Originally Posted by djams
I made an effort at converting these as well. My first stop was WolframAlpha, which states that "lux and nits are incomptible".http://www.wolframalpha.com/input/?i...rt+lux+to+nits
I then found 2 more luminance conversion sites where it is not possible to convert between the two units.http://www.unitconversion.org/unit_c...inance-ex.htmlhttp://www.sooeet.com/light/lux.php
It seems the problem is that lux is a measurement of illuminance, while nits is luminance. I found this
simple explanation if the difference, which explains why, for a projector setup, lux could be used to measure the bulbs and nits would be used to measure on the screen. However, it confuses me why we use nits or fL to measure a display that emits a light source. Seems like it should be lux, technically. *shrug*
At any rate, I think the % changes measured using either unit are valid.
Yes, I ran into the same seemingly contradictory information. While illuminace is one thing and luminance is another. . . one is basically reflected light and the other source light. However, electronically, the sensor used to measure them is the same type of photo diode. The only difference is in what the meter is set up to DO with the output of the photo diode sensor.
So, yes, I also agree you it seems the measurement units are related, they
are not directly converted. "Gain" is not something that is relevant to an emissive LCD panel. . only a reflective projection screen. The units are actually irrelevant in this case and the rise measured in lux would still be the same if measured with a meter that uses fl, lumens, etc.
A lux meter is usually used to measure the amount of light in rooms for technical purposes such as office lighting, minimum levels in various room locations etc. So , technically, it IS reading source light . . . but from a distance and how much in a given area. So I guess I could put the meter 6 feet way from the screen in a completely dark room and see if I get a similar light output rise. But there is less chance of ambient light "leaking" around the edge of the photo diode sensor by placing it right on the LCD screen. You only need
a meter that reads in fl or candelas per square meter if you are actually interested in the actual amount
of emitted light. In the case of light output rise all we need is a a relative starting and ending point. You could even take a simple digital volt meter and connect a photo diode to it placed on the screen of the LCD panel and read the starting and ending values in volts. The percentages would be the same. All a light meter does it determine what units the voltage output of the photo diode is going to display.