Posted on March 26, 2018 By Art Feierman
Viewsonic PX727-4K 4K UHD Projector Review – Special Features: 4K UHD, 4K HDR, Silence Mode, REC 709 vs P3/BT.2020, Color Wheel and Rainbow Effect
Last year TI – Texas Instruments – started shipping a 4K UHD chip to their projector partners (that chip is 2716×1528 pixels, times 2) because it pixel shifts one time. That doubles the 4.15 megapixels up to 8.3 megapixels, the requirement to call a projector “4K UHD.” Now, regular readers of this site know we have an issue with “4K UHD” and wish it was simply UHD. We find the 4K misleading, as we believe that you want true 3840×2160 native resolution – which is to say, pixel sizes half that of those 4K UHD projectors.
The PX727-4K is a different, slightly lower resolution as mentioned above. Like the Epson and JVC 1080p pixel shifters, its native resolution is 1920×1080, but it pixel shifts hitting the screen 4 times, not the usual twice, so it’s 2 megapixels x4.
It means that the PX727-4K has pixels physically (relative to screen size) that are much larger than the earlier DLP 4K UHDs and dramatically larger than a true 4K projector.
The Viewsonic is the 5th of the “lower resolution” 4K UHD projectors to visit my home theater. Like the others, the Viewsonic isn’t exactly loaded with features – it mostly resembles $600 – $800 home entertainment projectors with, of course, the addition of being 4K content capable! Here’s more explanation of this projector’s 4K UHD as it compares with other 4K capable projectors:
4K UHD standard says a projector needs to put 8.3 million pixels on the screen to be 4K UHD. Sadly, the CTA standards folks (that’s the organization that puts on the CES trade show), did not specify how large those pixels can be, so they allow “pixel shifting.” That is, starting with panels or chips that have less pixels than 8.3 million. Some 4K UHDs have panels/chips with 4.15 million pixels – 2716 x 1528 x2 native resolution – and fire them twice, shifting position diagonally so that the second firing overlaps the first. Typical of those projectors are BenQ’s higher-end models, and some models from Optoma, Acer, Vivitek, and so on, although so far Viewsonic is sticking to the less expensive PX727-4K, and its brighter sibling the PX747-4K.
Then, there are the newer, lower cost 4K UHD projectors like the two new Viewsonics which have 1080p panels, just like most of the home theater projectors sold in the last 8-10 years. The difference between these and “most of those” is that these are also pixel shifters, but they fire each pixel 4 times, each overlapping the others. So, their native resolution looks like 1920 x 1080 x4. That, too, works out to 8.3 million pixels (just over 2 million times 4).
Overlapping pixels can increase detail, but do understand that each pixel in diameter on this Viewsonic is 4 times the area of one pixel on a real, native 4K projector, like those Sony offers starting at $4,999.
Even the higher-res 4K UHDs have pixels twice the size of those true 4K projectors. So, when it comes to max detail, think this way: Pixel size is still the most important thing. When considering the different pixel sizes, native 4K (3840 x 2160) think of a baseball, for the 2716 x 1528 x2, think of a softball, and for these 1920 x 1080 x4 projectors, think of something slightly smaller than a soccer ball a six inch diameter ball (about 6 inches diameter).
It is worth noting that below this “resolution” 4K UHD are the 1080p pixel shifters that only hit the screen twice (from Epson, JVC, etc.), they too accept 4K content, but can’t put 8.3 million pixels on the screen.
Bottom line: To a large degree, the differences between all four, 4K capable “resolutions” are slight, with each step up providing some improvement. Remember, how well each projector implements, matters. Sony, for example, has 5 native 4K projectors, but the more expensive ones have better optics, etc. So, it comes down to how well each projector is implemented. Epson, for example, is the lowest res (along with JVC), but has some impressive image processing. BenQ’s high end has better optics than you can expect from all the $1,500 to $2,500 4K UHDs, etc. Naturally, we’ll discuss the actual sharpness performance of the PX727-4K on the Picture Quality pages.
4K UHD projectors (most of them), and for that matter, most projectors that can accept 4K content, support HDR – High Dynamic Range – (not all on the business projector side, and even one home theater projector I can think of lacks HDR support).
HDR is a challenge for most LCD TVs and home projectors because it calls for a lot of brightness, so there’s more range between black and white – less compression of the original scene.
With the possible exception of Sony’s $60,000, 5,000 lumen 4K projector, the VW5000ES, everything else out there definitely needs more lumens. That Sony produces over 4,000 lumens in best quality modes, whereas most of these produce 1,500 lumens or less in their best modes.
Projectors (and many LCD TVs claiming HDR) can’t really do the full HDR, so they compromise. This first year, the compromises have been very different from one projector to another. Usually, the tendency of not having enough brightness is that mid-range bright objects are too dark, or as I sometimes say, “too dim.” One can correct for that, but doing so effectively also reduces the key advantage of HDR – a more dynamic picture.
The PX727-4K does about as good a job as any of these lower 4K UHD projectors when it comes to HDR. This is also a place where we see a differentiation between the PX727-4K, and, say, the BenQ HT2550. Color controls differ, therefore so will the end result on your screen. The Viewsonic offers two controls that affect HDR content. Eric writes more in detail on the performance page, so I won’t go into it here. Eric likes a Low setting on EOTF, and 2.2 Gamma, while I went up to the Medium EOTF setting – raising up the midrange even more in brightness, but partially compensating by setting gamma to 2.3, or even on occasion, 2.4. I was sufficiently pleased with the results on HDR content like Valerian and Passengers.
