Comparison Viewsonic PA503W vs Epson EB-X41

— HD (High-intensity discharge). General name for gas discharge lamps, i.e. lamps in which the light flow is created by an electrical discharge between the electrodes inside the bulb. In the case of projectors, such lamps can be mercury, metal-halide, and xenon (see above for more details).

— LED. LEDs are used as a light source. They provide high brightness with low power consumption.

— Laser-LED. Light source based on laser LEDs. It has even greater brightness than classic LED, with relatively low power consumption.

— UHP (Ultra-high performance) — a high-pressure mercury lamp, developed by Philips. Compared to other lamps, it consumes less power, while not inferior in brightness. Projectors on such lamps are smaller and lighter than conventional ones due to a smaller power supply, the cooler operates with a lower noise level. The creators claimed a service life of up to 10,000 hours. One of the most popular types of lamps for projectors today

– UHE (Ultra-High Energy). Variety of UHP lamps (see above).

— UHB (Ultra-high brightness). Another kind of UHP lamps (see above).

— NSH (New Super High Pressure). Also applies to high pressure mercury lamps manufactured by Ushio. Somewhat less popular than UHP and its peers, but also widespread. Estimated operating time is about...2000 hours.

— SHP. High pressure mercury lamps manufactured by Phoenix.

— P-VIP (Video Projector) — a high-pressure mercury lamp from OSRAM. High brightness lamps, service life — 4000 — 6000 hours.

—UHM (Ultra High Performance Lamp of Matsushita) is a high pressure mercury lamp manufactured by Panasonic. Сan be easily changed, operating time, depending on type — 2000 — 5000 hours.

— Xenon. The design and principle of operation of such lamps are similar to high-pressure mercury lamps — light is created due to a discharge in a gaseous medium. However, instead of mercury vapor, in this case, an inert xenon gas under high pressure is used. This allows to create high power lamps (from 2 kW) with the appropriate light flow. Xenon lamps are used primarily in professional models.

— HPM. High-pressure mercury lamp technology developed by Sony and used primarily in its projectors (although other brands are also available). Combines compact size and relatively low cost with high brightness.

— DC. Abbreviation for "direct current". In the case of projector lamps, this designation usually refers to mercury lamps powered by direct current. The operating voltage of such lamps in different models of projectors may be different. Their design usually uses various tricks to improve performance compared to conventional lamps of this type — in particular, increase service life and reduce power consumption without sacrificing brightness.

— AC. This abbreviation stands for "alternating current". Such lamps are similar in almost everything to the DC ones described above, differing from them only in the type of power supply.

Minimum projector lamp life as stated by the manufacturer. Specified by the total time of continuous operation. Note that if the projector was operated without violations, then upon reaching this time, the lamp will not necessarily fail — on the contrary, it can work for quite a long time. However, when evaluating durability, it is best to focus on the claimed service life.

When working in economy mode, the brightness of the backlight is noticeably reduced, on average by 30-50%. With a decrease in brightness, heat dissipation also decreases, which saves the working life of the illuminator, thereby increasing the lamp life. Thus, the ECO mode allows you to extend the lamp life by an average of 30%. If the typical projector lamp life is 4000 hours, regular use of the ECO mode will extend the backlight life to approximately 5500 hours.

The power consumption of the backlight lamp installed in the projector.

Theoretically, the more powerful the lamp, the brighter it is. However, this is only true when comparing lamps of the same type (see above); and even in this case, the brightness may also depend on the nuances of the design. Therefore, when evaluating the capabilities of a lamp, it is worth focus not so much on power, but on the directly claimed brightness in lumens (see below).

But what this parameter directly affects is the total power consumption of the projector: the lamp is the most “greedy” component of the device, compared to it, the power consumption of the rest of the electronics is very small. Also note that many powerful lamps have high heat dissipation and require cooling systems, which affects the size and weight of the projector.

The dynamic image contrast provided by the projector.

Dynamic contrast ratio is the ratio between the brightest white and darkest black colour that a projector can produce. Recall that the quality of colour reproduction and detailing depend on contrast, the higher this indicator, the lower the likelihood that details will be indistinguishable in bright or dark areas. However, dynamic contrast is a rather specific parameter. The fact is that when it is calculated, the brightest white at the maximum brightness settings and the darkest black at the minimum are taken into account. As a result, the figures in this column can be very impressive, but it is impossible to achieve such a contrast within one frame.

