Circle of Confusion and Depth of Field in Stereoscopic 3D (image copyright burned in image)

Circle of Confusion and Depth of Field in Stereoscopic 3D (image copyright burned in image)

Depth of Field and Stereoscopic 3D:

Understanding the effects of Depth of Field and it’s effect on stereoscopic 3d imagery and more importantly the effect it has on audiences minds is something that has not been researched or studied well. DoF is an important tool in 2D Cinematography and in-fact is much coveted as it’s one of the big things that gives a feature Film…it’s “film look”. To explain it briefly, in the picture above the Cat or object B is what is in sharp focus on the camera sensor, or as an analogy, the retina of the eye. The images of the rabbit and the dog do not come into sharp focus and only parts of it are in focus, and rapidly become un-sharp. The “circle of confusion” is thus illustrated in the image above.

When watching such an image in 2D, it helps the Cinematographer or director to direct the attention of the viewer to the area that is in sharpest focus. Try this in a stereoscopic 3D image, and you will create eye-strain in viewers eyes, as the powerful optical illusion that is “3D” forces the brain to send commands to the eyes to try and “fuse” the un-sharp areas. To the brain, a stereoscopic 3D image is after all… similar to the real world.

Trying another 2D Cinematic technique, …

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  • clydeD

    Notice in “point 1” how it says that the stereographer could choose to isolate a player…etc… This brings up an interesting question in Live 3D Coverage of Sports, namely, with regards to a live production enviroment the main variables I see that cause a bottle neck to a smooth live experience both for the production crew and as a result to the end viewers (and again strictly in a live enviroment) is:

    1) The need for a stereographer to communicate with the online-editor / Director. I think either the Stereographer him(her)self needs to be triggering the live mix or the online-editor should go through intensive stereoscopy training.
    More often it will be the stereographer that can adapt more easily.

    2) Of course thorough training has to go into “learning” the sport and “what comes next” scenarios. For example in Soccer..what move is likely to follow a corner kick, in Golf what to focus on (figuratively speaking) after the swing…

    By knowing what-comes-next, the appropriate camera can be primed and be ready to cut to..at the proper Depth setting and framing. I know at this point it's usually the online-editor (director) who calls out the shots to the cameraman in the field, telling him to be ready to go live… but if the stereographer makes this “call” he can shave off a few precious seconds and anticipate correct depth and set i/a as he knows ahead of time, by looking at the preview monitors, what the next likely cam to be cut to would be, rather than having to nudge the On-line editor to call out the choice. Of course this also means the stereographer would have to do double duty and be DoP as well, to set appropriate f-stop, unless this is assisted by the semi-automation of the rig.

    This makes all the difference in the world for a seamless 3D experience to end viewers.
    Recent events had stereographers adjusting and “ramping” convergence While the signal was live!.. not in an experienced way, but in a manner suggesting trying to get the optimal depth.

  • Anonymous

    Notice in “point 1” how it says that the stereographer could choose to isolate a player…etc… This brings up an interesting question in Live 3D Coverage of Sports, namely, with regards to a live production enviroment the main variables I see that cause a bottle neck to a smooth live experience both for the production crew and as a result to the end viewers (and again strictly in a live enviroment) is:

    1) The need for a stereographer to communicate with the online-editor / Director. I think either the Stereographer him(her)self needs to be triggering the live mix or the online-editor should go through intensive stereoscopy training.
    More often it will be the stereographer that can adapt more easily.

    2) Of course thorough training has to go into “learning” the sport and “what comes next” scenarios. For example in Soccer..what move is likely to follow a corner kick, in Golf what to focus on (figuratively speaking) after the swing…

    By knowing what-comes-next, the appropriate camera can be primed and be ready to cut to..at the proper Depth setting and framing. I know at this point it’s usually the online-editor (director) who calls out the shots to the cameraman in the field, telling him to be ready to go live… but if the stereographer makes this “call” he can shave off a few precious seconds and anticipate correct depth and set i/a as he knows ahead of time, by looking at the preview monitors, what the next likely cam to be cut to would be, rather than having to nudge the On-line editor to call out the choice. Of course this also means the stereographer would have to do double duty and be DoP as well, to set appropriate f-stop, unless this is assisted by the semi-automation of the rig.

    This makes all the difference in the world for a seamless 3D experience to end viewers.
    Recent events had stereographers adjusting and “ramping” convergence While the signal was live!.. not in an experienced way, but in a manner suggesting trying to get the optimal depth.