DeskRingLight

Figure 13. Optical activity is the ability of some substances to rotate the plane of polarization of light passing through them. The rotation is detected with a polarizing filter or analyzer.

The Neewer 18-Inch arrived with a rattle inside that made me think it was shattered in transit. Thankfully, it was only the beads from a broken desiccant pack. There's not much else breakable, as the $109.99 ring is made of 204 LEDs mounted behind a white plastic soft filter. This unit seems incredibly large when set up, thanks to a substantial stainless steel tripod that keeps it upright. The tripod itself doesn't bend like the base on one of the many other, more expensive Neewer 18-inchers, but the mount does angle.

The Sun and many other light sources produce waves that are randomly polarized (see Figure 4). Such light is said to be unpolarized because it is composed of many waves with all possible directions of polarization. Polaroid materials, invented by the founder of Polaroid Corporation, Edwin Land, act as a polarizing slit for light, allowing only polarization in one direction to pass through. Polarizing filters are composed of long molecules aligned in one direction. Thinking of the molecules as many slits, analogous to those for the oscillating ropes, we can understand why only light with a specific polarization can get through. The axis of a polarizing filter is the direction along which the filter passes the electric field of an EM wave (see Figure 5).

The light itself is nice enough with 180 LEDs, but bright as it can get, you get almost zero control of color temperature—all you get is a set of white plastic diffusers (the equivalent of 5,500 K) or orange plastic diffusers. That's it.

Light rings come in several sizes, from 10 to 22 inches in diameter. Most have hundreds of small surface-mounted LEDs that can be manipulated for brightness, as well as something arguably more important: color temperature. That's what gives light the appearance of a warm orange at the low end (1,000 Kelvin) all the way up to a blinding, bright blue at 10,000 K. Most ring lights keep the range between a warm white at 3,200 K and a cool white at 6,500 K. They're (usually) easily adjusted, either digitally or with a dial, to find the most flattering color temperature.

The 3-by-5-inch mini panel that is the Lume Cube Broadcast Lighting Kit is recommended to be used in pairs to avoid shadows. If the price of $99.99 was a little lower—a dual kit is sold for $189.99—that might seem more reasonable, but this is definitely a great runner-up to the Razer Key Light Chroma.

AmazonRingLight for Phone

Figure 14. Optical stress analysis of a plastic lens placed between crossed polarizers. (credit: Infopro, Wikimedia Commons)

There is a range of optical effects used in sunglasses. Besides being Polaroid, other sunglasses have colored pigments embedded in them, while others use non-reflective or even reflective coatings. A recent development is photochromic lenses, which darken in the sunlight and become clear indoors. Photochromic lenses are embedded with organic microcrystalline molecules that change their properties when exposed to UV in sunlight, but become clear in artificial lighting with no UV.

polarization: the attribute that wave oscillations have a definite direction relative to the direction of propagation of the wave

[latex]\tan\theta_{\text{b}}=\frac{n_2}{n_1}\\[/latex] gives [latex]\tan\theta_{\text{b}}=\frac{n_2}{n_1}=\frac{1.333}{1.00}=1.333\\[/latex].

Another category of illumination might better suit some people, especially work-from-home types: LED panels (aka light panels). These are fill lights for a camera, trained on you for meetings or while streaming, and engineered for use on or around the desk where you work or perform. They come in many shapes and sizes, and some have hefty price tags. But depending on your video presence, a light panel may be the better fit.

The light from this super-slim unit is stellar. It has a wide color range of 2,900 to 7,000 K, a blinding brightness up to 2,800 lumens, and is controllable from your PC or your smartphone using Razer's apps. Like almost everything from Razer, it supports a 16.8-million-color effect that you can use to dazzle—the light can even be set to react to events that happen live in your stream. Depending on the angle(s) of your camera(s), a panel like the Key Light Chroma might best be used in pairs, which means you're doubling an already substantial financial outlay. The apps can sync up to 11 lights. The panel can be mounted in portrait or landscape mode.

