Vizio P65-F1 Pursuit Camera Tests and Review, 60hz Single-Strobing, 100hz, 120hz, TV BFI Discussion
Posted: 07 Aug 2020, 13:03
Very brightly backlit VA LCD TVs with local dimming could be an excellent and practical way to achieve very low persistence blur (MPRT) for gaming while further achieving a very high contrast ratio and great overall picture quality. Some high end LCD TV's have a peak brightness of nearly 3000 nits! The primary driving force for these uber-bright backlights is undoubtedly HDR. But as a side effect of all this extra brightness, some of these TVs can achieve impressively low persistence blur via BFI. This is wonderful considering these displays also prioritize great picture quality, wide color gamuts, and have much higher contrast ratios than most ULMB or related monitors with TN/IPS panels and without local dimming. They are perfect for gamers looking for great motion performance and great dark room performance out of the same display. 60hz single-strobing also makes these TVs far superior for console gaming, emulation, content consumption (e.g. YouTube, Twitch), and PC games that are limited to 60hz or otherwise have difficulty running at higher frame rates (such as many AAA games).
Last year I bought a 65" 2018 Vizio P Series TV (P65-F1) with motion performance that impressed me enough to give pursuit photography a shot and post about it here. Below are some (no rail, amateur) pursuit photos with my iPhone 7. Although the production value is lower than ideal, it should hopefully be good enough to gauge the motion performance of this TV along with similar models. This model is advertised as having ~1000 nit backlight. I am very curious if brighter models such as the ~3000 nit P Series Quantum X could perform much better.
If anyone is interested, I will mention the settings I have used on the TV when I took the videos. Even though this is a 4k TV, all videos were shot with a signal resolution of 1920x1080 with 100% windows scaling at 120hz, 100hz, and 60hz respectively. The backlight of the TV during testing was set to 0 with "clear action" (BFI) obviously enabled. This appears to be a very usable brightness unless you are in a brighter room. With BFI enabled, backlight is fully adjustable between 0-100 and is inversely proportional with motion clarity. This implies that the backlight setting is adjusting pulse width so the TV is always reducing the maximum amount of motion blur possible at any given brightness. At backlight 0, the brightness is ~100 nits. At backlight 100, the TV is over twice as bright but also with over twice as much persistence blur. I should note it is important that local dimming be set to "low" in order for BFI to be most effective on this TV. I am assuming this is because higher local dimming settings artificially over-brighten small window sizes. This could effectively increase the brightness of peak white in certain areas of the screen at certain times, which wastes backlight potential that could otherwise be used for lower persistence. The picture mode must also be set to Computer for full chroma to work and also to ensure BFI always flickers at the correct refresh rate, avoiding image duplications.
120hz pursuit camera screenshot [~1 ms of persistence blur (MPRT), ~100 nits]:
(960 Pixels Per Second) 120hz pursuit camera video: https://youtu.be/IlblA2qe-aw
100hz pursuit camera screenshot [~1.2 ms of persistence blur (MPRT), ~100 nits]:
(960 Pixels Per Second) 100hz pursuit camera video: https://youtu.be/A6Y_X5bBKgQ
IMPORTANT: For some reason, this TV cannot properly display a 100hz signal without chroma subsampling. I will post an update if I resolve the issue. You either need to set the picture mode to something other than "computer" or disable RGB/4:4:4 in your graphics driver settings. Attempting to send a full RGB 100hz signal will result in the bottom of the screen being cut off by a green bar.
60hz pursuit camera screenshot [~2 ms of persistence blur (MPRT), ~100 nits]:
(960 Pixels Per Second) 60hz pursuit camera video: https://youtu.be/FXTSvEsH3iw
NOTE: This TV is also capable of single-strobe 50hz BFI. It performs very similarly to 60hz but with slightly more blur and less strobe crosstalk. The flicker is extremely intense and I assume most people will never use it.
