Five years ago, our church bought new projectors. Wow, they looked great! As a matter of fact, one still does - now.
I often get questions about how long a projector lamp lasts. Manufacturers claim 2000-5000 hours. Do the math. That's a heck of a long time, if you use your projector four hours per week - the average amount of use in most churches.
From over 25 years of selling projectors, I can tell you that if you're one of the "lucky" ones whose projector lamp lasts 2000 hours that you'll have an awful-looking picture by the time you get there. Color accuracy and brightness will have faded dramatically long ago, and contrast will be almost meaningless. At 2000 hours of use, your image will be dull and lifeless, and generally useless. If you'd like to see how bad your projector's image could look, visit any restaurant where sports are shown and where projectors are used like televisions. 12 hours of daily use, 364 days per year = less than six months to 2000 hours, and those establishments generally run them that long.
Let's get back to the story at hand. After installing our projectors, one of the lamps died about two years later. I replaced it immediately and noticed that the brightness, sharpness and accuracy no longer matched between projectors. After two years and maybe 400 hours of use, the brightness of the original lamp had faded noticeably when compared to a new lamp.
Until just a week ago, our church was using one projector with an original lamp and one projector with a "new" lamp (now three years old with about 600 hours of use). I was just about ready to replace the 5-year-old lamp (with about 1000 hours of use) when it stopped working on its own. The image was still usable, but its brightness was noticeably different from the lamp I had replaced at the two-year mark and the image quality was just missing something.
I, again, replaced the blown lamp right away and discovered that my "new" lamp (now three years old with a maximum of 600 hours) didn't look nearly as good as the brand new lamp. Imagine how bad the 5-year-old survivor would have looked by comparison.
Projector lamps don't go from 100% brightness to blowing up overnight. It's a slow fade that you won't notice until you put a new lamp in your projector - usually when the old lamp stops working. If you have 500-1000 hours of use on your projector, you should probably consider a replacement lamp to ensure optimal performance.
As much as I've enjoyed the ability to compare brightness of 2- and 3-year-old lamps to new ones, I think that I'll break down and change the other lamp so that both lamps are new. I'll save the old "new" lamp for a spare, and in a few years, it might just match the others as they fade away.