To examine this further, consider the transverse waves in the ropes shown in Figure 3. The oscillations in one rope are in a vertical plane and are said to be vertically polarized. Those in the other rope are in a horizontal plane and are horizontally polarized. If a vertical slit is placed on the first rope, the waves pass through. However, a vertical slit blocks the horizontally polarized waves. For EM waves, the direction of the electric field is analogous to the disturbances on the ropes.

A fairly large angle between the direction of polarization and the filter axis is needed to reduce the intensity to 10.0% of its original value. This seems reasonable based on experimenting with polarizing films. It is interesting that, at an angle of 45º, the intensity is reduced to 50% of its original value (as you will show in this section’s Problems & Exercises). Note that 71.6º is 18.4º from reducing the intensity to zero, and that at an angle of 18.4º the intensity is reduced to 90.0% of its original value (as you will also show in Problems & Exercises), giving evidence of symmetry.

Figure 9. Long molecules are aligned perpendicular to the axis of a polarizing filter. The component of the electric field in an EM wave perpendicular to these molecules passes through the filter, while the component parallel to the molecules is absorbed.

While you are undoubtedly aware of liquid crystal displays (LCDs) found in watches, calculators, computer screens, cellphones, flat screen televisions, and other myriad places, you may not be aware that they are based on polarization. Liquid crystals are so named because their molecules can be aligned even though they are in a liquid. Liquid crystals have the property that they can rotate the polarization of light passing through them by 90º. Furthermore, this property can be turned off by the application of a voltage, as illustrated in Figure 12. It is possible to manipulate this characteristic quickly and in small well-defined regions to create the contrast patterns we see in so many LCD devices.

A ring light or LED panel may be just the beginning of your spiffed-up online persona. You may also want to learn How to Get Started in Game Streaming, and it's a perfect time to learn TikTok Tips for Beginners and Aspiring Influencers. Or maybe you just want to look nicer in a video conference. For even more ways to improve your look and even your sound, be sure to check out The Best Webcams and The Best USB Microphones.

If you search online for ring lights, you'll find hundreds of models, many from Chinese companies you've never heard of before such as Ubeesize, Aptoyu, and Mactrem. We narrowed the selection down to names like Neewer, Yesker, and Lume Cube that had some good reviews, and we even found devices from Razer, the company behind some of PCMag's favorite laptops.

Light is one type of electromagnetic (EM) wave. As noted earlier, EM waves are transverse waves consisting of varying electric and magnetic fields that oscillate perpendicular to the direction of propagation (see Figure 2). There are specific directions for the oscillations of the electric and magnetic fields. Polarization is the attribute that a wave’s oscillations have a definite direction relative to the direction of propagation of the wave. (This is not the same type of polarization as that discussed for the separation of charges.) Waves having such a direction are said to be polarized. For an EM wave, we define the direction of polarization to be the direction parallel to the electric field. Thus we can think of the electric field arrows as showing the direction of polarization, as in Figure 2.

Figure 1. These two photographs of a river show the effect of a polarizing filter in reducing glare in light reflected from the surface of water. Part (b) of this Figure was taken with a polarizing filter and part (a) was not. As a result, the reflection of clouds and sky observed in part (a) is not observed in part (b). Polarizing sunglasses are particularly useful on snow and water. (credit: Amithshs, Wikimedia Commons)

Figure 3. The transverse oscillations in one rope are in a vertical plane, and those in the other rope are in a horizontal plane. The first is said to be vertically polarized, and the other is said to be horizontally polarized. Vertical slits pass vertically polarized waves and block horizontally polarized waves.

Logitech's $60 light is no ring, and not really much of a panel because it's a square. Litra Glow is a fill light that gives you visage a little more oomph when on a video call. It seems pricey for what comes out of the box—a small 3.5-by-3.5-inch light that mounts on top of a monitor to face you, plus a 5-foot power cable (USB-C-to-USB-A). The 7-inch-long clip seems ridiculous at first, but it offsets the weight of the light to extend it upward. Optionally, take it off the clip and thread it onto a tripod.

