How to Buy a Used Home Cinema Projector

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How to Buy a Used Home Cinema Projector

Projectors are a great alternative to flat screen televisions for impressive, cinema style home viewing. Modern projectors are capable of sharp, clear images, and the picture can be far larger than that of even the largest television.

Choosing a Used Home Cinema Projector

The various decisions involved in choosing a used home cinema projector involve factors such as type, resolution, aspect ratio, brightness, size, and weight. Each of these factors affects how suitable the projector is for home cinema use.

Type

There are two basic types of projector - LCD and DLP. Each uses a different type of display technology to project the image. A third type, LCoS, is less common but has several advantages over both LCD and DLP. The table below outlines these different projector types.

LCD (Liquid Crystal Display)

LCD projectors contain three LCD glass panels, coloured red, green, and blue. Light is split using a prism and passed through these panels, and then individual pixels in each panel can either be opened or closed to build up an image. The image is modulated through another prism, magnified, and projected.

Advantages of LCD projectors include superb colour saturation, sharp resolution, and light efficiency.

Disadvantages of LCD projectors include pixilation, washed out blacks, and lack of contrast. These drawbacks can seriously affect picture quality, though newer models are greatly improved in comparison to older projectors. With time LCD panels may also degrade.

DLP (Digital Light Processing)

DLP projectors contain a single chip, which has numerous miniscule reflective mirrors which correspond to the pixels. Light is projected onto the chip through a spinning red, green, blue, and white wheel. The mirrors move with the wheel and turn the pixels on and off as required, modulating the colour of the image that is projected.

Advantages of DLP projectors include excellent contrast and blacks compared to LCD projectors. This makes DLP projectors popular for home cinemas. The white component of the colour wheel increases brightness. DLP projectors are also typically more compact than LCD projectors.

Disadvantages of DLP projectors include reduced brightness and colour saturation due to the white section of the wheel. Newer models have better colour saturation. A particular problem for some people with DLP projectors is the rainbow effect, which refers to colour separation of the reds, greens, and blues. This can cause varying levels of distraction and sometimes eyestrain, though successive models have speeded up the spinning rate of the colour wheel, minimising these problems.

LCoS (Liquid Crystal on Silicon)

LCoS projectors combine elements of LCD and DLP technology. Like LCD, LCoS uses liquid crystals. Like DLP projectors, it also uses a reflective substrate. Light is either passed through the liquid crystals and reflected from the mirrors or blocked, and this modulation builds up an image. Three chips - red, green, and blue - modulate the light and there is no wheel as in DLP.

LCoS combines the advantages of LCD with those of DLP. Projectors typically have excellent resolution and colour contrast. Problems such as the screen-door effect and rainbow effect are not an issue.

LCoS projectors are not produced in the same volumes as either LCD or DLP projectors. Though popular amongst serious home cinema enthusiasts, they remain a specialist type of projector and tend to be expensive. LCoS projectors are also typically larger, heavier, and less compact or portable than other types.

The problems associated with LCD and DLP projectors should be carefully considered when purchasing an older used projector, and checking product reviews of particular models may be helpful here. They are not so much of an issue with recently manufactured projectors.

Resolution

As outlined above, the type of display technology used for the projector will affect its resolution. The resolution given in the specification is known as the native resolution. It refers to the actual number of pixels which make up the picture. For example, a projector with a 1280 x 720 resolution has 1280 columns and 720 rows, making a total of 921,600 pixels. A higher pixel number indicates higher resolution. Resolution can also be enhanced using compression technology to provide sharper pictures. The various resolutions available are named, as outlined in the table below. For home cinema use, it is recommended that a projector is used that matches the source resolution (the DVD or other media) as closely as possible.

SVGA

800 x 600 pixels

Relatively cheap and low resolution entry level projector.

WVGA

854 x 480 pixels

Relatively cheap and low resolution. Also known as 480p.

XGA

1024 x 768 pixels

Fairly inexpensive, popular resolution compatible with most computers.

HD2

1280 x 720 pixels

Mid-range projector for home cinema use. High definition (HD) ready. Also known as 720p.

WXGA

1280 x 800 pixels

Mid-range widescreen projector.

SXGA+

1400 x 1050 pixels

High quality resolution providing excellent detail.

UXGA

1600 x 1200 pixels

High quality resolution.

HD

1920 x 1080 pixels

True high definition (HD) resolution popular for home cinema use. Also known as 1080p.

2K

2048 x 1080 pixels

Superb quality resolution. Very expensive.

4K

4096 x 2160 pixels

Superb quality resolution. Very expensive.

Aspect Ratio

The number of columns and rows also corresponds to aspect ratio, which is the width to height ratio. Projectors have aspect ratios ranging between the shape of a computer monitor, which is 4:3, and that of a widescreen television, which is 16:9. The primary use of a projector will influence which aspect ratio is most appropriate. While business or academic lectures are best suited to a 4:3 projector, widescreen 16:9 projectors are better for home cinema use. 16:10 projectors are also sometimes used. It is possible to use other aspect ratios in projectors, but this can stretch or crop the picture so is not recommended for the best picture quality. The table below shows how aspect ratio corresponds to resolution, with aspect ratio given in the far right column.

SVGA

800 x 600 pixels

4:3

WVGA

854 x 480 pixels

16:9

XGA

1024 x 768 pixels

4:3

HD2

1280 x 720 pixels

16:9

WXGA

1280 x 800 pixels

16:10

SXGA+

1400 x 1050 pixels

4:3

UXGA

1600 x 1200 pixels

4:3

HD

1920 x 1080 pixels

16:9

2K

2048 x 1080 pixels

16:9

4K

4096 x 2160 pixels

16:9

Brightness

Brightness is expressed in ANSI lumens. How bright a projector needs to be is affected by factors such as room size and lighting. A brightness of 1000 lumens or less is generally fine for home cinema use in a darkened room. Projectors of 1000 to 2000 lumens may also be used effectively in lighter rooms.

Size and Weight

Most projectors designed for home cinema use are fairly compact, though it is worth comparing the size and weight of different models if the projector is to be transported regularly.

Find a Home Cinema Projector on eBay

Home cinema projectors can be located from the Sound & Vision eBay page, accessible from the eBay homepage via the left hand side tabs. Simply click on the link for DVD, Blu-ray & Home Cinema followed by Home Cinema Projectors and then choose the appropriate display technology, aspect ratio, native resolution, brightness and/or other criteria as required. Or search directly using the search bar at the top of the page, using terms such as ''home cinema projector'', ''home cinema projector 1080p'' or ''home cinema projector 16:9''.

Conclusion

Home cinema projectors can be a great way to experience cinema style viewing in the home. The main two types are LCD and DLP, each with their own advantages and disadvantages, which are especially important to note in older projectors, though less of a problem in newer models. Other factors to consider include resolution, aspect ratio, and brightness. For home cinema use an aspect ratio of 16:9 is recommended and high definition (HD) resolutions, at least 720p, provide the sharpest pictures. Brightness is not so important a consideration unless the projector is to be used in a lighter room.

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