Dell S199WFP review: input lag and deinterlacing using the piLagTesterPRO
This 19" 1440x900 PC monitor from 2009 uses a TN panel for fast response time/low lag, but has limited viewing angles. It has a glossy screen with vibrant colors, but plenty of reflections. It runs at up to 75z, and would be a fine (budget) gaming monitor.
Image quality
The set has no options to adjust cropping/scaling. There is mild aliasing outside the native resolution and no way to adjust the aspect ratio.
It has a glossy surface which gives very nice colors, but very visible reflections. Because it is a TN display the viewing angles are more limited than for most TVs or any IPS display
The display has VGA and DVI inputs. I tested DVI with a passive HDMI adapter.
Input Lag Results
I used a piLagTesterPRO to measure input lag. This device sends a frame of video over HDMI and measures how long it takes to display it. This display does not have a game mode.
I report two kinds of values. 1st response measures how long it takes for the monitor to start responding (I use a 5% change in display brightness). This overly optimistic value doesn't tell how long it takes to see anything useful, but matches what other reviewers call input lag. full response is a more realistic measure of lag, and requires the display to reach 80% of full brightness. This combines both input lag and response time, and is closer to what you would actually experience in a game.
| top | bottom | |||||
| Resolution | 1st (average) | full response | 1st response | full response | scan out | |
| 480i | 5.0 | 13.0 | 20.5 | 28.5 | 15.5 | |
| 480p | 4.5 | 12.5 | 19.8 | 27.8 | 15.3 | |
| 720p | 3.6 | 11.6 | 19.3 | 27.3 | 15.7 | |
| 1080p | 3.6 | 11.6 | 19.1 | 27.1 | 15.5 | |
| 1440x900x60 | 3.5 | 11.5 | 19.4 | 27.4 | 15.9 | |
| 1440x900x75 | 3.5 | 11.5 | 16.1 | 24.1 | 12.6 | |
The recommended resolution and refresh rate for this display is 1440x900x75hz, and it really draws at that refresh rate, but it also supports 60hz just as well, properly syncing with the vertical refresh to produce constant, steady input lag, which is about 4ms across all modes. Even interlaced is the same speed, because it uses the lag-free bob deinterlacing method. Note that the monitor does not advertise interlaced support, so you have to force this mode, but it works just fine.
We can go beyond the standard TV modes above and test each mode the monitor reports that it can support. Since the lag at the top of the screen doesn't change any, this data is recorded from the bottom of the screen:
| mode | res/refresh | bottom 1st response |
variability between frames |
| dmt#36 | 1024p75Hz | 16.2 | 0.07ms |
| dmt#48 | 900p75Hz | 16.1 | 0.03ms |
| dmt#21 | 864p75Hz | 16.3 | 0.15ms |
| dmt#11 | 600p75Hz | 16.4 | 0.12ms |
| dmt#18 | 768p75Hz | 16.4 | 0.17ms |
| dmt#6 | 480p75Hz | 16.5 | 0.06ms |
| dmt#10 | 600p72Hz | 16.9 | 0.21ms |
| dmt#5 | 480p72Hz | 17 | 0.05ms |
| dmt#17 | 768p70Hz | 17.3 | 0.16ms |
| dmt#35 | 1024p60Hz | 19.5 | 0.16ms |
| dmt#16 | 768p60Hz | 19.6 | 0.15ms |
| dmt#47 | 900p60Hz | 19.4 | 0.03ms |
| dmt#85 | 720p60Hz | 19.7 | 0.20ms |
| dmt#9 | 600p60Hz | 19.8 | 0.14ms |
| dmt#4 | 480p60Hz | 20 | 0.03ms |
| dmt#8 | 600p56Hz | 21 | 0.11ms |
As you can see faster refresh rates really do help overall lag. I also tried some unlisted 80hz modes but the monitor refused to sync to them.
Response time was about 8ms. It's fairly independent of the amount change between frames, but does have a overdrive artifact where it moves very quickly to about 80% of the final brightness, pauses a frame, and then jumps the rest of the way.
Results compared to other displays
To allow quick comparison between many displays I've summarized the results
across all the displays I've personally tested with the piLagTester Pro. Min
lag is the time to the first response, measured where the screen starts
drawing (typically, the top); real lag is the time to the full response,
measured where drawing finishes (usually the screen bottom), i.e. input lag +
scan out + response time. Numbers in red denote average values that can vary by
up to 8ms between power cycles.
This list is sorted by real lag for each display's native resolution and max
refresh rate, which gives this 75hz display a leg up over a 60hz monitor.
This display is quite near the top, helped out by the higher refresh rate. Though in fact all TN displays I have tested are quite competitive. Any TN computer monitor is going to have pretty good lag, even if it's from 2009. And any computer monitor is going to beat the pants of a TV.
Comments