When shopping for laser projectors, you may have come across terms like lux and lumens. While both seem similar and are related to brightness, they are profoundly different.
In a nutshell, lumen measures the total light output from a source, while Lux measures the light intensity per unit area.
This blog aims to demystify the difference between lux vs. lumens so you can choose the ideal metrics.
What Is Lumens
Lumens measure the total amount of light emitted by a light source from a laser or a projector lamp. Similar to water flowing out of a sprinkler.
The lumens denote the projector's total lighting capability. In other words, a higher lumen value means that the light source will be brighter.
In this manner, lumens define the brightness of the particular projector, and such a value allows the comparison between projectors intended to be used based on brightness. For instance, an average projector with a brightness of 3000 lumens will be brighter than an average 2000-lumen projector.
Understanding lumens is vital for selecting the right projector, but knowing about lux and light intensity distribution is also important to determine how bright the projected image will appear on your screen.
Understanding Lux
Lux, in contrast to lumens, measures the light intensity on a surface, specifically quantifying how concentrated light is. For instance, while lumens seem like water flowing from a sprinkler, lux is the water collected in a specific area.
Therefore, lux directly relates to the brightness of the projected image as it appears on your screen. It's about the illuminance of that projected area, the actual light intensity you perceive.
Grasping lux is essential for effective lighting design and projector placement, as it reveals how projector distance and screen size considerably influence perceived brightness.
For instance, a projector with high lumen output may produce a lower lux value—and consequently a dimmer image—if its light spreads across a large screen. In contrast, a smaller screen will concentrate the same projector's light, yielding a higher lux value and a brighter, more vivid image. Thus, while lumens indicate the strength of the projector's light, lux measures how effectively that light illuminates the screen, directly affecting your viewing experience in relation to the setup and screen size.
Lux vs. Lumens: Key Differences
|
Feature |
Lumen (lm) |
Lux (lux) |
|
Definition |
Total amount of light emitted by a source |
Light intensity on a surface |
|
Measures |
Luminous flux (lm) |
Illuminance (lm/m²) |
|
Focus |
Light Source Power (Projector Lamp/Laser) |
Brightness on Screen (Projected Image) |
|
Analogy |
Total Light from a Bulb / Water from a Hose |
Light Intensity on Skin / Paint Thickness |
|
Example Calculation |
5000 lm emitted by a bulb |
5000 lx on 1 m² = 5000 lm total on that area |
Lumens refers to the total visible light emitted by the lamp (bulb), its measurable total, regardless of direction or area in which it is emitted. Lux (lx) is the amount of light incident on a given surface; it is calculated as lumens divided by an area (square meters). This means lumens are source-centric, while lux are surface-centric.
Is 5000 Lux the Same as 5000 Lumens?
No, 5000 lux does not equal 5000 lumens. To think that way is similar to confusing the total quantity of paint in a can (lumens) with the paint thickness on a wall sprayed on (lux).
- Suppose you project 5,000 lumens onto a small screen. The light will become concentrated on that tiny screen, and the lux value will be correspondingly higher (bright image).
- While if you project the same 5,000 lumens onto a big screen, the light gets spread out over a larger area and diluted, giving a corresponding lower lux value (dim image).
Lux vs. Lumens: Relationship and Conversion
The relationship between lumens and lux is governed by the formula:
Lux = Lumens / Area (in square meters)
Thus, a projection screen with an area of 5 m² and receiving 5000 lux of uniformly distributed light would have 25,000 lumens (5000 lux times 5 m²) of total light falling on it, assuming that all light is reflected without loss.
ISO Lumens: A Reliable Measurement
ISO lumens are a standardized measure of how bright a projector is. The International Organization for Standardization (ISO 21118:2020) issued and defined them as the worldwide standard for measuring brightness.
ISO Lumens denotes the measure of projector brightness according to suitable international standards. ISO Lumens are measured in accordance with a defined, stringent, and internationally recognized canon, which ensures higher consistency and comparability across brands and regions.
Why ISO Matters for Consumers: ISO Lumens allow for a more accurate comparison of brightness in projectors and one that will be upheld across the globe, thereby saving consumers from being duped into purchasing based on misleading "peak lumens" or "light source lumens.”
At AWOL Vision, we use ISO Lumens to define brightness specifications for our UST Laser Projectors. With 3000 ISO lumens, the LTV-3500 Pro guarantees a daytime viewing experience.
Other Crucial Projector Specifications
Brightness is not everything. Instead, it is one of the several important factors.
- Resolution (1080p, 4K): The greater the resolution, 1080p or 4K, refers to a clearer picture with more graphical detail.
- Contrast Ratio (Native vs. Dynamic): This ratio explains how deep the blacks are and how dense a picture could be regarding whiteness; in other words, the greater the contrast, the more brilliant the white. Native contrast is the true level, while dynamic contrast adjusts based on the scene.
- Color Accuracy and Gamut: Color accuracy and gamut make colors appear true-to-life and vivid.
- Throw Ratio (UST Specific): Throw ratio refers to the distance between the projector and projection surface. For these types of projectors, UST actually means how big a screen may be projected at a fairly short range.
- HDR Support: HDR means higher brightness, contrast ratio, and color accuracy, which, together, produce vibrance and detail.
Making Informed Projector Choices
Knowing the differences between lux vs lumens is important for making an informed decision about a projector. Lumens refer to the amount of light emitted, while lux means the amount of illuminated light on a specific area.
There is also the ANSI lumens term regarding the measurement of lumens. ANSI stands for American National Standards Institute, which standardized a system for measuring brightness.
In addition to brightness, factors such as contrast ratio, resolution, HDR, etc., are also important to create a brighter and clearer picture.
You now know everything about projector brightness, thus making you capable of choosing wisely with confidence.
