Originally Posted by ereed
With this FL talk I'm curious what mine is. I have the 16x9 120 inch white ST screen using Sony 45es projector. I use eco mode. The projector calculator shows the max FL, but I don't see where you can see diff between eco and high lamp modes?
If anyone likes to take a jab, the lens to screen is 15.5 feet.
What are the hours on the lamp?
has been recommended.
They don't have all the modes, and some of the results are with the calibrated values.
The other way to do it is manually:
1.Take the dimensions of the screen:
2.Find out the square surface:
3.Find a review with measured lumens and the effect the zoom lens on the brightness:
4.Calculate how much lens zoom is used:
5.Calculate lumens loss due to lamp use.
UHP lamps loose ~25% if their brightness in the first ~500h. After that it's a linear curve to the estimated life of the lamp, which is 50% of it's original brightness.
Different lamp modes affect the lamp's hour timer depending on the brightness. For the HW45, LOW is 40% less bright than HIGH.
If the lamp was used in different modes, take this information from the projector menu and calculate an hour value that includes all modes.
6.Calculate fL for desired mode
7.Adjust for screen gain
2.An 120" 16:9 screen has 42.71 ft²
Zoom Lens Effect. When set to the telephoto end of the 1.6x zoom range, light output is curtailed by only 17% compared with the wide angle setting-a rather modest loss for a 1.6x lens.
4. With an 120" screen positioned at 15"5' (with the HW45) the zoom factor is x1.22 (from x1.59).
x1.22 zoom factor is 62.71% from the total possible zoom.
If from total zoom to no zoom the light loss is 17%, with x1.22 the light loss is 10.6% from whatever mode used (Cinema, Game, etc).
6. Cinema Film 1 on ECO is 834 lumens. After 500h it's 625.5 lumens.
625.5 divided by 42.71 ft² is 14.64fL
The result differs from the webprojectorcalculator.
Or get a luxmeter or something similar to measure lumens and divide that by the square surface of the screen.
LE: the environment also matters, the image will be perceived brighter in a treated room (wall reflections, light control), than a room with colored walls and other light sources.