By introducing this parameter, the manufacturers went to a certain trick. However, this is not to say that dynamic contrast has nothing to do with image quality at all. Projectors can use automatic brightness control, in which the overall brightness, depending on the "picture" on the screen, can increase or decrease. This format of work is based on the fact that the human eye does not need too bright areas on a general dark background and very dark areas on a bright one, the image is normally perceived even without it. The maximum brightness difference achievable in this mode of operation is exactly what described by dynamic contrast.

Horizontal frequency supported by the projector.

This parameter is relevant when working with analogue video signal. In such a video, the image is formed line by line: each pixel in the line is highlighted in turn, then the next line is highlighted, and so on. The horizontal frequency describes how many times per second the backlight beam runs from edge to edge of the screen. For normal playback, the projector must support the same refresh rate as the input signal was recorded. However, most models support a fairly wide range of frequencies, and there are no problems with support. Also note that if you are not a professional, then when choosing a projector, it is quite possible to focus on the frame rate (see below) — this parameter is simpler and more intuitive, and support for a certain frame rate automatically means support for the corresponding line rate.

Frame rate, simply put, is the frame rate supported by the projector.

For normal playback, it is highly desirable that the frame rate of the projector match the original frame rate of the video signal. However, most modern models do not support a specific frame rate, but a whole range of frequencies, and quite an extensive one at that.

Note that for viewing most video materials, the range from 24 to 60 fps is quite enough. The exception is 3D content, which may require double the frame rate, up to 120Hz (see " 3D Support " for details).

The technology by which the projector sensor is built.

— DLP. This technology is based on a chip with thousands of rotary micromirrors. Each such mirror corresponds to one pixel and has two fixed positions — “lit” and “darkened”. In most DLP projectors, there is only one sensor, and the output of a colour image is provided by the colour wheel, thanks to which the projector alternately displays the red, green and blue image; they are replaced so quickly that the viewer perceives not individual frames, but a whole colour picture. Compared to LCD models (see related section), these single-sensor projectors are more compact and offer better image contrast with deep black levels (which improves black and white image quality). However, the brightness of the colour image in DLP devices is relatively low, in addition, they are subject to the "rainbow effect": in dynamic scenes, colour artifacts may be noticeable due to the mismatch of red, green and blue image components. Three-sensor DLP projectors don`t have these shortcomings; however, such a design is very expensive, so it is found rarely, mainly among premium devices.

— 3LCD. Technology based on the use of translucent LCD sensors. There are three such sensors, each of them is translucent with its base colour (red, green or blue), and the final colour “picture” is formed from three images simultaneously superimposed on each other. Thanks to...this format of operation, you can achieve brighter, more saturated colours than in single-sensor DLP projectors (see the relevant paragraph); in addition, this technology is completely devoid of the "rainbow effect". Among its shortcomings are the relatively low contrast ratio (in particular, due to the low black depth) and the larger size of the projectors.

— LCD(Liquid Crystal Display) — a colour rendering technology based on the modulation of light by liquid crystals. Do not confuse LCD and 3LCD sensors. 3LCD technology forms an image from three separate light streams, and in an LCD sensor, the image follows immediately from a single light beam. Sensors of this type provide a stable, contrasting and colour-rich image. Among the shortcomings of the technology, one can note the glimpse of the light grating, if you look at the picture from a close distance. Additionally, the substrate of LCD sensors is prone to fading, due to which the blue colour may begin to turn yellow over time (note that this can happen after a long time of active operation). LCD sensors require periodic maintenance, the service comes down to cleaning the air filter. LCD-sensor projectors are usually compact in size and light in weight, such models are prone to heat, and the noise threshold is above average.

— LCoS. A technology that combines the properties of DLP and LCD. Like LCD, it provides three separate sensors for the three primary colours (red, green, blue), and the final colour image is formed by the simultaneous superposition of these three components. The difference lies in the fact that in LCoS projectors the sensors are not translucent, but reflective. Thanks to this, you can achieve excellent contrast (as in DLP) combined with bright, high-quality colours without the "rainbow effect" (as in LCD). The main drawback of this technology is the impressive cost, which is why it is used mainly in premium projectors.

The size of the sensor affects the depth and final quality of the image. The larger the sensor, the more light it is able to process, which means the picture will be clearer and more structured. The average projector has a sensor of 0.5-0.7″, advanced projectors use sensors of 1.2-1.5″ and more.