Any difference in color or brightness between the screenshots is due to the camera. Picture quality and brightness were identical for the three refresh rates tested. The moving aliens appear slightly less blurry in real life eye tracking then I was able to capture in these videos/screenshots. But I did my best. Likely limitations of an old camera and the hand-wave method. Also keep in mind the minor upscaling blur caused by displaying a 1920x1080 signal on a 4k panel (this was required for consistency at all refresh rates as the 2018 TV model tested lacks the HDMI 2.1 functionality required for 4k@120hz). I also tried to estimate the persistence/MPRT by comparing the clarity of the moving UFOs and pursuit photos to Blur Busters charts for visualizing persistence blur at 960 pixels per second. Please keep in mind that this is an amateur/end-user post and I lack any serious testing equipment.
I would also like to mention that it appears that this TV uses the local dimming zones to scan the backlight down the screen instead of strobing it all at once (somewhat like a CRT?). Anyone please correct me if I am misinterpreting this but I believe it to be a scanning backlight or rolling-strobe BFI. This could partially explain why I do not find the 60hz flicker of this TV to be particularly hard on the eyes, unless looking at an entirely white background. Rolling-strobe BFI should also in theory allow for maximally effective strobing on displays with local dimming as they can get brighter on smaller window sizes. The behavior at 50hz, 100hz, and 120hz is similar so I did not include slow motion videos for those refresh rates. I am curious if most TVs with local dimming do this? Do any monitors with local dimming do this?
Scanned 60hz BFI in iPhone 7 slow motion (play at 0.25 speed):
In terms of strobe crosstalk, it is basically perfectly uniform across the entire screen with 60hz BFI. At 100hz and 120hz BFI, strobe crosstalk varies across the screen. Strobe phase is unfortunately tied to the backlight setting at 100hz and 120hz (which also controls pulse width and perceived brightness). For example: I personally prefer ~100 nits of brightness while gaming. This corresponds to a backlight setting of ~0 on this TV during BFI. When the backlight is set to 0, 100hz BFI puts the least strobe crosstalk in the middle of the screen as most would prefer. At 120hz though, the backlight would need to be set brighter than 0, otherwise the sweet spot for strobe crosstalk is 80% up the screen and the bottom is less than ideal. 60hz strobe crosstalk works pretty much identically at all backlight settings.
My personal observations of this TV below:
Advantages:
- Scanned BFI could be slightly easier on the eyes and have lower input lag compared to other BFI methods
- Very low input lag on almost all modern 4k TVs
- Enabling BFI and/or game mode does not in any way change the overall picture quality, contrast, or local dimming performance (at least for Vizio TV's)
- Extremely deep blacks and contrast ratio with VA LCD and local dimming far exceed almost any ULMB/BFI monitor
- Native 60hz BFI works with any input including consoles and no need for a 60hz ULMB hack
- Pretty good pixel response times make strobe crosstalk not super noticeable, even at 120hz
- Industry leading HDR peak brightness and wide color gamut performance from TVs (especially ones with quantum-dot technology)
Disadvantages:
- 65" is far too large for typical desk usage
- Color washout and gamma shift with VA LCD at an angle (some expensive Samsung TVs have a "wide viewing angle layer" to compensate for this)
- VA black smearing often almost as bad as OLED
- Response time is not perfect and some strobe crosstalk is occasionally noticeable in games, strobe phase is not always where you want it to be at 100hz BFI and 120hz BFI depending on your preferred brightness
I can see TVs such as this one as being excellent for console gaming and emulation due to great picture quality and very effective 60hz BFI. The only thing stopping it from being excellent for PC gaming is its size. If you are able to use one for PC gaming though, there are some advantages. Many pretty AAA PC games cannot realistically be run at high frame rates so 60hz strobing is particularly helpful for improving the motion experience on those graphically and CPU-demanding titles. Content consumption is also especially improved, and I now find it difficult to enjoy YouTube or Twitch gaming videos without 60hz strobing. I am further tempted to say that one of these or a similar TV (especially a brighter one) would be an excellent low-persistence CRT-replacement for 60hz retro games without sacrificing much in terms of contrast ratio or picture quality (except for VA viewing angles). The native 60hz single-strobe BFI is just so immensely useful. It is such a shame that the vast majority of monitors will not even allow 60hz flicker by default. Furthermore, the difference in picture quality with local dimming enabled compared to a ULMB/BFI monitor is especially stark considering most monitors use TN or IPS technology with a poor contrast ratio (often made worse with ULMB/BFI enabled). The only major complaint I have of this TV overall is the viewing angles. I just hope "wide viewing angle layers" become more common among future VA LCDs. As a final note, I would be VERY INTERESTED to see pursuit camera tests done with Vizio's top-of-the-line Quantum X TV with a 3000 nit backlight. One could expect that display to perform three times as well as this one at motion blur reduction. At that point, it might be the best display available in terms of BFI capability. The Quantum X also appears to have the best BFI pursuit camera photos out of any TV reviewed on RTINGS.
