To show more about how they look (and how the different lights compare), we took a bunch of selfies with different exposures (in camera) to make the lighting similar. This approach shows how the different light sizes change the face and the photo. We did not edit these photos at all.

what are the 3 typesofoptics?

The phase shift due to the film thickness in thin film interference: When light is incident straight onto a thin film (such as an oil slick on the surface of a pool of water), light rays reflecting from the top and the bottom of the film interfere (either constructively or destructively depending on the film thickness and the wavelength of the light). The following equations determine constructive or destructive interference depending on whether the phase shift produced by reflection needs to be shifted by half the wavelength (the first equation) or maintained (the second equation):

Unfortunately, the phone holder on this model has the same issues as the others — it doesn't grip phones with a large case well. We also wish the light was slightly brighter, though it's the brightest of the 10" sized lights we tested. This is a great mid-size option at a very accessible price point. If you need a brighter model, the Razer Ring Light 12" is a solid option that's cheaper than the priciest premium products we tested.

Optics study oflight

We also looked at additional features in this category. We gave products higher ratings if they included things like a remote trigger (for use with a phone), like the UBeesize 10" with Tripod, or a tripod that can turn into a selfie stick, such as the Aixpi 10" with Tripod, ShiftCam SnapGrip Creator Kit, and Rotolight Ultimate Vlogging Kit. The UBeesize 10" Tabletop tripod can technically be used this way, but it is a little impractical given the size of the light and its wired setup. Again, the ShiftCam SnapGrip Creator Kit impressed us here with the added capability of the SnapGrip portion to wirelessly charge the phone it is attached to while in use. One super basic but unique feature of the Sensyne 10" Ring Light is that the included tripod has a bubble level to ensure a superior level shot.

The lens maker’s formula: This equation allows you to calculate the focal length of a lens if all you know is the curvature of the two surfaces. Here’s the lens maker’s formula:

Snell’s law or the law of refraction: Snell‘s law shows the relationship between the incident angle and the transmitted angle (refracted angle) for a ray of light incident on a surface of a transparent material. You can see how Snell’s law works in the following formula:

The law of reflection: The law of reflection shows the relationship between the incident angle and the reflected angle for a ray of light incident on a surface. The angles are measured relative to the surface normal (a line that is perpendicular to the surface), not relative to the surface itself. Here’s the formula:

When it comes to sheer brightness, the Westcott 18" Kit edges out the Lume Cube 18". The former emits a whopping 2435 lumens, and the latter an exceptional 2267 lumens. The Neewer 18" Kit takes third at 2065 lumens, which is still extremely impressive compared to the rest of the products in our test suite. These models are wall-powered lights (though the Westcott also comes with batteries). Part of the reason for the out-of-this-world brightness on these three is their size; they both have roughly 25 times the lighting surface area as the tiny Auxiwa Clip On, which gives them quite the advantage. The Westcott, Neewer, and Lume offer continuous dimming, meaning the dimming is completely customizable. The Westcott 18" also offers a sliding tone scale, which is a rather unique feature. If you are searching for the absolute brightest, you should go with one of these larger lights. The Razer Ring Light 12" is smaller and less powerful. Still, at 789 lumens, it holds its own, especially compared to its closest competitors, the Ubeesize 10" with Tripod and Sensyne 10" Ring Light, which emit just a couple hundred lumens.

We determined value by comparing the price of a ring light to its performance (i.e., its overall score). The UBeesize 10" Table Top and Xinbaohong Clip-On are quality options if you want to save money while still getting a decently performing product. You forfeit many of the fancy features that the more expensive models offer. However, you still receive a decent light at a fraction of the price with either one.

"Common crown glasses have indices of refraction around 1.5 to 1.6, while extra dense flint glass may have an index as high as 1.75." 1.5 ...

Dummies has always stood for taking on complex concepts and making them easy to understand. Dummies helps everyone be more knowledgeable and confident in applying what they know. Whether it's to pass that big test, qualify for that big promotion or even master that cooking technique; people who rely on dummies, rely on it to learn the critical skills and relevant information necessary for success.

Diffraction is light’s response to having something mess with its path, so diffraction occurs only when something blocks part of the wavefront. Diffraction is the phenomenon where light bends around an obstacle (this bending is not due to refraction, because the material doesn’t change as refraction requires). The following equations cover the most common situations involving diffraction, including resolution.

