25th May 2018
Promoted by
BenQ
Want something bigger than a TV but don’t know where to start? Here’s what to look out for when buying your first projector.
As an alternative to the television, projectors have long held a reputation for being expensive and complex. In their earliest days, when projectors relied on bulky and energy intensive CRT technology, this was often the case. But with the advent of DLP and LCD technologies, the projector has become an increasingly popular option that anyone can use, offering far larger screen sizes (100-inches and above) than possible with a standard LCD or OLED TV.
The difficulty has been finding a projector that can keep up with the latest 4K UHD TVs—which boast four times as many pixels as a full-HD 1080p TV or projector, more vibrant colours and deeper blacks—at a reasonable price. The first consumer 4K projectors hit the market at an eye-watering £25,000. Those have since dropped to £5000 at the low end, but that's still far above the price of even an OLED TV, where prices are as low as £1500 if you time it right during sales.
Fortunately, the first truly affordable 4K UHD projectors are now appearing, spearheaded by models like the BenQ TK800, which sports both a 3840x2160 resolution and high dynamic range (HDR) capabilities for a reasonable (comparatively speaking) £1200. You get a far larger screen than a TV for the price, upwards of 100-inches in the case of the TK800, which is better for cinematic viewing with friends, while the portable nature of a projector means it's easy to get set up in the garden on a weekend (UK weather permitting, of course).
Affordable 4K projectors are made possible by a bit of clever engineering using DLP (digital light processing) chips, which power many of the best projectors. For the first time in a long time, it's possible to look beyond the familiar flat-panel TV when kitting out a cinema setup—especially if you want a truly cinematic experience.
What's a DLP?
There was a time when projectors used three separate light sources for red, green and blue light, requiring professional calibration to get those beams to line up on the screen. The introduction of single LCD technology greatly simplified many aspects of set up, which carried over to the popular DLP systems used by many modern projectors (especially in digital cinemas) today.
At its heart, the modern projector differs little from film-based cinema projectors of old. There’s a light source that illuminates an image that passes through a series of lenses to make it bigger. The difference is that the modern projector uses brighter, more efficient light sources and replaces the film-based image with either a translucent LCD or a DLP chip. A third technology, LCoS (liquid crystal on silicon), is a hybrid of LCD and DLP technologies and has many benefits—not least of which is superb contrast levels for richer colours and blacks—but is uncommon and expensive.
If you're shopping for a reasonably priced projector, its LCD or DLP that you'll encounter. An LCD projector uses three liquid crystal panels, each tasked with creating a red, green or blue image, which are then combined so you see a full colour image. LCD projectors generally feature excellent black levels, but can suffer from panel decay over time, resulting in weaker colour reproduction.
DLP works differently. A DLP chip is made up of microscopic mirrors on a semiconductor chip known as a Digital Micromirror Device (DMD). Each mirror can be flipped on and off individually, either directing light towards or blocking it from the output lens (each mirror is effectively a pixel). Colour comes from a spinning Red, Blue and Green colour wheel, which sits in front of the light source. This gives DLP projectors a much higher pixel “fill factor” than transmissive LCD, resulting in better colour reproduction and sharper images. The use of a colour wheel means some DLP projectors suffer from the "rainbow effect", where brief flashes of red, blue, or green shadows accompany moving objects, but modern projectors perform far better in this regard.
Given how mature the tech is, why, then, has it taken so long for affordable 4K projectors to appear? The issue is one of miniaturization. Almost all 4K TVs use 3820x2160 individual pixels to create an image. Doing the same for the tiny LCD or DLP chips used in projectors is a costly proposition. While some 4K projectors do feature all 3820x2160 pixels, others like BenQ have come up with a neat way of using existing DLP chips more efficiently.
At the heart of affordable 4K DLP projectors like BenQ's TK800 is an innovative DLP engine based on Texas Instruments' latest 4K digital micromirror device. This single-DMD solution uses TI’s clever eXpanded Pixel Resolution (XPR) technology with 4-way optical actuator—along with a process known as pixel shifting—to enable a 4K resolution, all from a 0.47-inch 1920x1080 DMD. The result is an effective 4K image at a fraction of the cost.