Last year I bought a 65" 2018 Vizio P Series TV (P65-F1) with motion performance that impressed me enough to give pursuit photography a shot and post about it here. Below are some (no rail, amateur) pursuit photos with my iPhone 7. Although the production value is lower than ideal, it should hopefully be good enough to gauge the motion performance of this TV along with similar models. This model is advertised as having ~1000 nit backlight. I am very curious if brighter models such as the ~3000 nit P Series Quantum X could perform much better.
If anyone is interested, I will mention the settings I have used on the TV when I took the videos. Even though this is a 4k TV, all videos were shot with a signal resolution of 1920x1080 with 100% windows scaling at 120hz, 100hz, and 60hz respectively. The backlight of the TV during testing was set to 0 with "clear action" (BFI) obviously enabled. This appears to be a very usable brightness unless you are in a brighter room. With BFI enabled, backlight is fully adjustable between 0-100 and is inversely proportional with motion clarity. This implies that the backlight setting is adjusting pulse width so the TV is always reducing the maximum amount of motion blur possible at any given brightness. At backlight 0, the brightness is ~100 nits. At backlight 100, the TV is over twice as bright but also with over twice as much persistence blur. I should note it is important that local dimming be set to "low" in order for BFI to be most effective on this TV. I am assuming this is because higher local dimming settings artificially over-brighten small window sizes. This could effectively increase the brightness of peak white in certain areas of the screen at certain times, which wastes backlight potential that could otherwise be used for lower persistence. The picture mode must also be set to Computer for full chroma to work and also to ensure BFI always flickers at the correct refresh rate, avoiding image duplications.
120hz pursuit camera screenshot [~1 ms of persistence blur (MPRT), ~100 nits]:
(960 Pixels Per Second) 120hz pursuit camera video: https://youtu.be/IlblA2qe-aw
100hz pursuit camera screenshot [~1.2 ms of persistence blur (MPRT), ~100 nits]:
(960 Pixels Per Second) 100hz pursuit camera video: https://youtu.be/A6Y_X5bBKgQ
IMPORTANT: For some reason, this TV cannot properly display a 100hz signal without chroma subsampling. I will post an update if I resolve the issue. You either need to set the picture mode to something other than "computer" or disable RGB/4:4:4 in your graphics driver settings. Attempting to send a full RGB 100hz signal will result in the bottom of the screen being cut off by a green bar.
60hz pursuit camera screenshot [~2 ms of persistence blur (MPRT), ~100 nits]:
(960 Pixels Per Second) 60hz pursuit camera video: https://youtu.be/FXTSvEsH3iw
NOTE: This TV is also capable of single-strobe 50hz BFI. It performs very similarly to 60hz but with slightly more blur and less strobe crosstalk. The flicker is extremely intense and I assume most people will never use it.
Any difference in color or brightness between the screenshots is due to the camera. Picture quality and brightness were identical for the three refresh rates tested. The moving aliens appear slightly less blurry in real life eye tracking then I was able to capture in these videos/screenshots. But I did my best. Likely limitations of an old camera and the hand-wave method. Also keep in mind the minor upscaling blur caused by displaying a 1920x1080 signal on a 4k panel (this was required for consistency at all refresh rates as the 2018 TV model tested lacks the HDMI 2.1 functionality required for 4k@120hz). I also tried to estimate the persistence/MPRT by comparing the clarity of the moving UFOs and pursuit photos to Blur Busters charts for visualizing persistence blur at 960 pixels per second. Please keep in mind that this is an amateur/end-user post and I lack any serious testing equipment.
