Giant 120Hz + “LightBoost” on Optoma GT720 DLP Projector


Several readers have written in to confirm that the Optoma GT720 successfully runs a true 120Hz refresh rate for 2D gameplay.

This DLP has black frame insertion (BFI) in 3D mode that also improves motion clarity during 120Hz 2D operation, like LightBoost.

This projector is 1280×720 DLP, 2500 ANSI lumens, and image sizes up to 150 inch! Giant 120Hz gaming for under $1K.
Edit: GT750 now confirmed to do 120Hz. The GT760 likely does as well.

Link: Manufacturer Page and Amazon.com

About Chief Blur Buster

Chief Blur Buster

12 comments on “Giant 120Hz + “LightBoost” on Optoma GT720 DLP Projector

  1. Chief Blur Buster says:

    If 120Hz is missing from EDID, there’s an easy solution:

    To get 120Hz during 1280x720p, download ToastyX Custom Resolution Utility (or use nVidia Custom Resolution Utility) and add the 120Hz refresh rate, and it will work. For more technical information, see HOWTO: True 120Hz From PC to TV.

    No overclocking is involved. The projector natively supports 120Hz according to the manufacturer specs page. (Frame-sequential 3D at 60Hz+60Hz = 120Hz). The 120Hz is originally for 3D, but works perfectly with computers for 2D gameplay.

  2. Chief Blur Buster says:

    A user has reported that this DLP enables black frame insertion when the 3D mode is enabled. This increases motion resolution of this DLP even further (like having LightBoost, but at big screen sizes).

    This DLP has CRT-like motion resolution; it is able to pass the TestUFO: Moving Map Test — something very few displays can do (CRT displays, LightBoost displays, and certain better plasma models.

  3. rdqlus says:

    I’m the user that reported this on [H]ardForum. I’ve been using 3 Optoma GT720 projectors in Eyefinity/Surround for over a year now and it’s pretty much a perfect FPS setup. The only downfall is that the competitive shooters (Quake Live, CS:GO, etc.) have limited support for Eyefinity/Surround. So I’m limited to (arguably more popular) games like BF:BC2 or BF3.

    I only found the video tests on TestUFO a couple days ago and tried them out. The projectors do a pretty damn good job.

    Note:
    720p@120Hz is supported by the projector out-of-the-box. I enabled support for 800p@120Hz by creating a custom EDID using an editor. The EDID is available on the WSGF forum for anyone that wants it.

  4. Chief Blur Buster says:

    Confirmed. According to high speed camera tests — yes — the GT720 is doing black frame insertion when “3D Mode” is enabled.

    I’m surprised BENQ never advertised this as a blur reduction mode, but it appears to roughly double motion resolution above-and-beyond just going to 120Hz. This means this DLP projector has about 4x the motion resolution of the typical computer DLP projector. This is quite a dramatic improvement.

    I wonder how many other DLP projectors are doing undocumented black frame insertion, whenever you enable 3D mode. (A black period is useful between frames for reducing 3D crosstalk, since time is needed for shutter glasses to switch eyes). This also directly benefits motion clarity during 2D mode.

    • Chief Blur Buster says:

      Probably not the only one, but GT720 is the only Blur Busters confirmed one at this stage. If you want to try other projectors, you may need to be a guinea pig and test a projector’s 120Hz feature.

      Stick to projectors that support frame-sequential 3D (60Hz/60Hz for left/right), since those projectors are the ones that is likely to be able to do 120Hz (at least during 720p).

      In addition, as a rule of thumb, try enabling the projectors’ 3D mode even if just using for 2D 120Hz, since 3D mode usually reduces motion blur through a black period between frames (serves as a crosstalk reduction technique, but also reduces motion blur even for 2D). This produces further motion blur reductions above-and-beyond the increase in Hz.

    • yasamoka says:

      I have the Optoma GT750. 120Hz works natively (I have already taken photos as proof) and so does motion blur reduction (still have to collect scientific proof). The Google Maps moving image is now readable and the moving UFO can be tracked with much less blur than before. Brightness is lowered and Black levels have been jacked up.

      There are two modes, Link 3D and VESA 3D. The latter seems to have less of an impact on brightness, colors, and black levels. I have a colorimeter (Spyder4) so I will measure the impact on brightness and colors while using these modes.

      Chief (bows down), I currently have an Arduino and some photo sensors and can probably whip up an oscilloscope in a while. However, is there a way that I can use a still photos camera (DSLR) to prove that the GT750 is using Black Frame Insertion? I thought about setting a really fast shutter speed and taking multiple photos. Some should turn out bright, and others should turn out dark.

      Love your site and I would be glab to contribute to the science in here.

      • Chief Blur Buster says:

        >>Chief (bows down), I currently have an Arduino and some photo sensors and can probably whip up an oscilloscope in a while. However, is there a way that I can use a still photos camera (DSLR) to prove that the GT750 is using Black Frame Insertion?

        Thanks for the confirmation about the GT750! There are several methods:

        (1) [Easy] You can buy an entry level 1000fps camera for about $200 now. Casio EX-FC200C and Casio EX-ZR200. Also serves great general point-and-shoot cameras. It may only be low-res 224×64 at 1000fps and 224×160 at 480fps, but they are perfect for hobbyists and bloggers to analyze strobe behaviour of a display, input lag between a keypress & action happening onscreen, record the scanning pattern of an LCD/CRT, etc.

        (2) [Easy] Do TFTCentral’s camera technique for PWM. Wave the camera at a longer exposure while taking a picture of static vertical line onscreen. Motion-blur-eliminating displays (CRT, plasma, blackframe, strobe backlight) behaves like a 1-flash-per-refresh PWM (less evil than PWM dimming)

        (3) [Advanced] Although this does not directly measure strobe length, this next technique allows you to compare motion blur photography accurately between different modes of the projector: Use your SLR as a pursuit camera. See pursuit camera instructions, and use the TestUFO Ghosting with Sync Track. For a huge screen, using a pursuit camera rail won’t work, so this will be difficult. You may be able to pursuit the camera by hand, and you might succeed in a clear photograph of the “Sync Track” after approximately 20 or 30 attempts of pursuiting the camera by hand, or rotating on a tripod while taking a picture. There will be a lot of error, but you should be able to get within about ~1ms of error margin after some practice. Mathematicaly 1ms of persistence (static frame visible time) equals 1 pixel of motion blur during 1000 pixels/sec, due to the sample-and-hold effect (science papers). It’s mostly a game of making the temporal test pattern as clear as possible in the resulting photograph (the Sync Track ‘ladder’) and you know you ‘did it well’.

  5. Pingback: BENQ W7000 DLP Projector Supports True 120Hz at 720p | Blur Busters

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