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Genesis Media Labs - Rear Projection TV Facts

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Rear Projection Television - An Affordable Option

A great deal of consumer appeal for Rear Projection TV systems arise out of the shear simplicity that this product offers as an immediate solution to getting a bigger TV.

No mess, no fuss, if you have the space, either visit your local big screen retailer - or better still, check at your favorite online electronics superstore - to order your product and get it delivered in just a few days; unpack the product and there you have a big screen TV in your living room ready for immediate use!

Rear Projection TV Facts:

As already stated, rear projection offers a most immediate solution to getting a bigger TV. Probably, this is also one of the main drivers behind rear projection television sales.

Yet the real 'culprit' behind the popularity of rear projection TV systems does not arise out of some particular benefit associated with rear projection, but out of the fact that most big screen retailers seem to give the impression that rear projection systems are cheaper than a front projection setup.

This may be true in retail stores, but not necessary so when buying online. The reality is that for a given budget level, prices online are such that front projectors will deliver a much more cinema-like experience for the same price bracket. Therefore, do not base your decision on price alone to decide between a front projection setup and a rear projection TV box.

Clearly, there is a market for both - the primary decisive factor should be your room size. If you don't have a large viewing room, a 40" to 60" diagonal TV will probably be more than adequate rendering a rear projection TV the ideal affordable solution - as long as it fits in the available space.

Size - or rather unit depth - is becoming less of a problem with modern LCD and DLP rear projection TV units. A typical 52" diagonal widescreen DLP or LCD rear projection TV set requires no more than 15-inches in depth; this contrasts heavily with a similar size CRT rear projection model which would normally require between 22 and 24 inches in depth.

What's more, considering that a similar size Plasma TV is still out of reach of most average household budgets, today's slim-styled LCD and DLP rear projection TV sets, with their lower prices yet high performance, are becoming the affordable 'immediate' big screen TV option in the television mass-market.

However prior to committing yourself to a rear projection TV, it is important to be fully aware of a few limitations associated with rear projection systems, namely: limited screen size, limited viewing angle, glare problems, poor aspect ratio management, poor use of floor-space, etc.

We take a look at each of these limitations in further detail below:

Screen size:
Rear projection TV systems come in screen sizes ranging from typical 42" up to a maximum of just over 70". This may or may not be a limitation. It is true that you can get a 100" projection with a home theater projector for the price of a high quality digital 50" rear projection TV, yet the screen size should be dimensioned to suit your room. If your room size does not support such big projections, rear projection is probably the way to go.

Viewing angles:
Rear projection TV systems used to have a rather limited viewing angle - with the optimum viewing position being one directly in front of and eye-level with the unit. Move away to either side, and color, contrast, and brightness will degrade substantially. A narrow viewing angle will limit the number of people who can watch the set due the lowering in picture quality at the extreme viewing angles. Most modern systems support a viewing angle of circa 150 degrees - which should be adequate for normal home theater use. However, it is always best to check on this prior to your purchase as some products are worse than others.

It is common that any light source at a complementary angle to your viewing-angle will result in glare - in particular if the unit makes use of a screen-saver (a clear protective material that covers the fragile screen itself). Glare can seriously degrade the picture quality. The only real solution is to take away the offending light source; in some cases the situation can improve if one removes the screen-saver – BUT remember that an unprotected screen is fragile and expensive to replace if damaged.

Any rear projection TV is literally a large box with a relatively large footprint. It is true that modern slim-type models do exist that are no more than 15 to 18 inches in depth - depending on the screen size, yet the cheaper CRT-based rear projection TV sets will stand out by at least 24 to even 30 inches to allow for the necessary air-space between the back of the unit and the wall.

Remember to take this into your calculations when planning your home theater as these two feet or so will have to be deducted from your available viewing distance.

Rear Projection TV Speakers:
Forget all about them! Do not give any weighting to the speaker system coming with your rear projection unit. You would not be using them as you will surely want to replace these with your dedicated home theater surround receiver speaker system.

Do not even think of using the build-in speakers of your rear television set as a center channel replacement. They will just interfere with the sound coming out of your dedicated system - hence do not pay anything extra for this as you will surely be switching off your TV sound completely during a movie show.

Aspect ratios:
We have already mentioned a number of limitations associated with rear projection television, yet in comparison, these are just minor issues. The real serious limitation with a rear projection TV is aspect ratio management.

This is the trickiest of it all. Standard television comes only in 4:3 but rear projection TV systems come in both standard 4:3, and in the 16:9 widescreen format. Once you choose your format however, you have to live with it - so once again, you have to choose wisely.

The 4:3 (1.33) or 16:9 (1.78) referred to as the aspect ratio, is the ratio of the screen width with respect to the height of the image. All standard non-HDTV material is in the 4:3 format while most modern films come in one of the many widescreen formats - the most common being the 2.35, which in itself is not compatible with any of the fixed aspect ratio TV systems.

There are various ways to deal with this - including:

  • Image stretching to fill the available screen.
  • Use of black or gray bars on top and bottom of a 4:3 screen to show the movie in its correct aspect ratio as originally filmed, but then the effective film display will be smaller.
  • Pan and scan editing where only the most important portion of each frame is shown with the rest being discarded.

Image stretching and horizontal bars can be extremely irritating while in the 'pan and scan' you are giving up film information to have a full screen view. Worst of all, prolonged use of horizontal bars - especially black bars - leads to tube burn-out in CRT based systems at huge costs to you.

The incompatibility between screen formats renders the decision on aspect ratio a rather complicated issue when choosing a rear projection TV set. Surely, there is no such dilemma with a front projection setup, but if your only way forward is rear projection, then you will have to choose wisely.

Here no one can help you in your decision - it is simply a matter of preference. The best way to decide on aspect ratio is by first determining what you will be viewing most.

Making the Choice:

Surely, there is a market for both front and rear projection TVs – it is all a question of knowing what are the advantages and limitations of each with respect to your specific needs.

Andrew Ghigo – A Telecoms/Electronics engineer by profession, with specialization in digital switching and telecoms fraud management systems.

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