NeewerRingLight

Figure 6 shows the effect of two polarizing filters on originally unpolarized light. The first filter polarizes the light along its axis. When the axes of the first and second filters are aligned (parallel), then all of the polarized light passed by the first filter is also passed by the second. If the second polarizing filter is rotated, only the component of the light parallel to the second filter’s axis is passed. When the axes are perpendicular, no light is passed by the second.

This newsletter may contain advertising, deals, or affiliate links. Subscribing to a newsletter indicates your consent to our Terms of Use and Privacy Policy. You may unsubscribe from the newsletters at any time.

Figure 15. Birefringent materials, such as the common mineral calcite, split unpolarized beams of light into two. The ordinary ray behaves as expected, but the extraordinary ray does not obey Snell’s law.

AmazonRingLight for Laptop

Polaroid sunglasses are familiar to most of us. They have a special ability to cut the glare of light reflected from water or glass (see Figure 1). Polaroids have this ability because of a wave characteristic of light called polarization. What is polarization? How is it produced? What are some of its uses? The answers to these questions are related to the wave character of light.

Figure 11. Polarization by scattering. Unpolarized light scattering from air molecules shakes their electrons perpendicular to the direction of the original ray. The scattered light therefore has a polarization perpendicular to the original direction and none parallel to the original direction.

Razer's 12-inch offering is a standard, low-end unit with few bells and whistles. It sells for $80 direct ($20 less on Amazon). It comes in the usual great Razer packaging, however, so you feel like you're getting a treat even if the contents are pretty standard. Inside is the light, a tripod that can adjust for desk or floor use, a flex bracket to hold a phone, and a ball-joint bracket for other cameras (such as the Razer Kiyo webcam) that have a threaded tripod mount. The button controls for the light are all found on the power cable, which plugs into a USB-A port on a PC, outlet, or power block (but a 5V 2A power block is not included).

Figure 7. A polarizing filter transmits only the component of the wave parallel to its axis, , reducing the intensity of any light not polarized parallel to its axis.

When the intensity is reduced by 90.0%, it is 10.0% or 0.100 times its original value. That is, I = 0.100I0. Using this information, the equation I = I0 cos2 θ can be used to solve for the needed angle.

ProfessionalRingLight

Unlike most of the rest, you don't get any digital read-out whatsoever to set the brightness (controlled by the on/off dial) or the color temp (a separate dial to go between 3,200K and 5,600K). If you have a color temp you like, you can set it and never touch it, but you can't with the brightness. There is a nice option, however: a USB-A charger port on the back to plug in your dying phone/camera battery as you record.

Figure 6. The effect of rotating two polarizing filters, where the first polarizes the light. (a) All of the polarized light is passed by the second polarizing filter, because its axis is parallel to the first. (b) As the second is rotated, only part of the light is passed. (c) When the second is perpendicular to the first, no light is passed. (d) In this photograph, a polarizing filter is placed above two others. Its axis is perpendicular to the filter on the right (dark area) and parallel to the filter on the left (lighter area). (credit: P.P. Urone)

I found the flex mount for the phone a little hard to work with. But once things are in place, this is an effective light to get your influencer career started. It can work behind the monitor as a decent fill light for meetings if you have the desk space. It's not perfect for either job, though the price is.

RingLight with Stand

PCMag.com is a leading authority on technology, delivering lab-based, independent reviews of the latest products and services. Our expert industry analysis and practical solutions help you make better buying decisions and get more from technology.

All we need to solve these problems are the indices of refraction. Air has n1 = 1.00, water has n2 = 1.333, and crown glass has n′2=1.520. The equation [latex]\tan\theta_{\text{b}}=\frac{n_2}{n_1}\\[/latex] can be directly applied to find θb in each case.

