Lux vs. Lumens

Lux vs. Lumens

Understanding the specifications of projectors is an excellent way to ensure that you know what you’re getting. Knowing what you’re paying for is critical now that the projector market is flooded with options that vary widely in quality and features.

Lux and lumens are terms that are thrown around a lot in stores and on guides online. While it’s not difficult to grasp that the terms help measure brightness, what do they really mean?

Also, is one term better than the other? How many lux or lumen should your projector have? We’ll help you with these questions and compare lux vs. lumens projectors for you in this post.

Lux is a measure of illuminance

Lux is a measurement of the amount of light that falls on a surface, which differs from the amount of light that is emitted from a light source. “X” number of photons may be emitted from a light source, but some number of those photons never make it to the surface of something you’re looking at, or they are absorbed by the surface.

Lux can vary depending on the light source, the distance the object in question is from the light source, how dark the surface of the object is, the width of the beam of light, etc. A tightly-focused flashlight beam will produce a greater lux value than an ordinary table lamp, even if the bulb is the same in both.

Lumens is a measure of luminous flux

Lumens, on the other hand, is a measurement of the light that a light source emits. Light, the instant it is emitted, travels in all directions at once, and, as we mentioned above, many of those particles of light don’t strike the surface of what we are looking at.

When you’re shopping for lighting, look for charts that make comparisons between lumens and traditional wattage. Because most of us are most familiar with incandescent wattage, it’s probably most useful to note the lumens associated with, for example, a 40-watt incandescent bulb to understand how bright, in this case, 450 lumens is.

Lumens is the most common measurement used by lighting manufacturers today

Most of the world’s light bulb makers have now adopted lumens as the standard for describing the brightness of their products. In the United States, this change is reinforced by the Federal Trade Commission, which requires all consumer packaging to carry a standardized label. A fixed set of information must be provided:

Lumens rating

Estimated energy cost

Expected lifespan

Light appearance

Energy usage in watts

Lumens is a perfectly adequate measurement for consumers, who simply know, for example, that a 100W incandescent bulb was adequate for a living room light, and so can consult a chart to know to look for a 1,700-lumen light source to get an equivalent amount of light.

Number of Lumens a Projector Needs

Choosing a projector in terms of brightness depends on how you will use it. On that note, you have three things to consider. These factors are the content, ambient light, and resolution. The cumulative assessment of these factors will give you an idea of the number of lumens your projector should have.

The content or material you plan on projecting affects the number of lumens you need. A business projector used for presentations needs fewer lumens. But if you will need it for your home theater system, the number of lumens varies.

  • Business /Portable – A minimum of 1500 lumens is enough for business and personal use.
  • Home Theater – A minimum of 2000 lumens for a projector to be used in projecting television shows or movies.
  • Gaming – A minimum of 2000 lumens is ideal if you plan to use the projector mostly for gaming.

If you only need a projector for work or school work, then 1500 lumens is good enough. But if it is for a home theater, then you should start at 2000 lumens no matter the other factors. It should increase after you considered other specifications like the lux, throw ratio, contrast, input capabilities, etc.

Besides the content, you should also keep in mind the resolution. With home theaters, the common resolutions are 1080p and 4K. Gaming platforms often use 1080p resolutions. As for most portable projectors, they usually only have 840 x 480 resolutions. These things matter along with the lumens as they will ensure the projector provides you a clear image.

Choosing the Right Projector

Knowing the inadequacies of lumen values for projectors and given the fact that most projectors only list lumens in its product specifications, how is one to apply the information described above and choose the right projector when it comes to brightness?

First off you must define the brightness level that works for your situation in terms of nits. You can do so by identifying the ambient light setting of your home theater in the table below and its corresponding nit value.

Once you have the suitable nit value you can then match it up with the image diagonal of your screen in the table below to find out the lumen value needed for your projector.

You can then head into the projector market with this data in hand and find the right projector for your home theater.

Which Is Better: Lumens Or Lux?

Lux and lumens are SI units that are used by projector manufacturers to measure their product’s brightness.

To understand lumens, you must understand luminous flux. Luminous flux is the total amount of light that a source produces in unit time.

Confusing luminous flux with radiant flux is easy if you’ve read about them before. Luminous flux is only used to measure the electromagnetic waves that are visible to human eyes. On the other hand, radiant flux measures the EM waves from all sources.

A more in-depth, more scientific explanation of lumens is that it is the measure of the number of packets of light (or “quanta”) a source of light produces. One lumen is the luminous flux that a one-candela source of light generates over a one-steradian angle.

The unit lux is very different from lumens – it is a measure of the brightness in terms of surface area. In projectors, you’ll find lux represented as lumen per square meter.

Lux takes into account how much an incident light illuminates a surface, giving a measure of how the eyes perceive the intensity of light. The spread of light, or more accurately, the area’s effect on luminous flux, is considered.

It’s not hard to see how the two units of measurement are similar. Both measure the illuminance (or, in layman’s terms, the brightness) of light, but in different contexts.

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