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View Full Version : Motion Blur (on different media)


Krix
03-15-2003, 02:23 PM
Hi All,


We all know the importance of motion blur and the right settings to match with live action, or just to be realistic in computer animation. The shutter angle of the camera defines the length of the motionblur value on the recorded film. Probably everybody (watching films) notices the differences between film, DV, Betacam,...or any kind of video camera. Film can produce deeper colors, than video, also smoother outlines, higher details...etc compared to video's harsh, "colorless", high contrasted output.
My question is to all experienced special FX guys:

What about motion blur? In what ways do these recording methods react to motion? Are they producing different motionblur? Or do different shutter angles produce different lenght of motion blur on different media?

Thank you!

Krix

Cogliostros
03-15-2003, 04:08 PM
Video is usually typically more sharp and lacks motion blur, due to interlacing... video runs at 30fps and you have 2 fields for every frame of video, so thats 60 images per second resulting in a sharp image with little motion blur... where as in film you have 24fps and its full frame so you don't lose information or have artifacts between 2 fields... if your camera can shoot in progressive mode you can better match motion blur scanning the frame once.

You can test it out for yourself... set up a practical shoot with an object that you can manipulate to move at the same speed consistantly and moving fast enough to give you some noticeable motion blur... Shoot this with any and all of the types of media you can, DV Cam, Digital Camera, Practical Camera, other camcorders, and film if you could... in film cameras there is a chemical reaction occuring when the light hits the film resulting in the exposure so this will differ from digital video, and digital cameras, etc... in how the image is captured to tape or stored in memory, but will our eye really notice the difference?

You could build a library of motion blurs using different media at different shutter speeds and aperatures, with objects that move at different speeds and use that to reference for going into cg and trying to achieve the right blur.

Just realize typically it works like this, longer shutter speeds let more light in exposing the film longer resulting in longer motion blurs... but this is also relative to the speed of the object in camera... Faster shutter speeds will have shorter motion blurs. The size of the aperature also comes into play, letting more or less light in.

Depending on the camera, with DV Cameras you can set it up to match the motion blur of film... The shutter speed should be set as slow as possible in order to get a degree of motion blur that resembles the look of film shot with a normal 180 degree shutter.

Hope this helps...

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