Figure 12. (a) Polarized light is rotated 90º by a liquid crystal and then passed by a polarizing filter that has its axis perpendicular to the original polarization direction. (b) When a voltage is applied to the liquid crystal, the polarized light is not rotated and is blocked by the filter, making the region dark in comparison with its surroundings. (c) LCDs can be made color specific, small, and fast enough to use in laptop computers and TVs. (credit: Jon Sullivan)

I don’t' know why a 14-inch light would get a model number of RL-12, but it's right there on the box. Other mysteries of the RL-12 Ring Light are why it has a very rigid extender that the paperwork describes as "flexible" (it's not—bending it was like trying to twist a lead pipe), and why, when you see the color temperature options, would anyone buy this?

In flat screen LCD televisions, there is a large light at the back of the TV. The light travels to the front screen through millions of tiny units called pixels (picture elements). One of these is shown in Figure 12 (a) and (b). Each unit has three cells, with red, blue, or green filters, each controlled independently. When the voltage across a liquid crystal is switched off, the liquid crystal passes the light through the particular filter. One can vary the picture contrast by varying the strength of the voltage applied to the liquid crystal.

Figure 10 illustrates how the component of the electric field parallel to the long molecules is absorbed. An electromagnetic wave is composed of oscillating electric and magnetic fields. The electric field is strong compared with the magnetic field and is more effective in exerting force on charges in the molecules. The most affected charged particles are the electrons in the molecules, since electron masses are small. If the electron is forced to oscillate, it can absorb energy from the EM wave. This reduces the fields in the wave and, hence, reduces its intensity. In long molecules, electrons can more easily oscillate parallel to the molecule than in the perpendicular direction. The electrons are bound to the molecule and are more restricted in their movement perpendicular to the molecule. Thus, the electrons can absorb EM waves that have a component of their electric field parallel to the molecule. The electrons are much less responsive to electric fields perpendicular to the molecule and will allow those fields to pass. Thus the axis of the polarizing filter is perpendicular to the length of the molecule.

What angle is needed between the direction of polarized light and the axis of a polarizing filter to reduce its intensity by 90.0%?

If you hold your Polaroid sunglasses in front of you and rotate them while looking at blue sky, you will see the sky get bright and dim. This is a clear indication that light scattered by air is partially polarized. Figure 11 helps illustrate how this happens. Since light is a transverse EM wave, it vibrates the electrons of air molecules perpendicular to the direction it is traveling. The electrons then radiate like small antennae. Since they are oscillating perpendicular to the direction of the light ray, they produce EM radiation that is polarized perpendicular to the direction of the ray. When viewing the light along a line perpendicular to the original ray, as in Figure 11, there can be no polarization in the scattered light parallel to the original ray, because that would require the original ray to be a longitudinal wave. Along other directions, a component of the other polarization can be projected along the line of sight, and the scattered light will only be partially polarized. Furthermore, multiple scattering can bring light to your eyes from other directions and can contain different polarizations.

By now you can probably guess that Polaroid sunglasses cut the glare in reflected light because that light is polarized. You can check this for yourself by holding Polaroid sunglasses in front of you and rotating them while looking at light reflected from water or glass. As you rotate the sunglasses, you will notice the light gets bright and dim, but not completely black. This implies the reflected light is partially polarized and cannot be completely blocked by a polarizing filter.

There are two dials on the front, one for cool light, and the other for warm, rated for a color temp range of 3,200 to 5,600 K, but you can't tell what the setting is because this unit is all analog. The hot shoe mount in the center of the light is easy to work with, but was tight even on my iPhone XS, so larger phones will be a problem. There's a bright red, Bluetooth-based smartphone camera shutter remote in the box you can use to start or stop a video, or shoot a still with your phone mounted.

We purchased five models to try in 12-, 14-, and 18-inch versions, all priced between $60 to $120. None of the light rings, not even the Razer, bowled us over, which is the trade-off for keeping the price down. But some were quite effective, and many could have the right combination of features and performance for your budget.

This utilitarian unit hits the sweet spot of price and usability for on-the-go video makers, but the sheer size makes it a lot harder to take with you. A carry bag will set you back another $57.

