What is acceptable latency between reality and viewfinder?

There was an interesting discussion on irc : https://www.apertus.org/irc/index.php?day=19&month=11&year=2013

My take on that (Philippe) : There *is* some delay between reality and what is shown on the display, in any camera. Altough this delay is as minimal as possible. It is hard to say how much is too much, less than a frame means less than 41 milliseconds. I guess we can achieve much better, like 10 msec delay. Which I'd translate as humanly not perceivable. not counting exposure time btw)

Interesting summary : http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5540888&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D5540888 Another one, focused on video games, an area where latency is studied quite well : http://enterthesingularity.blogspot.be/2010/04/latency-human-response-time-in-current.html

From their experimental results :

  • 300ms> games become unpleasant, even unplayable
  • 200ms> delay becomes palpable
  • 100-150ms - limit of delay detection for full scene actions - camera panning and so on
  • 50-60ms - absolute limit of delay detection - small object tracking - mouse cursors50-60ms - absolute limit of delay detection - small object tracking - mouse cursors

Assuming 41 ms exposure (at 24fps) + 10 ms processing, we are in the 50 ms ballpark of unnoticeable latency.