This Viewsonic PX727-4K has a Silence picture mode. The first time I encountered a Silence mode like this, it was on the BenQ HT2550 – surprise. Silence mode must be one of the options available from TI (the makers of the DLP chips and much supporting technology). What does it do? It makes the projector run at its very quietest, which isn’t much different than Eco mode, as far as fan noise. But, one thing I’ve noticed is that all that pixel shifting makes a good bit of noise, basically a not very quiet hum. That goes away in Silence. Silence puts the PX727-4K into a simple 1080p mode – no pixel shifting. Pixel shifting adds some noise, much as color filter wheels do, or dynamic irises. I am noticing that these lower res 4K UHD DLPs that pixel shift 4 times, are definitely louder than the more expensive ones with the higher-res 2716x1528x2 chip, which apparently makes less noise since it only has to shift one time, not 3 times.
It looks like selecting Silence mode is the only way to turn off pixel shifting. When you do that, you have, essentially, a classic 1080p projector. In other words, a projector worth half the price. Other than playing with it for a few minutes, I didn’t use it. I used other modes and let the projector pixel shift 1080p and other “lower” resolutions. When I want quiet, I make sure I’m in Eco mode.
Of course, Silence mode would make sense if you are watching 1080 resolution content, although I’ll stick to a calibrated mode for that. Might be something to do (calibrate a Silence mode), if you get a chance.
If, however, you desire 1:1 pixel mapping for the sharpest natural image from the data, go for it. The whole point of pixel shifting is that by using more pixels, it can more closely behave like a projector using smaller (higher native resolution) pixels. In a sense, by using Silence mode, you are making the PX727-4K perform sharpness and detail wise, like Viewsonic’s sub-$800 basic 1080p models.
To take full advantage of the 4K suite of standards, it’s not just the 8.3 million pixel requirement, but the ability to do both HDR, and also a larger color space. There’s BT.2020, which is the maximum, but I don’t even think the cinema projectors in you local theater have enough range to fully do BT.2020 (which gives richer, more intense, and more colors to work with).
That’s okay, there’s a “subset” called P3. I hear engineering types refer to it as “P3 in a BT.2020 wrapper.” These days, P3 expanded color is obtainable, although lamp based projectors generally can’t get close, (they rarely even get to the full REC709 but get very close, the standard we’ve been using for the past couple of decades). Expect what is probably around 95% of REC709. Far better equipped to do P3 are laser projectors, or LED projectors (like BenQ’s HT9050 which supports P3). Those laser projectors trying to do P3 are doing it, or at least, apparently getting very, very, close.
Some lamp projectors talk the BT.2020 / P3 game, but best they can do is take all the BT.2020 info and convert it down to REC 709, surrendering all the advantages that BT.2020 promises. BenQ mentions BT.2020, but, ultimately, they also say they have great color, which achieves 96% of REC 709 (which is probably no more than 70% to 75% of P3, if that).
That is exactly what this Viewsonic does – reads the P3 info, converts to REC 709. Bottom line: You essentially get REC 709 color. There may be some minor advantages, but the real trick is to have the much larger color space so a projector can reproduce all the same colors your local high-end cinema projector can produce, when you plunk down that $10+ for a ticket.
The Viewsonic knows what to do with BT.2020/P3 – it reduces it REC709, even when the content on disc, or download, or other 4K source, provides the BT.2020 color space.
In that regard, it’s about the same as just about all of the lamp based projectors around this price range.
There’s an exception – Epson’s 5040UB ($2,699 list). It adds a cinema filter, which helps, in its best mode. Epson, therefore, does a lot better than the rest (or at least all those we’ve worked with), but – and I mean a big but: that cinema filter eats up about half of that Epson’s lumens, reducing it to about 1,000 lumens. That’s roughly 20% less brightness than this Viewsonic, calibrated for handling 4K, HDR, etc. That’s the trade-off: The Epson can get closer to P3, but it has less lumens doing so, which means more compromise when doing HDR, but then, remember while the Epson is an extra $1,000 and change, its real strengths that make it so popular are elsewhere.
Bottom Line: The PX727-4K looks really good on HDR (HDR setting 2 preferred) but the color space, as with most of these projectors, ends up basically the same as the 1080p projectors we’ve been using all along. In other words, expect to enjoy some of the benefits of HDR, and of course 4K content, but don’t look for improved color space. On the bright side, the Viewsonic calibrated really well. More on that on the picture quality and calibration pages.
Folks, I’ll remind you again: There are always compromises!
A fast color wheel! Outstanding. Like the BenQ equivalent, this Viewsonic produces a minimal rainbow effect (RBE) that I can see, being one of the unfortunate few (5% of people?) that are sensitive to it. I’ve said this over the years that BenQ, in particular, normally puts a faster (better) color wheel in than the competition, and it’s still true. No surprise, then, that another projector coming out of Delta, would also have a faster wheel. Works for me!
These projectors with faster color wheels provide a real bonus for those of us who are rainbow sensitive (that’s called RBE). I’ve never seen info as to what percent of the population is sensitive to them, but my best guess is around 5% maybe 10%, max. So, it’s likely you won’t be, but if you have a bunch of people watching with you, someone is likely to be sensitive.
I am one of those, so with single-chip DLP projectors, I will see occasional flashes of color from time to time, with the frequency, and the amount of distraction dependent on the speed of the wheel (and also the type of content – a fast moving white object on a black background is perfect for seeing “rainbows”).
No matter. With this projector, rainbows for me are rare. Shaking my head, I can force rainbows. But not doing so, I might even get through a whole movie without seeing one (unlikely), or perhaps a few flashes on a few “ideal” scenes for spotting them. That, I can live with (and have in the past). I would no longer consider personally buying any home projector with slower wheels. for me, a lot of rainbows is a deal breaker.
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