They're definitely not measuring screen centre. They say the signal processing at 144 Hz is 10.2 ms and at 60 Hz it's 7.4 ms and they have monitors reviewed with times as low as 2ms which would be impossible at the centre of the screen with VSYNC ON. Funnily enough they say how they obtained their data for everything in their test except the signal processing. I might write a mail and ask them.Chief Blur Buster wrote:They're probably measuring screen centre, VSYNC ON.
As for my other problems:
I switched to a green LED which is way brighter with the same resistor even though it's supposed to require almost twice the voltage of the red one. Yes, I know the eyes are more sensitive to green light but so are camera sensors with a bayer filter. I also moved it right in front of the lens so it's very obvious now when it's on and when not. It's also easy to see the rolling shutter this way since the LED is sometimes turning on halfway into the frame. In fact it works so well it should be possible to get sub millisecond accuracy of the LED turn on time just by looking at where the first bit of green shows but it obviously doesn't work the same way for the screen. And I should be able to figure out how long it takes for the LED to turn on.
Smashing my mouse button hard didn't seem to make any difference for how fast the LED turned on. But I had a different idea. I can just use the button on the breadboard which works fine. Essentially doing the opposite of the setup you proposed. Not pressing the mouse button to also light up the LED but click the other button to also trigger a mouse click. Do you guys think there is any reason I shouldn't do this? I know that it is not a perfect representation of how the mouse will perform but I can't see a brand new gaming mouse button being any worse than one of those cheap buttons that seem to work fine.
Anyway, I repeated my test with the new setup (50 trials again). Same min/max. Median dropped to 14 ms and mean dropped by 0.66 ms. Considering that the LED now covers the entire side of the camera which means that I can see it even if turns on at the latest possible moment during the rolling shutter scanout, you'd expect the times to go up. So I think it's pretty safe to say that the actual mouse button was causing extra delay.