Of the Luminous flux determines how powerful the image from the projector can be projected onto the screen. The lower it is, the darker the environment should be. The maximum luminous flux is stated in the product data of the projector, but in normal operation only two thirds or half of it is often achieved. 3,000 lumens and more are a very good value, even with a luminous flux of 2,000 lumens you can still use the projector in daylight. From around 1,500 lumens it should at least be twilight.
LED projectors cannot match the color brilliance of an OLED screen, for example. High-quality devices create around 85 percent of the DCI-P3 color space area that is relevant for HDR content, but often only 74 percent coverage is common. At least the standard sRGB color space should be fully covered.
Native UHD projectors, like those found in cinemas, are large and expensive. That’s why the developers at JVC have chosen an inexpensive one for home cinema projectors upscalingdevised a trick that many manufacturers now use: they place a vibrating pane of glass in the beam path between the DLP chip or LCD panel and the lens. Each image is thus projected diagonally shifted by half a pixel, together they are perceived by the sluggish human eye as a quasi-UHD image.
JVC calls this technology “4K E-Shift”, the manufacturers of DLP devices speak of “XPR-Shift”, and LCD projector manufacturer Epson calls it “4K Enhancement”. The increase in resolution is indeed visible. Projectors with a native resolution of 2,716 by 1,528 pixels do this particularly well, because a single shift is sufficient to double the resolution to Ultra HD. 4K projectors that work natively with Full HD resolution need more than one shift to produce a UHD image. Technically, the upscaling is now well advanced and produces a very good image on the screen. However, the native 4K resolution still looks sharper and more vivid.
Regardless of which lamp technology the projector uses: waste heat always arises. The size of the fans required is limited, especially with compact designs – and small fans usually make more noise. As long as the film sound is playing, you can usually not hear anything, you should only not sit directly next to the projector during quiet film passages. The sound level for most devices is between 30 and 40 decibels in normal mode, and of course slightly lower in eco mode. This corresponds to whisper volume or normal environmental noise. Above 40 decibels are annoying.
Many projectors have built-in ones speaker, usually two pieces with 5 or in the best case 10 watts of power. However, you shouldn’t usually expect more than an understandable message tone here. Home cinema lovers will connect an external sound system.
The connections for the source devices such as Blu-ray players or game consoles are the same for most devices: There are usually HDMI interfaces for this, although you should pay attention to the standards here – i.e. at least HMDI 2.0 and the copy protection HDCP 2.2, so that You can play UHD Blu-rays and stream certain content. Other elements include audio interfaces, USB, component input and LAN network connection. WLAN and Bluetooth audio are also becoming more and more widespread. Support for 3D content was in high demand for a while, but as with televisions, it’s already passé
If you want to mount your projector permanently, the “overhead method” is a good idea: The device is attached using a special mount hung from the ceiling, mostly upside down. You can then adjust this position in the menu so that the image is displayed the right way round. With compact devices, a tripod nut like on the camera makes sense, so that you can also mount it on a photo tripod, for example. You also need a sufficiently long connection cable. Or you rely on a wireless HDMI set for wireless image transmission – but then it will be significantly more expensive.
To the correct orientation of the image on the screen, an optical lens shift in the horizontal and vertical direction makes sense. Many home theater devices have it. You will also find a grid test image in the projector’s menu, which makes alignment easier. Only if there is no other option should you use the keystone correction that is also offered by all devices. This function degrades the resolution and the projection appears blurred. The automatic alignment and focusing of the projection is becoming increasingly popular, especially for mobile devices with frequently changing locations.
The projection ratio, the quotient of distance and image size, tells you how far the front lens of the lens has to be from the projection surface for a certain image size. For example, with a ratio of 1.2, the distance for a one meter wide image is 1.2 meters. If two values are given in the technical data, it is a zoom lens.
In the beginning, a white wall is sufficient for the projection, but in order to be able to really use the quality of your projector, you should use a better one if possible projection surface deploy. A good screen costs more than 200 euros – a built-in motor makes the whole thing even more expensive. However, with mobile projectors it can be quite attractive to try out completely unconventional projection surfaces, especially if the focus is on fun and not on image quality.