Lamp Life and Brightness
Let's start off by saying the most common Lamp life specs out there for both business and home theater projectors are:
At full power: 2000 hours
In low, or "eco" power: 3000 hours
This assumes the traditional high pressure mercury lamps used in the vast majority of projectors. There are also very expensive Xenon lamps, used in some high end projectors, and those typically have an even shorter life.
Most manufacturers rate their lamp life, not to failure, but to the point where the lamp is half as bright as it was when new.
With that in mind, remember that your projector will be noticeable dimmer as it approaches the end of its rated life. In our reviews, we try to take that into consideration.
How much loss in brightness is 50%? That's easy, consider any room. Imagine two lamps or a single 3 way light bulb. Let's say both lamps have 50 watt bulbs, or the 3 way, has a 50 watt, and a 100 watt option.
Start with both 50 watt lights on. Now turn one off. Bingo, there's your 50% drop. What that tells you, also, is that if you have some ambient light, if you can half the ambient light by the time your projector lamp is old, you can maintain the same relative brightness between image an room ambient.
A good idea is to buy a projector and screen for your room, that when new, you can enjoy watching (brightness wise), with the projector on the low power setting. On most projectors that is 20-25% less bright than full power.
If you do that, as your lamp gets dimmer, kick the projector into full power and while that won't offset the full 50% drop to end of life, it will make the loss in brightness rather minimal to the eye.
Full power vs. Eco (or low) power mode
I'm not sure who coined "eco-mode" but it has become popular with a number of manufacturers referring to their low power setting as eco-mode. Bottom line, is that low lamp, or low power, or eco-mode, pretty much are all the same thing. With most projectors, as previously noted, going from high (or full) power mode, to low, is a drop of 20 to 25% in lumens. I have seen a few projectors where the drop is barely 15% and there are also a few where the drop off is as much as 1/3, but most are in the range, of say 18 to 25%.
Be sure your projector will be bright enough
With business projectors this really isn't an issue, as most can spend a few dollars more for a projector with more than enough brightness.
In the Home Theater Projector space, however, purchase decsions are more often made primarily around picture quality, and placement flexibility, and many people will choose a less bright projector, if they feel it does a better picture. As a result, projector brightness is something people grudgingly accept. "I bought projector X because of its great picture, but really wanted a projector 25% - 35% brighter, like projector Y, but Y just doesn't have the picture quality."
In terms of lamp life ratings, the amount of drop is not necessarily an indicator of how much the lamp life will increase. In some cases, such as the JVC RS1, a drop of almost 20% gets no improvement in lamp life, according to JVC's specs. Sony's 1/3 drop off on some models, only gets the standard 2000 - 3000 hour improvement, despite the large shift in brightness.
Some Projectors get tremendous Lamp Life in eco-mode
Despite the general rule of 2000 / 3000 hours, there are some exceptions. Some Mitsubishi projectors, for example claim up to 5000 hours in eco-mode.
If operational costs are an issue for you, and you are a heavy users - say 1500 hours a year or more, then lamp life and replacement lamp costs can be a significant issue. Consider - myself, I run my own projector roughly 2000 hours a year, so for my JVC, that's an extra $350+ a year, to keep me in lamps. In reality, though, it's higher. With about 1400 hours on my lamp, I now believe I will probably replace the lamp in the next month or so, because, the overall brightness on my 128" screen, is definitely getting marginal.
Projector Lamp Costs
Except for some entry level projectors, most lamps retail for $299 to $449, with the bulk of them in the $350 - $399 range. On some high end names, for the home, such as Runco, SIM2, etc., lamp costs can run double. And, on some really high end, high power projectors, the replacement lamp (or a bundle of them, since many of those high end projectors have multiple lamps), can run into the thousands.
Index of Home Theater Projector Questions