ysenojftw wrote: ↑04 Dec 2021, 18:11
I’m also wondering if purexp adds input lag vs having it off completely. Can anyone chime in on this? I’m on 240hz, purexp normal, and capped fps at 500. If it doesn’t add input lag I think I’ll get used to the darker monitor.
The short answer is:
Yes and No. It depends.
It’s the same as DyAc/ELMB/VRB lag behavior.
Also, strobing reduces human reaction time for certain gaming tactics, so even if electronic lag is increased, human lag is decreased more — depending on gaming tactic you use.
The long answer is:
No added lag for some pixels, and some added lag for other pixels. Strobing modifies the latency gradient along the vertical axis of the screen. It’s a result of the asymmetry between global strobe flash, and LCD scanout in total darkness. So some pixels have no lag penalty and other pixels do.
A strobe backlight is a global flash, but a non-strobed LCD doesn’t refresh all pixels at the same time. See high speed videos of refresh cycles at
www.blurbusters.com/scanout …
Non-strobed modes = not all pixels become visible at the same time
Strobed modes = all pixels become visible at the same time.
So enabling/disabling a strobe backlight, affects the latency gradient along the vertical dimension on the screen for ALL strobe backlight technologies, including LightBoost, ULMB, VRB, ELMB, PureXP, DyAc, etc. If you average the latency difference for each pixel on the entire surface of the display, it is usually approximately half a refresh cycle, though longer pulse widths will affect this.
The human is considered part of the input lag chain in a way that is not easily measurable by electronic equipment. Most electronic equipment only measures via photons, not how fast the human reacts.
With less motion blur, it’s easier to identify targets faster, and react faster, and kill/kick/catch/etc items or targets faster. This can be very useful if you’re in perpetual motion such as Rocket League or RTS or MOBA games. For FPS games, whether you have reaction time improvements depends on whether you track eyes.
See
HOWTO: Using ULMB Beautifully or Competitively which explains this effect better.
Bottom line: For certain games, the improved human reaction time (reacting faster because of less motion blur) can sometimes outweigh the tiny lag increase from strobing. The average lag increase for a 240Hz strobe backlight is typically ~2ms, or 0.002s. A human reaction time is often closer to 200ms or 0.2s. However, if you even react 2-3% faster (e.g. 195ms), that already more outweighs the 2ms increase in strobe lag.
However, too-dim picture MAY make you react a bit slower, so adjust your brightness until a good sweet-spot compromise — bright enough that you have no problems playing, but strong enough motion blur reduction that the reduced blur makes you react faster.
Reviewers don’t measure human reaction time when measuring input lag. That’s the correct way to test monitors. However, it does not acknowledge how different modes of a monitor may influence (speed up) human reaction time to compensate for the electronic-timed lag increase of the monitor feature.
Does a millisecond matter? Yes, but it depends. See
The Amazing Human Visible Feats of the Millisecond, sometimes even 10 microseconds creates a human-visible effect. 1.0ms versus 1.01ms strobed MPRT is a 1% difference in photons, bigger than to RGB(253,253,253) versus RGB(255,255,255)
TL;DR; It is the same “quirk” behavior for all strobe backlights, including ULMB and DyAc, that is for sure. The same laws of physics applies to all of them. Some strobe backlights are laggier than others, but PureXP does the absolute minimum possible increase to lag, and you can adjust screen area for crosstalk, to decide where you want the lowest lag (The lowest lag is right above the crosstalk band).