I would also like to mention that it appears that this TV uses the local dimming zones to scan the backlight down the screen instead of strobing it all at once (somewhat like a CRT?). Anyone please correct me if I am misinterpreting this but I believe it to be a scanning backlight or rolling-strobe BFI. This could partially explain why I do not find the 60hz flicker of this TV to be particularly hard on the eyes, unless looking at an entirely white background. Rolling-strobe BFI should also in theory allow for maximally effective strobing on displays with local dimming as they can get brighter on smaller window sizes. The behavior at 50hz, 100hz, and 120hz is similar so I did not include slow motion videos for those refresh rates. I am curious if most TVs with local dimming do this? Do any monitors with local dimming do this?
Scanned 60hz BFI in iPhone 7 slow motion (play at 0.25 speed):
In terms of strobe crosstalk, it is basically perfectly uniform across the entire screen with 60hz BFI. At 100hz and 120hz BFI, strobe crosstalk varies across the screen. Strobe phase is unfortunately tied to the backlight setting at 100hz and 120hz (which also controls pulse width and perceived brightness). For example: I personally prefer ~100 nits of brightness while gaming. This corresponds to a backlight setting of ~0 on this TV during BFI. When the backlight is set to 0, 100hz BFI puts the least strobe crosstalk in the middle of the screen as most would prefer. At 120hz though, the backlight would need to be set brighter than 0, otherwise the sweet spot for strobe crosstalk is 80% up the screen and the bottom is less than ideal. 60hz strobe crosstalk works pretty much identically at all backlight settings.
My personal observations of this TV below:
Advantages:
- Scanned BFI could be slightly easier on the eyes and have lower input lag compared to other BFI methods
- Very low input lag on almost all modern 4k TVs
- Enabling BFI and/or game mode does not in any way change the overall picture quality, contrast, or local dimming performance (at least for Vizio TV's)
- Extremely deep blacks and contrast ratio with VA LCD and local dimming far exceed almost any ULMB/BFI monitor
- Native 60hz BFI works with any input including consoles and no need for a 60hz ULMB hack
- Pretty good pixel response times make strobe crosstalk not super noticeable, even at 120hz
- Industry leading HDR peak brightness and wide color gamut performance from TVs (especially ones with quantum-dot technology)
Disadvantages:
- 65" is far too large for typical desk usage
- Color washout and gamma shift with VA LCD at an angle (some expensive Samsung TVs have a "wide viewing angle layer" to compensate for this)
- VA black smearing often almost as bad as OLED
- Response time is not perfect and some strobe crosstalk is occasionally noticeable in games, strobe phase is not always where you want it to be at 100hz BFI and 120hz BFI depending on your preferred brightness
I can see TVs such as this one as being excellent for console gaming and emulation due to great picture quality and very effective 60hz BFI. The only thing stopping it from being excellent for PC gaming is its size. If you are able to use one for PC gaming though, there are some advantages. Many pretty AAA PC games cannot realistically be run at high frame rates so 60hz strobing is particularly helpful for improving the motion experience on those graphically and CPU-demanding titles. Content consumption is also especially improved, and I now find it difficult to enjoy YouTube or Twitch gaming videos without 60hz strobing. I am further tempted to say that one of these or a similar TV (especially a brighter one) would be an excellent low-persistence CRT-replacement for 60hz retro games without sacrificing much in terms of contrast ratio or picture quality (except for VA viewing angles). The native 60hz single-strobe BFI is just so immensely useful. It is such a shame that the vast majority of monitors will not even allow 60hz flicker by default. Furthermore, the difference in picture quality with local dimming enabled compared to a ULMB/BFI monitor is especially stark considering most monitors use TN or IPS technology with a poor contrast ratio (often made worse with ULMB/BFI enabled). The only major complaint I have of this TV overall is the viewing angles. I just hope "wide viewing angle layers" become more common among future VA LCDs. As a final note, I would be VERY INTERESTED to see pursuit camera tests done with Vizio's top-of-the-line Quantum X TV with a 3000 nit backlight. One could expect that display to perform three times as well as this one at motion blur reduction. At that point, it might be the best display available in terms of BFI capability. The Quantum X also appears to have the best BFI pursuit camera photos out of any TV reviewed on RTINGS.