Rolling shutter

The term rolling shutter refers to the manner in which certain video cameras present light to the in-camera sensors that receive the visual input from the environment.

As opposed to a global shutter, where the whole of the sensor is presented with light at once, resulting in the whole of the frame being captured simultaneously, with a rolling shutter, the image is captured sequentially in thin rows from top to bottom, one after the other, over the course of a single frame. [ [http://dvxuser.com/jason/CMOS-CCD/ "Barry Green: Sensor Artifacts and CMOS Rolling Shutter'] ]

This form of shutter is currently employed in certain video cameras that use a CMOS chip to capture light. Examples are the RED line of cameras, the Nikon D90 (in video mode), as well as Sony prosumer cameras like the PMW-EX1 [ [http://pro.sony.com/bbsc/ssr/cat-broadcastcameras/cat-xdcam/product-PMWEX1/ "Sony PMW-EX1 Product Details'] ] and PMW-EX3 [ [http://pro.sony.com/bbsc/ssr/cat-broadcastcameras/cat-xdcam/product-PMWEX3/ "Sony PMW-EX3 Product Details'] ] , among others.

Global shutters are primarily employed with the competing CCD chips, which utilize different technology in capturing light.

Rolling shutters have the potential to frustrate videographers by creating rolling shutter "artifacts" due to the possibility of the camera moving during the time when the top and bottom of a single frame are captured. This can result in issues such as "skew", "partial exposure" and what is colloquially known as the "Jellocam" phenomenon. [ [http://jackcabbage.blogspot.com/2008/06/sony-ex1-cmos-and-rolling-shutter.html "JackCabbage: CMOS and the Rolling Shutter'] ]

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