Now there are many consumer level camera can shoot high-frame rate video. However, there is sacrificing of effective pixels as the frame rate increase. Here I'm going to take SONY RX10M3 as example. Below show the relationship: enter image description here

In the manual, the effective pixel is 1136×384 for 1000FPS. My question is, let's say the sensor is a square, does the effective pixel is at the center of the actual sensor? Or is it scattered all around the sensor? I'm curious about this. Depiction:


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    You wouldn't want your field of view to change drastically as you go from photo to video mode, so I believe it spreads the pixels across the image (minus any adjustment due to aspect ratio difference). But another related question is, does it simply take one physical pixel out of the effective pixel or does it try to average over the entire block? – Mark Ransom Apr 6 '17 at 22:17
  • Nice speculation! I have a chance to experience with the Sony RX10M3, so I tried out your idea. It seems that when the mode was changed from 'normal'(full frame) video shooting mode to HFR shooting mode, the FOV did actually changed. The FOV in HFR mode is smaller(cropped). – Gregor Isack Apr 7 '17 at 1:49

The various digital cameras I've owned all read out the central block of pixels. This is not particularly surprising if you consider the what actually happens if you try to read out scattered pixels. If you collect pixels 1:N or 10:(N-10), you've collected a section of the image. If instead you collect pixels 1:5:N , you're subsampling the entire image and losing signal from portions of the image (not just resolution). This would lead to a choppy image rather than a slightly blurred image; the latter being what you get with a N/10 X N/10 vs N X N pixel array.


A good explanation is provided in the article Sensors 2009, 9, 430-444; doi:10.3390/s90100430. Basically it talks about how much time is required for chip I/O to send a converted digital result from a sensor pixel (or a group of pixels). So all the sensor pixels cannot be used at a time and the effective pixels is reduced.

  • PLease edit to turn your reference into a URL. But in any case, you're not addressing the question. – Carl Witthoft Apr 7 '17 at 11:23

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