How do I measure my monitor's response time?

[Freezanator]

Title says it all. I used Blur Busters UFO Motion Test and got 15.3ms for "Persistence". Is persistence the same as response time? Thanks!  

[xAcid9]

Got money? Buy this Leo Bodnar input lag tester.

http://www.leobodnar.com/shop/?main_page=product_info&products_id=212

 

 

[Freezanator]

Just now, xAcid9 said:

Got money? Buy this Leo Bodnar input lag tester.

http://www.leobodnar.com/shop/?main_page=product_info&products_id=212

 

 

Nope, no money.

[Naeaes]

13 minutes ago, Freezanator said:

Nope, no money.

No soup for you then!

 

It's possible to jerryrig a makeymakey to function as a kind of inputlag testing device. You'd set it to light up an on-board LED and send a signal like a keypress to the computer. Then film the process on a highspeed camera and count frames between the LED lighting up and a change on the screen to calculate the delay. The problem is that a current gen phone would have like a 120FPS camera which is more than 8ms resolution. That's way too coarse for measuring any kind of decent input lag It's in the milliseconds, not in tens of milliseconds. A better camera can have a higher framerate and better resolution but again, money. Also, this method includes all the internal delay of the makeymakey, delay from USB, the processing time of your CPU, the processing time of your GPU and the delay from the cables, none of which is your monitor's fault.

 

Now that I think of it, you might be able to simply use a camera and a keyboard with a visible num/caps/scroll lock LEDs if you set up a software/script to pop something up on the screen. So if you have access to a camera with like 1000FPS recording, you could get some figures for free. 

[Freezanator]

2 minutes ago, Naeaes said:

No soup for you then!

 

It's possible to jerryrig a makeymakey to function as a kind of inputlag testing device. You'd set it to light up an on-board LED and send a signal like a keypress to the computer. Then film the process on a highspeed camera and count frames between the LED lighting up and a change on the screen to calculate the delay. The problem is that a current gen phone would have like a 120FPS camera which is more than 8ms resolution. That's way too coarse for measuring any kind of decent input lag It's in the milliseconds, not in tens of milliseconds. A better camera can have a higher framerate and better resolution but again, money. Also, this method includes all the internal delay of the makeymakey, delay from USB, the processing time of your CPU, the processing time of your GPU and the delay from the cables, none of which is your monitor's fault.

 

Now that I think of it, you might be able to simply use a camera and a keyboard with a visible num/caps/scroll lock LEDs if you set up a software/script to pop something up on the screen. So if you have access to a camera with like 1000FPS recording, you could get some figures for free. 

Sorry, I meant "Informative". 

[Glenwing]

6 hours ago, xAcid9 said:

Got money? Buy this Leo Bodnar input lag tester.

http://www.leobodnar.com/shop/?main_page=product_info&products_id=212

 

 

This measures latency, not response time. Response time is the time it takes the pixels to physically change colors once they have started changing, not the delay before they start changing.

5 hours ago, Naeaes said:

No soup for you then!

 

It's possible to jerryrig a makeymakey to function as a kind of inputlag testing device. You'd set it to light up an on-board LED and send a signal like a keypress to the computer. Then film the process on a highspeed camera and count frames between the LED lighting up and a change on the screen to calculate the delay. The problem is that a current gen phone would have like a 120FPS camera which is more than 8ms resolution. That's way too coarse for measuring any kind of decent input lag It's in the milliseconds, not in tens of milliseconds. A better camera can have a higher framerate and better resolution but again, money. Also, this method includes all the internal delay of the makeymakey, delay from USB, the processing time of your CPU, the processing time of your GPU and the delay from the cables, none of which is your monitor's fault.

 

Now that I think of it, you might be able to simply use a camera and a keyboard with a visible num/caps/scroll lock LEDs if you set up a software/script to pop something up on the screen. So if you have access to a camera with like 1000FPS recording, you could get some figures for free. 

This measures the entire latency chain from a mouse input to the display, not just the delay of the display itself. It can be useful if you have access to a display with known latency though, since you can use that as a reference point to subtract off the "system" latency.

 

As for a camera, the Casio ZR100 is probably the best "cheap" option for this, it's about $150 and can shoot at 1,000 fps, so every frame is 1 ms. You can also get a "visual" estimate of response time with this camera by watching the pixels change on the screen. You can see it at 1,000 fps, so you can just count the number of frames it takes to change.

 

But if you want to really "measure" the response time for real, you need a light-to-voltage converter and an oscilloscope.

 

Interestingly, I have done all of these things

 

Bearing in mind response time is not a single number, it changes depending on the starting and ending color, here are some sample figures for my Dell U2414H ("8 ms" 60 Hz IPS monitor), using a Tektronix TBS-1152 scope and a TLS253 sensor as a light to voltage converter.

 

(note that the frequency displayed on the scope is half the framerate, so "30 Hz" = 60 fps or 60 Hz on the monitor)

 

#000000 to #FFFFFF: 5.96 ms
#FFFFFF to #000000: 7.54 ms


#969696 to #FFFFFF: 5.33 ms

#FFFFFF to #969696: 9.26 ms

 As always, Dell is somewhat conservative with their response time measurements, I'd say "8 ms" is a good estimate if you really wanted to represent it by a single number for some reason. Response time for rising transitions is usually around 5-7 ms and falling transitions are a bit longer, maybe 7-9 ms.

 

 

and for my ViewSonic XG2401 ("1 ms" 144 Hz TN monitor)

 

 

#000000 to #FFFFFF: 4.46 ms
#FFFFFF to #000000: 680 µs (0.68 ms!)


#969696 to #FFFFFF: 4.39 ms
#FFFFFF to #969696: 3.84 ms

This monitor has sub-1 ms response times for a few falling transitions (faster the lower the ending color), but rising transitions are pretty much always around 4 ms. At falling transitions to higher colors (like FF to 96 shown here) it's nowhere near a 1 ms response time. Personally I would have labeled this as a 4 ms monitor.