PCMag, PCMag.com and PC Magazine are among the federally registered trademarks of Ziff Davis and may not be used by third parties without explicit permission. The display of third-party trademarks and trade names on this site does not necessarily indicate any affiliation or the endorsement of PCMag. If you click an affiliate link and buy a product or service, we may be paid a fee by that merchant.

There's an on/off switch on the back; once the light is on, you control it with a single dial to change the brightness. Depress the dial once to adjust the color temp (3,200 to 5,600 K); depress it again to see the amount of battery left. It's all displayed on a little LED indicator screen on the rear.

Figure 4. The slender arrow represents a ray of unpolarized light. The bold arrows represent the direction of polarization of the individual waves composing the ray. Since the light is unpolarized, the arrows point in all directions.

Mobility is great, but this unit has the flimsiest of all the tripod/stands of the units I tested—it simply would not stay level. It made the whole thing seem ready to tip over at any moment, which is not what you want when you're breaking down the latest TikTok dance trend.

You've probably seen it as you scroll through Tiktok or admire someone's incredible Instagram selfie: a tell-tale ring of light in the subject's pupils. That halo in the eye is a reflection from a ring light. It's the illumination option of choice, as it lets you centrally locate a recording device, usually a smartphone, right in the middle of a light that diffuses over your face or whatever you're photographing or recording. It zaps away the shadows with uniform light.

Whether you're a social media influencer or just want to upgrade your look in web meetings, a good ring light or LED panel is a must-have companion for your camera.

Razer fans and people with plenty of cash, this is what you want. If you find it hard to justify the spend for a couple of these, there are 2-packs of full video light kits from Neewer at almost half the price, complete with phone controls. But they lack the temperature range, the Chroma effects, the desk mounts, and the overall coolness factor.

The Litra Glow is a flexible, economical, easily adjustable fill light that can only help you look better on your webcam during video meetings. Serious gaming streamers will want one of the previously mentioned panels for maximum wattage, but this is the only light around that works this well right next to a webcam.

Brewster’s angle: [latex]{\theta }_{\text{b}}={\tan}^{-1}\left(\frac{{n}_{2}}{{n}_{1}}\right)\\[/latex], where n2 is the index of refraction of the medium from which the light is reflected and n1 is the index of refraction of the medium in which the reflected light travels

Find Polaroid sunglasses and rotate one while holding the other still and look at different surfaces and objects. Explain your observations. What is the difference in angle from when you see a maximum intensity to when you see a minimum intensity? Find a reflective glass surface and do the same. At what angle does the glass need to be oriented to give minimum glare?

Brewster’s law: [latex]\tan\theta_{\text{b}}=\frac{{n}_{2}}{{n}_{1}}\\[/latex], where n1 is the medium in which the incident and reflected light travel and n2 is the index of refraction of the medium that forms the interface that reflects the light

The plusses are the very sturdy tripod/extender that goes to 61-inches high, a carry bag (which doesn't fit the tripod), and that it has the little red Bluetooth shutter control that Neewer likes to toss in. Otherwise, this $110 ($94 on Amazon) kit is better avoided for even one of the less expensive models.

Yesker's 14-inch ring light is a popular one due to the size and price ($89.99 direct, or $77.39 on Amazon). It comes with a travel bag, albeit one that doesn't hold the included tripod/stand. That stand has a telescopic rod and is identical in every way to the flimsy one that came with Lume Cube's 12-inch Ring Light, so you can kind of tell that all these companies have the same sources for parts and accessories. Yesker's 240 surface-mounted LEDs run off AC power, there's a flexible/rotatable holder for your phone, a hot shoe ball-joint unit for other cameras with a threaded tripod hole, and a small keychain Bluetooth shutter button controller with separate buttons for iOS and Android devices.

This light is light—as in flimsy-feeling—and coupled with the equally insubstantial tripod stand, it's for newbies, and not top of the line.

For a little more money than Razer's offering, the $99 Lume Cube 12-inch Ring Light comes out swinging. Not only does this one has a battery option to go cordless, but it also comes with a carry case to make that portability a reality—the bag even holds the 6.5-foot tripod/stand. There's an AC power adapter in addition to the battery and its charger. The ball-joint camera mount holds the rotatable holder for your smartphone that goes in the middle of the ring.

