Optoma HD65

The power of a projector's light output is measured as ANSI lumens (or just "lumens" for short). The brighter the projector's light, the higher the ANSI lumen rating -- and usually the higher the cost. Naturally, the brighter the room, the brighter the lamp you will need -- under 1000 lumens is adequate only in a dark room, but e.g. in a class room or a conference room you already need 1000-2000 lumens.

Resolution refers to the amount of horizontal and vertical pixels the projector uses to generate the image, i.e. the physical number of columns and rows of pixels creating the display. As a result of fixed display resolution all inputed video must be scaled to match the the resolution of the projector. Common display resolutions for a portable projector include SVGA (800×600 pixels), XGA (1024×768 pixels), 720p (1280×720 pixels), and 1080p (1920×1080 pixels).

Contrast is the ratio between the brightest and darkest areas of the image. Contrast is given ast a ratio, e.g. 800:1, and the higher the number the better the contrast. Room light has a great effect on contrast ratios, so if you plan to use projector in a lighted room, it is a good idea to pay attention to the contrast ratio. On some projector this is the dynamic contrast ratio, in which case the brightness of the picture is dynamically adjusted depending on the overall brightness of the scene.

Lamp life refers to how long the lamp can be on until it starts to become too dim for adequate use. The value is given as hours (h). Lamps on't usually just burn out suddenly, but rather dim gradually beyond usability. The poorest halogen lamps may only last for a few hunderd hours, but most lamps in use today last for a thousan hour or more. For end user, the lamp life is of great interest, as lamps are very expensive to replace.

Noise level indicates how loud the projector is, in decibels (dB). The noise is most commonly created by the fan(s) that prevent the projector from overheating.

Power consumption expresses in watts (W), how much energy the unit uses to operate.

Of the analog input alternatives, component video offers the best quality. If the digital alternatives (HDMI, DVI) are not options, then component video is the way to go. For more info please see here.

HDMI is a completely digital interfacing standard for transferring digital video and audio between electronic devices. Designed primarily with high definition displays in mind, HDMI offers a solid means of transportation for video resolutions up to 1080p. For more info please see here.

Aspect ratio is the width to height ratio of the projected image. Most often the aspect ratio is either 16:9 (widescreen) or 4:3. See more here

S-Video is an analog video transmission standard which uses a mini-DIN connector to deliver Luminance and Chrominance information on separate subchannels. Quality-wise S-video stands somewhere beteeen composite video and component video, More information in glossary.

A VGA connector (aka D-sub 15) is an analog three-row 15 pin DE-15 connector commonly used in video cards of computers, and thus it is often an easy way to connected a computer source to the projector.

Type refers to the technique the projector uses to generate the image. Possible options are CRT, LCoS (Liquid Crystal on Silicon), DLP (Digital Light Processing), and LCD (Liquid Crystal Display). of which the last two are the most common solutions today. LCD is generally thought to be the better choice for data projision, whilst DLP is preferred in video projision use. In practice, however, today the two competing types are very close to each other in quality.

Composite video transfers the video signal over a single RCA cable. Compressing all the information in to a single cable leads to losses in quality and leaves much room for improvement. Thus, altough composite is very commonly available, other connection methods should be preferred if available. For more info about composite please check out this page.

Lens shift makes it possible to move the lens up or down, left or right, while keeping the projector stationary. This way you can relocate the projected image on the wall without the need to move the projector, making it easier to place the projector to desired location. The lens shift can be operated either manually or, in some models, electronically (motorized).

Some projectors offer lens shift only vertically (up and down), some horizontally (left and right), and some both.

Keystoning occurs when a projector is aligned non-perpendicularly to a screen, resulting in an image that looksa trapezoidal rather than square. The mis-alignment can be reduced (or removed) by keystone correction, which alters the projected image to countermeasure the misalignment in shape. The correction can be done either optically (with lenses) or digitally using digital image processing.

The amount of keystone correction a projector provides varies from one model to another. Horizontal +/- presents as degrees the maximum horizontal correction the projector can fix.

The amount of keystone correction a projector provides varies from one model to another. Vertical +/- gives as degrees the maximum vertical correction the projector can fix.

The maximum size of the projected image, in inches, refers to the largest diagonal measurement with which the projector will work.

The minumum size of the projected image, in inches, refers to the smallest diagonal measurement with which the projector will work.

Most projectors have a zoom lens, allowing for the adjustment of the image size without the need to move the projector. Zoom factor expresses how greatly you can affect the image size without moving the projector, e.g. if the zoom factor is 2x you can adjust the image size by 100%. The zoom lens can be either manually operated or motorized ('power zoom').

SCART is an old analog connector/cable, which is commonly used in Europe. It can transfer both video and (stereo) sound. Supported videos are one or all of the following: composite, RGB, and S-Video.

VGA-SCART means that the projector can handle RGB signal input from the VGA port.

Vertical shift is the maximum distance the center of an image can be moved vertically (up or down) from its original position. Given as percentages of the screen height.

Horizontal shift expresses in percentages of (the screen width) how much the center of the image can be moved left or right from its original center.