Projector lamp brightness vs. hours of use

[alkalifly]

Hi all, as this is my first post here, I thought I would start by saying thanks for the incredible wealth of resources that is this community.

I have two Sony VPL-PX30 projectors, one with about 650 hours on the lamp and the other with about 1100 hours. The lamps on those things are rated to 2000 hours, which I know is not exact, but I'm still hoping to get a good bit of life out of the one with 1100 hours.

At this point, if I want the brightness of the images to match, I have the one with 650 hours set to a brightness value of 50 (out of 100) and the one with 1100 hours set to a brightness value of 75. Is this simply the result of the lamp ages, and perfectly normal and expected, or could it be due to something else?

I understand that the lamps dim with age, but I was under the impression that most of that dimming comes toward the end of the lamps life, as opposed to a gradual dimming throughout the life of the lamp. It would seem that such a large difference in brightness would not be expected given the not-too-large difference in lamp age.

Thanks in advance for any input or experience you can provide!

[many2]

Projector lamp brightness is pretty much stable during its mid-life, but the beginning and the end of its life are characterized by steep drops in brightness, as you can see in the graph above.

The other factor you should consider is the age of your LCD panels. Projector LCDs get old over time, losing brightness and changing color (usually, they get yellowish). This doesn't happen with DLP technology.

By the way, if you are interested in learning more, here is the page where I took the graph from (from Christie's website) :
http://www.christiedigital.co.uk/eme...ite-lamps.aspx

[alkalifly]

Thanks, many2, for the helpful explanation and informative link

According to that graph, the age (hours of use) alone seems it's probably not enough to explain the brightness difference, I will have to consider the contribution of the LCD panels

When I was playing around with it, I was using a greyscale image; I will have to experiment with different colors and see whether or not the brightness difference is the same for each of them