Figure 5. A polarizing filter has a polarization axis that acts as a slit passing through electric fields parallel to its direction. The direction of polarization of an EM wave is defined to be the direction of its electric field.

The Razer Key Light Chroma isn't a ring, but a light panel that measures 10 by 14-inches and comes with a hefty black aluminum desk mount. It's not cheap; $300 is going to be beyond what newbies can or should spend, but this isn't geared toward budding influencers. This is more for established streaming gamers looking to up their (video) game, so to speak.

I've been writing about computers, the internet, and technology professionally for over 30 years, more than half of that time with PCMag. I run several special projects including the Readers' Choice and Business Choice surveys, and yearly coverage of the Best ISPs and Best Gaming ISPs, plus Best Products of the Year and Best Brands. I work from my home, and did it long before pandemics made it cool.

Figure 10. Artist’s conception of an electron in a long molecule oscillating parallel to the molecule. The oscillation of the electron absorbs energy and reduces the intensity of the component of the EM wave that is parallel to the molecule.

Polarizing filters have a polarization axis that acts as a slit. This slit passes electromagnetic waves (often visible light) that have an electric field parallel to the axis. This is accomplished with long molecules aligned perpendicular to the axis as shown in Figure 9.

Another interesting phenomenon associated with polarized light is the ability of some crystals to split an unpolarized beam of light into two. Such crystals are said to be birefringent (see Figure 15). Each of the separated rays has a specific polarization. One behaves normally and is called the ordinary ray, whereas the other does not obey Snell’s law and is called the extraordinary ray. Birefringent crystals can be used to produce polarized beams from unpolarized light. Some birefringent materials preferentially absorb one of the polarizations. These materials are called dichroic and can produce polarization by this preferential absorption. This is fundamentally how polarizing filters and other polarizers work. The interested reader is invited to further pursue the numerous properties of materials related to polarization.

Glass and plastic become optically active when stressed; the greater the stress, the greater the effect. Optical stress analysis on complicated shapes can be performed by making plastic models of them and observing them through crossed filters, as seen in Figure 14. It is apparent that the effect depends on wavelength as well as stress. The wavelength dependence is sometimes also used for artistic purposes.

Only the component of the EM wave parallel to the axis of a filter is passed. Let us call the angle between the direction of polarization and the axis of a filter θ. If the electric field has an amplitude E, then the transmitted part of the wave has an amplitude E cos θ (see Figure 7). Since the intensity of a wave is proportional to its amplitude squared, the intensity I of the transmitted wave is related to the incident wave by I = I0 cos2 θ, where I0 is the intensity of the polarized wave before passing through the filter. (The above equation is known as Malus’s law.)

Figure 2. An EM wave, such as light, is a transverse wave. The electric and magnetic fields are perpendicular to the direction of propagation.

Figure 8. Polarization by reflection. Unpolarized light has equal amounts of vertical and horizontal polarization. After interaction with a surface, the vertical components are preferentially absorbed or refracted, leaving the reflected light more horizontally polarized. This is akin to arrows striking on their sides bouncing off, whereas arrows striking on their tips go into the surface.

For the money, you get some decent control, with color temperatures from 2,700 K to 6,500 K and a brightness of 250 lumens. You can control the whole thing analog-style with the rocker buttons on the back, but the Logitech G Hub software for Windows or Mac will also control it from your desktop if the Litra Glow is plugged directly into the computer, not a power block. With the software, you can make presets to instantly jump between the best light settings.

17. (a) 2.07 × 10−2 °C/s; (b) Yes, the polarizing filters get hot because they absorb some of the lost energy from the sunlight.

Photographs of the sky can be darkened by polarizing filters, a trick used by many photographers to make clouds brighter by contrast. Scattering from other particles, such as smoke or dust, can also polarize light. Detecting polarization in scattered EM waves can be a useful analytical tool in determining the scattering source.

