Choosing a digital projector can seem like a daunting task. Ideally, your camera club should trial a short-list of projectors in your club room in front of some discerning members. Unfortunately it is difficult to find a retailer who keeps many projectors in stock, let alone offers them for demonstration purposes, so it is often necessary to buy a projector based only on the specifications. To help you choose, here are a few things to consider.

Technology - DLP vs LCD

When it comes to digital projectors, there are two mainstream competing technologies: Digital Light Processing (DLP) and Liquid Crystal Display (LCD). Each has its pros and cons.

DLP has the benefit of excellent contrast, which produces really good blacks if the room is dark enough. On the downside, some people can see rainbow colours when their eyes scan the projected image.

LCD colours are arguably more naturalistic and accurate and historically the projectors have been cheaper, but LCD can produce a visible grid on the screen.

Both technologies can produce stunning images and developments are continually improving the results that they can achieve so there is no clear winner and both have their advocates. Over time other emerging technologies such as LCOS may join the mainstream bringing their own price/performance benefits.

Resolution

Minimum resolution should be XGA (1024x768 pixels). Just as with digital cameras there will be a gradual increase in resolution over time but although XGA amounts to less than one megapixel, that is sufficient to produce images of high quality and detail, because of the brightness, contrast and viewing distances involved. Higher resolution than XGA is an advantage if the budget is sufficient. SXGA at 1280x1024 puts 60% more pixels on the screen than XGA. Of course, you need a laptop or computer capable of displaying at the chosen resolution, and older equipment may not handle SXGA.

Contrast Ratio

The minimum contrast ratio should be 600:1, but 1000:1 or greater is better. Low contrast will result in disappointing blacks, irrespective of the quality of the room blackout.

Screen Format

Projectors are mostly either 4:3 or widescreen 16:9 although SXGA projectors are 5:4. Compact digital cameras are usually 4:3 but digital SLRs follow the traditional 35mm film format of 3:2. An exact match between all images and the projector is therefore impossible but the main recommendation would be to avoid widescreen 16:9 projectors because images in portrait format would be severely cramped and disadvantaged in terms of on-screen size.

Brightness

This depends upon the size of the room, blackout conditions, screen type and personal preferences but a projector in the range 1000 to 2000 lumens is likely to be a safe choice. LCD projectors tend to be brighter than DLP.

Zoom Lens

Most projectors have a zoom lens to make fine adjustments to the image size without moving the projector. These can be quite limited in range and powered or unpowered. Many projectors are designed for office use and have a short-throw wide-angle lens. This will result in the projector being located more closely to the screen than has typically been the case with traditional 35mm projectors. Digital projectors are available with interchangeable lenses but these are normally prohibitively expensive.

Other Features

It may be advantageous to have features such as back-projection (e.g. for exhibitions). A quiet fan is also a benefit. Although some form of keystone correction is usually built-in, it is preferable to position the projector correctly rather than use this feature as it has a detrimental impact on image quality. Portability is also likely to be important unless the projector can be securely stored nearby to the clubroom.

Screen

Highly reflective or directional (eg beaded) screens may not be suitable for a digital projector and a larger room. In addition to uneven illumination, a beaded screen can produce moire patterns with some digital projectors. A grey or non-beaded white screen should produce acceptable results, but this could be a good opportunity to consider replacing an old screen with a modern one.

Colour Management

It is essential to have the projector/computer combination professionally colour-profiled to ensure that they deliver accurate colours. In practice, this requires you to use the same computer and projector every time as the profile actually resides on the computer.

Extra Equipment

Other equipment to consider during a procurement exercise could include: a computer or laptop (ideally with matching screen format and resolution), competition software, other software (e.g. Photoshop & anti-virus software), colour profiling, protective cases, a projector stand and a screen. You may also find that the equipment generates a resurgence of interest in audio-visuals, in which case you may need to purchase suitable powered speakers. As the life of the projector bulb is measured in thousands of hours, you may consider it unnecessary to purchase an extraordinarily expensive spare bulb, as the life of the projector is likely to exceed the life of the bulb and gas-discharge lamps do not usually fail prematurely.

Planning Ahead

Whichever projector and computer you decide upon, bear in mind that they will be obsolete within five years. In addition, the equipment will require periodic maintenance and software upgrades, so it is strongly recommended that funding is put aside annually for maintenance and eventual replacement.

Further information on choosing a projector can be found at Projector Point.

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