How to choose a home theater projector

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April 7, 2021, 19:45

We live in the wrong time to go to the movies. However, the cinema experience can be recreated at home. A TV, no matter how big and high-quality it is, will not give you the desired sensations. Another thing is the projector.

Over the past few years, projectors have gotten noticeably better. This is especially true for devices designed for short distances (ultra short throw). Such projectors can be placed very close to the wall, so they do not need special fasteners or tripods. The rise in popularity of ultra-short throw projectors is driven by falling prices for laser backlight technology. Lasers are much better than lamps because they shine brighter and last longer — up to 30 thousand hours instead of 6 thousand. This is the equivalent of ten years of continuous operation.

Also, the projectors become brighter and clearer. But most importantly, they are significantly cheaper. Today, for about a thousand dollars, you can get a projector that can project a 4K image onto a 150-inch diagonal. For the same money, you can buy a 65-inch TV, but the image on it will be half the size.

Here are a few key parameters to consider when choosing a projector

LCD and DLP technologies

Projectors generally use two types of technology: LCD and DLP. These are fundamentally different systems, with their own advantages and disadvantages.

Most projector manufacturers today use the technology DLP (Digital Light Processing). They use digital light processing units made almost exclusively by Texas Instruments (TI).

The heart of a DLP projector is an optical semiconductor chip called a “digital micromirror device” (DMD) that contains millions of aluminum mirrors. Each such mirror corresponds to one pixel of the created image. The micromirrors are movably fixed on the matrix substrate and can almost instantly deviate into one of two positions — towards the light source (on) or away from it (off). Mirrors can change position up to 5000 times per second.

Most budget projectors like the BenQ HT3550i use a 0.47″ DMD chip, while higher end models like the Samsung Premium LSP9T use a 0.66″ chip. Both use mirrors that tilt +12 and ‑12 degrees for white and black, but TI recently introduced a new 0.47-inch 4K DMD chip with +/-17 degrees of tilt, which should improve picture brightness and contrast.

DLP projector manufacturers include Optoma, LG, BenQ, and Panasonic. The advantages of DLP technology are portability, high contrast ratio, less fringing and lower cost of projectors, especially in the 4K and short range segments.

The biggest disadvantage of DLP technology is the rainbow effect. These are bright red/blue/green artifacts that sometimes appear in an image and affect some viewers more than others.

In projectors based on technology LCD, a prism is used to separate the light source into red, green, and blue beams. These beams pass through LCD displays with an image, and then are combined into one stream through a second prism.

The main manufacturer of LCD projectors is Epson, along with Sony, Sanyo and others. LCD projectors offer better sharpness and more accurate color reproduction, but have lower contrast ratios and may experience degradation in image quality over time. They also cost significantly more than DLP projectors.

Features of ultra short throw projectors

In the last couple of years, ultra-short throw projectors have become very popular. Mainly because of the ease of handling. You can place the projector on a bedside table at a distance of 20 to 50 cm from the wall, and get an image with a diagonal of up to 120 inches on the same wall. This is much easier to do than mounting an old-fashioned long-throw projector under the ceiling.

Ultra short throw projectors use very durable lasers that do not need to be replaced. Finally, the laser beam does not need to be focused, so the picture is clear immediately and without any adjustment.

But there are also nuances that are important to know in advance. First, the screen on which the image is projected must be absolutely flat. Since the projector directs the laser beams almost parallel to the wall, any bumps or roughness will introduce severe distortion into the picture. For the same reason, you cannot use the usual roll screens — they inevitably have a small “wave” on the surface.

For best results, especially when there is a lot of ambient light, it is recommended to use an Ambient Light Rejecting (ALR) screen. ALR screens have microscopic “flakes” that reflect projector light to your eyes but absorb ambient light. Some projectors, including models from Epson and HiSense, come with ALR screens. But if you decide to buy such a screen separately, it will cost you an additional $500.

Brightness and Contrast

Home theater projectors typically have 2,000 to 4,000 lumens of brightness, but claims should be taken with a grain of salt. Some models can actually put out 3000 lumens or more, but this is not good for lamp life. Also, some manufacturers tend to exaggerate the maximum brightness.

One way or another, when buying a projector, you must understand that the image will be less bright than that of a TV. For example, a bright TV screen can deliver 1000 nits of brightness. But the brightest projector will only deliver 100 to 150 nits of screen brightness. This is because projectors are by default designed for use in dark or at least slightly darkened rooms.

The contrast on the projectors is also significantly different from the television. Unlike OLED TVs, projectors are not able to produce a zero light level in a particular area of the image due to ambient light and reflections. So even on the most contrasting projector, the black color will be more like “conditional black”, as we see it on LCD displays of TVs and monitors.

Some projectors try to compensate for the lack of contrast by dynamically adjusting the image. To emphasize the dark areas of the picture, they highlight the light ones. But after such a “pumping”, scenes with moderate contrast may seem faded, which is why not all users like this feature.

Short conclusion — count on using the projector in the dark, no matter how bright it is.

Mounting and noise level

An important advantage of classic long throw projectors is that you can mount the projector on the ceiling with little to no space in the room. If you decide to go down this path, then along with the projector, buy the appropriate hardware, and also think in advance how you will bring the necessary cables to the necessary cables.

Keep in mind that a lightweight projector is easier to mount. DLP models tend to be lighter than LCD models.

Monitors and TVs do not make noise. But the projector can be quite noisy as it has an active cooling system. The brighter it is, the stronger the lamps glow. And, accordingly, the more intensively the cooling fans spin.

HDR and resolution

Not every 4K projector has a true 4K sensor. There are many relatively inexpensive DLP projectors that simulate 4K resolution using a pixel shift system. This system emits each pixel four times, moving it to adjacent positions to create a 4K image. The shift occurs in less than 1/60 of a second. Thus, the same number of pixels appear on the screen as in the case of an “honest” 4K resolution. At the same time, visually, the pictures are almost indistinguishable.

Epson LCD projectors with “4K enhanced” technology also have native 1080p resolution, but the pixels are shifted twice.

If you really want to get “honest” 4K, you have to pay for it. Some of the cheapest projectors with full 4K chips are Sony’s VPL-VW295ES and JVC’s DLA-NX5. Both start at $5,000.

HDR also works very differently on projectors than it does on TVs. As already mentioned, projectors cannot provide the desired brightness on the display. Therefore, they use a technique called “tone mapping”. To do this, the entire HDR gamut is shifted to a lower brightness range.

For this reason, almost all projectors only support HDR10. None of them support Dolby Vision and only a few models work with Samsung’s HDR10+.

Optics

When installing a short throw or long throw projector at a distance of one and a half to eight meters from the screen, it is important to take care of the lens shift function. This will provide a decent zoom range and make it easier to position the projector in the right place with the right screen size.

Lens shift also helps when the projector is mounted higher or lower than the manufacturer’s recommended distance from the screen (or any horizontal distance from the center). In this case, the image will be trapezoidal, but the lens shift will allow you to optically correct it.

Otherwise, digital correction may be required. It digitally stretches or compresses part of the image, but this leads to noticeable distortion or pixel artifacts. So lens shift is much preferable.

Games

Finally, if you want to use the projector for gaming, pay attention to the refresh rate and input lag figures. Some newer projectors from Viewsonic, Optoma, and others deliver up to 240Hz and latencies as low as 4 or 5 milliseconds.

Keep in mind that many popular home theater projectors are not suitable for gaming due to high latency and low frequency.

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