Since the part of the light that is not reflected is refracted, the amount of polarization depends on the indices of refraction of the media involved. It can be shown that reflected light is completely polarized at a angle of reflection θb, given by [latex]\tan\theta_{\text{b}}=\frac{n_2}{n_1}\\[/latex], where n1 is the medium in which the incident and reflected light travel and n2 is the index of refraction of the medium that forms the interface that reflects the light. This equation is known as Brewster’s law, and θb is known as Brewster’s angle, named after the 19th-century Scottish physicist who discovered them.

This is one of the few video lights with a battery in it, so you can really take it on the road. It's supposedly ready to run for up to 16 hours. Adjustments to the brightness and the color temp (3,200 to 5,600 K) are all done with a button and dial on the side. You can read the settings, including battery life, on a small LCD on the back. You plug it in via an included USB-C-to-USB-A cable; there's also a 6-inch USB-C-to-USB-A female adapter if you want to power this from a USB-C port on your PC. If you don't care about going on the road, just leave it plugged in all the time.

Many crystals and solutions rotate the plane of polarization of light passing through them. Such substances are said to be optically active. Examples include sugar water, insulin, and collagen (see Figure 13). In addition to depending on the type of substance, the amount and direction of rotation depends on a number of factors. Among these is the concentration of the substance, the distance the light travels through it, and the wavelength of light. Optical activity is due to the asymmetric shape of molecules in the substance, such as being helical. Measurements of the rotation of polarized light passing through substances can thus be used to measure concentrations, a standard technique for sugars. It can also give information on the shapes of molecules, such as proteins, and factors that affect their shapes, such as temperature and pH.

Figure 8 illustrates what happens when unpolarized light is reflected from a surface. Vertically polarized light is preferentially refracted at the surface, so that the reflected light is left more horizontally polarized. The reasons for this phenomenon are beyond the scope of this text, but a convenient mnemonic for remembering this is to imagine the polarization direction to be like an arrow. Vertical polarization would be like an arrow perpendicular to the surface and would be more likely to stick and not be reflected. Horizontal polarization is like an arrow bouncing on its side and would be more likely to be reflected. Sunglasses with vertical axes would then block more reflected light than unpolarized light from other sources.

Light reflected at these angles could be completely blocked by a good polarizing filter held with its axis vertical. Brewster’s angle for water and air are similar to those for glass and air, so that sunglasses are equally effective for light reflected from either water or glass under similar circumstances. Light not reflected is refracted into these media. So at an incident angle equal to Brewster’s angle, the refracted light will be slightly polarized vertically. It will not be completely polarized vertically, because only a small fraction of the incident light is reflected, and so a significant amount of horizontally polarized light is refracted.

You don't get a range of color temps, only three pre-sets of 3,000 K (warm white), 4,500 K (balanced), and 6,500 K (cool white). Brightness is pre-set to 50% to start, but you can go down to 10% or up to 100% (500 lumens). The light has a threaded tripod hole, so you can mount the light ring on other tripods or holders; the included tripod goes up to 53.2-inches high.

The Lume Cube kit does come with a sticky suction cup option for placing on your desk, or better yet, the back of your monitor, to accompany your webcam as a fill light. This is helpful because the tripod extender only goes to 30 inches, which in my tests wasn't quite tall enough to peer over my main PC displays. It helps that you can orient the panel in portrait, not just landscape. The light comes with a white silicon softening diffuser around it, so the concentrated 112 LEDs—already behind a frosted lens—won't appear as harsh when reflected in your eyeballs.

Light rings typically come with a tripod of some sort. Usually, it can adjust in height to be used on a desktop or standing fully upright to capture a subject far away. A mount in the center of the ring holds a phone, typically those measuring 3.6 inches wide or smaller. Many brands seem to use the same phone bracket, and it's not going to work with a tablet or even a very fat smartphone. Most light rings offer an option for a threaded tripod mount that works with high-end digital cameras and even some webcams. Some come with special carry bags, extra-flexible arms, or Bluetooth camera-shutter activators.