Pixel shifting works by taking a 1080p DLP chip and firing an image from it twice in quick succession. The second firing shifts the image by half a pixel, effectively doubling the resolution to create a 4K image. The technique works surprisingly well. Pixel doubling happens so quickly that your brain combines it all into a single, high-resolution image. Don't forget that image quality is more than just resolution, with support for HDR being particularly important, alongside higher light output, better optics, higher contrast ratios and lower noise.
Why a projector instead of a TV?
The most notable reason for buying a projector instead of TV is simply screen size. Old CRT TVs were limited in size by the sheer bulk of the cathode-ray tube, resulting in a practical limit up to around 30-inch screens, with as much depth behind the box to somehow hide in the living room. Early flat-panel LCDs lost the big-box problem but had similar screen size restrictions, this time due to manufacturing constraints like the dreaded stuck pixels, and were often accompanied by poor refresh rates and limited viewing angles.
Today it’s easy to find good TVs around 40- to 60-inch size below £1000, although cheaper sets still struggle with wide-colour coverage and off-axis visibility. Go beyond 60-inches though and the field starts to thin considerably and prices rise quickly.
Using a video projector is far more cost effective. Displays measuring 100-inch and up on the diagonal are common, often at a short throw distance of around three meters or less. Throw distance tells you how far away from a wall or screen you have to place your projector to create a particular picture size. The shorter the throw distance, the closer the projector can be while still creating a big image. It’s easy to work out throw distance by taking the width of the screen you’re trying to fill and then multiplying that by the lowest figure in a given throw ratio. But most manufacturers are nice enough quote a distance and size these days without the need for unwieldy sums.
There's still the issue of positioning a projector of course, with the ceiling as the traditional solution. However, today's compact and lightweight projectors mean this isn't essential. Short-throw lenses allow projectors to sit on a coffee table with the minimum of fuss. Once placed down, getting the picture square and uniform from any chosen position is simple enough thanks to keystone correction. This compensates if the projector is at an angle to the wall, ensuring you get a perfectly straight picture instead of a wonky trapezoid—look for automatic setup on better models.
There's another good reason to choose a projector over a TV, which is all down to the way our eyes deal with light. Whether it's CRT, plasma, LCD or so-called LED, each of these display technologies is defined as "emissive", meaning they involve beaming artificial light directly into the eye. Projections, on the other hand (whether it's a film projectors or a digital one), bounces light off a reflective surface (known as "transmissive")—the same way we see almost everything else in the world around us. Viewing angles are rarely a problem with projected video and the picture is often found to be more relaxing on the eye.
The downside is that a lot of light is lost in the process of bouncing it off a surface, meaning projectors tend to work better in darker rooms. However, so long as you pick a projector that has at least 2000 lumens of brightness (ideally 3000) you shouldn't have to sit in total darkness to get a decent picture.
But what about those expensive bulbs?
First-time users tempted by the possibilities of modern video projectors shouldn’t be too concerned by the need for dedicated projection screens, nor by mooted high running costs from consumables like replacement bulbs. Given the BenQ TK800's excellent beam output—3000 ANSI lumens—any light, matt-finish wall in the home is all that's required, although special projector paints and dedicated screens improve contrast and brightness.
Look out for something called "screen gain" when making a purchase. The higher the number, the more reflective the surface, resulting in a brighter image. Higher gain isn't the right solution in every situation, though. As always, there's a trade-off, with narrower viewing angles and colour shifting affecting some high-gain screens. Always check reviews online!
On the bulb side, today's mercury-vapour bulbs are reliable and the advertised lifespan can be a decent 4000 hours under best-performance Normal mode operation. This can extend to 8000 hours in Smart Eco mode (even as far as 10,000 hours in full Economy mode). Built-in lamp timers help you monitor usage under all these conditions, so you can see when the time comes to get a new bulb. Even used for four hours a day, overall run-time is likely several years, with running costs for a drop-in bulb amounting to just a few pennies a day.
There are alternatives to the bulb, including LED or laser projectors. These offer longer lifespans and sometimes other benefits like a greater overall brightness, but often cost significantly more to buy in the first place.
For anyone not already familiar with the joy of larger-than-life video across the wall, the new range of 4K UHD projectors represents a turning point in home entertainment that should not be missed. And now at a new price point below £1200, projectors like BenQ's TK800 show how 4K cinema at home is now entirely within reach.
