This, and the linked article, show the photo sensor halfway the monitor. Nothing wrong with that for comparing measurements, but for quite a lot (possibly the m

This, and the linked article, show the photo sensor halfway the monitor. Nothing wrong with that for comparing measurements, but for quite a lot (possibly the majority) of typical monitors out there that actually means for a refresh of 60Hz putting the sensor at the top of the screen will give you about 8mSec faster and at the bottom 8mSec slower measurements because pixels / lines thereof are driven top to bottom. Like a CRT basically. So if you're getting into the details (just like where to put the threshold on the photo sensor signal to decide when the pixel is on) that should probably be mentioned. Also because 8mSec is quite the deal when looking at the numbers in tha article :) Likewise just saying 'monitor x' is 30mSec slower than 'monitor y' can be a bit of a stretch; it's more like 'I measured this to be xxmSec slower on my setup with settings X and Y and Z'. I.e. should also check if the monitor isn't applying some funny 'enhancement' adding latency with no perceivable effect but which can be turned off, whether when switching monitors your graphics card and/or its driver didn't try to be helpful and magically switched to some profile where it tries to apply enhancements, corrections, scaling and whatnot which add latency. All without a word of warning from said devices usually, but these are just a couple of the things I've seen.