4 ms·

It’s not that the frames blend in the screen. Screens are perfectly capable of switching the pixels fast enough. It’s rather that each frame is displayed for to

It’s not that the frames blend in the screen. Screens are perfectly capable of switching the pixels fast enough. It’s rather that each frame is displayed for to long. In a CRT the “pixels” start to fade immediately leaving the full screen mostly dark as the beam sweeps over the screen. It never shows a full frame. One could say that modern screens are more like slide shows, while BFI tries to make them more like stroboscopes. The blurring effect is more pronounced ate low refresh rates, its just that BFI requires at least 120hz to male sense at all.

fulafel 2y ago
CRTs don't darken that fast, one way to observe this is that CRTs don't appear black in photos/video with shutter times << 1/60
- yuriks 2y ago
  They do darken that fast (not fast enough you can't catch it in a high speed camera, but much faster than a frame). Most of the apparent persistence in the CRT comes from the retina/camera exposure, not the phosphor. A CRT has a sharp peak of light that quickly falls off, but the peak is bright enough that even though it is brief, when averaged out in an exposure in the camera it still appears bright enough to form an image.
- chowells 2y ago
  You've never taken photos of a CRT, have you? Even at like 400 ISO equivalent, only about a third of the screen is illuminated.
- rcxdude 2y ago
  They frequently flicker or are only showing part of an image in video footage or photos, for exactly this reason. They're a right headache to film clearly. (see this youtube video showing one in slow-motion to get an idea: https://www.youtube.com/watch?v=3BJU2drrtCM https://www.youtube.com/watch?v=3BJU2drrtCM)
  - fulafel 2y ago
    Thanks for the link. It seems i'd concluded this a bit wrong from seeing those half lit frames (like at 1:35 of this YT video).
tigen 2y ago
Yes, the relevant blur here is in your retina, as it tracks a moving screen object, called "sample and hold" blur. 60 fps is not enough when the pixel persists for the full frame duration -- the pixels smear across your retina.

fulafel 2y ago

CRTs don't darken that fast, one way to observe this is that CRTs don't appear black in photos/video with shutter times << 1/60

yuriks 2y ago
They do darken that fast (not fast enough you can't catch it in a high speed camera, but much faster than a frame). Most of the apparent persistence in the CRT comes from the retina/camera exposure, not the phosphor. A CRT has a sharp peak of light that quickly falls off, but the peak is bright enough that even though it is brief, when averaged out in an exposure in the camera it still appears bright enough to form an image.
chowells 2y ago
You've never taken photos of a CRT, have you? Even at like 400 ISO equivalent, only about a third of the screen is illuminated.
rcxdude 2y ago
They frequently flicker or are only showing part of an image in video footage or photos, for exactly this reason. They're a right headache to film clearly. (see this youtube video showing one in slow-motion to get an idea: https://www.youtube.com/watch?v=3BJU2drrtCM https://www.youtube.com/watch?v=3BJU2drrtCM)
- fulafel 2y ago
  Thanks for the link. It seems i'd concluded this a bit wrong from seeing those half lit frames (like at 1:35 of this YT video).

tigen 2y ago

Yes, the relevant blur here is in your retina, as it tracks a moving screen object, called "sample and hold" blur. 60 fps is not enough when the pixel persists for the full frame duration -- the pixels smear across your retina.