more due to frame rate mismatch somewhere. It is sometimes caused by the "TV" rates vs "computer" rates (23.976 FPS vs 24 FPS) played back on 60 Hz monitor, sometimes there is a frame skipped or added, causing little periodic judder easily seen in motion footage.
Some editors make this worse as well. That is not caused by the gimbal. It also looks little different, like a little studder.
The problem with the gimbal is rather slow bobbing, caused by the fact that the whole rig moves up and down a little as you walk. That is much smoother and slower oscillation of the whole image, looks like it were filmed on a boat in smooth waves, corresponding to the steps. That one is really not caused by the stabilizer, but by the fact that these are only 3 axes stabilizers, that don't stabilize vertical motion at all. That's why you are asked to do the "Ninja walk". Big Steadicams do the same thing, until the operator straps on a vest with a spring balancing scheme, that stabilizes the cameras from bouncing up and down (4th axis stabilization). The heavier the camera the better, that system is basically a mechanical low pass filter. Often the Steadicam operator walks in fast cadence, sort of tiptoe, because the faster frequencies with lower amplitudes don't transfer to the camera as much. Sort of like car suspension system (old heavy Cadillacs - they don't vibrate with the road surface, but follow the hills).
The electronic camera stabilizer acts like the car suspension, it "zooms" electronically into the frame a little and "moves" around as it picks smaller part the sensor. The "zoomed" output appears to be following the operator's aim slowly, and ignores quick moves along any axis. If you deploy it, and use the proper gimbal mode so that the camera doesn't change pitch or pan as you walk, it will help with the 4th axis stabilization (bobbing). Best thing is to keep the gimbal in a mode where it points exactly the same direction during given clip capture, and try to keep the individual takes not too long.
The same techniques (zoom into the frame and move around it) is used when stabilizing in Post with editors that offer stabilization. Those have the advantage that you can "dial" up or down how aggressive you want the stabilization (zoom) for given part of the clip, so you don't lose too much of the frame.
They also have ability to minimize the "jello effect" caused by the "rolling shutter" of the CMOS sensors that just about all the cameras use these days.
So there are several stabilizers involved - a mechanical one (steadicam, gimbal), outside the camera, inside the camera can be OIS and/or EIS - none of these effect output resolution or detail. There maybe additional EIS in the software, such as Camera or Filmic Pro - these do effect the frame detail and can be generally turned off. Finally there can be stabilization in the editor (Post) that, if there, is also selectable and does effect the frame detail. (I purposely say detail instead of resolution, because that is another subject of discussion that is generally not understood).
Finally, if you do this, it is better to take the video in higher resolution than the one you wish to publish, so you don't lose details as you "zoom in" as long as your final output resolution is lower than the capture one. The camera electronic stabilizer and the Post stabilizer in the editor, work on the same principle, but have different impact and advantages both.
Too me too much is expected from the gimbal, and therefore too much is blamed on it. |
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