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The location of the dark fringes produced by diffraction through a single slit: Because a slit has a width larger than the wavelength, light rays from different parts of the slit interfere with each other, creating a fringe pattern. You can relatively easily locate the points where the light destructively interferes by using the following equation:

Optics study ofchemistry

The critical angle for total internal reflection: Total internal reflection is the situation where light hits and reflects off the surface of a transparent material without transmitting through the surface. It utilizes the critical angle (the minimum angle of incidence where total internal reflection takes place.). For total internal reflection to occur, the light must start in the material with the higher index. Here’s the formula:

The location of the different diffraction orders from a diffraction grating: A diffraction grating has a very large number of slits spaced closely together, such that the light from each of these slits interferes with the light from the others. You can pretty easily identify where the light constructively interferes by using the following equation:

To measure and compare sheer brightness between these often very similar devices, we used the LT300 Light Meter by EXTECH. We were sure to measure each ring light from the same distance of 36 inches away and with no ambient light present. We even tested each light multiple times to confirm all readings. The lights in our test suite emit a large range of lumens.

Finally, almost all the lights have “color temperature” controls (besides the Auxiwa Clip-On and ShiftCam SnapGrip Creator Kit — and the Rotolight Ultimate Vlogging Kit utilizes plastic discs instead of temperatures lights, as described above). The USB lights we tested have three different controls, which allow them to provide warmer or cooler light depending on the vibe you're going for. Both the Westcott Kit and the Neewer Kit allow you to dial the white balance between 3200K and 5600K, and the Neewer Kit also includes red filters you can snap onto the light.

Location of images formed by a refracting surface: An object placed a certain distance away from a refracting surface will produce an image at a certain distance from the surface. The equation for this is

We love the versatility of the UBeesize 10" with Tripod — it comes with some great features, and they're all well-designed. It has an excellent, fully functional tripod and a carry bag for the light. There's a separate carry bag for the tripod, and it also includes an easy-to-use remote trigger for your phone. This light sets up fast (we managed it in 18 seconds), and adjusting it is a dream. It also features the same phone holder as the UBeesize 10" Tabletop, which can easily twist to whatever angle you want.

Neewer 18" — And this is it, exactly what these lights are supposed to do. You can see the catchlights in the eyes, and the face stands out from the background. There's a world of difference between this and the “no light” selfie.

The Elcometer 7062 MarSurf PS10 Surface Roughness Tester is a light and portable gauge used to measure surface roughness in accordance with International ...

Definitionof opticsin Physics

Besides imaging, fiber-optic networks are probably the largest application of optics. Fiber optics are very long, thin glass fibers that transfer information-bearing light from one place to another, but that may not be in direct sight of each other. You need to be aware of a few characteristics of the particular fiber you’re using so that you can ensure the information is accurately transmitted from one end of the fiber to the other. The following equations cover three of the basic parameters necessary for proper use of optical fibers.

The top scorer for stability is the UBeesize 10" Tripod, which proved remarkably sturdy. The Neewer and Westcott models also achieved a high score in this category (like all categories), inspiring confidence with whatever device we needed to use. The Auxiwa Clip-On, Xinbaohong Clip-On, and ShiftCam SnapGrip Creator Kit (to some extent) are also “stable” in the sense they don't require a tripod — they are as stable as your hands are.

For those looking to take their videos and photos to the next level, we've tested a ton of useful tools, from best smartphone gimbals to the top iPhone lenses and best tripods for iPhones as well as our favorite full size-tripods. With your camera phone in your pocket and the best cell phone accessories, you're sure to level up your media production.

We focused most of our testing on the amount and quality of light produced by each product. We deemed brightness the most important factor of light quality. However, a few other characteristics also come into play, like dimmability and the variety of tones each kit offers.

Browse Encyclopedia ... Focal length is the optical distance in millimeters between a camera lens and the sensor or film. It determines the height and width of ...

The Westcott 18" might be too big, depending on your lighting needs. Setup requires a tripod, so adequate floor space is necessary. Also, it lacks a remote and does not offer Bluetooth availability to control the light settings remotely. Compared to a standard ring light, this model is also a bit more expensive, but we found the high-quality construction and utility well worth the cost and great for various applications. If a compact, remote-triggered ring light is what you're after, you can enjoy the UBeesize 10" Table Top at a fraction of the price.

Reflection and refraction are two processes that change the direction light travels. Using the equations for calculating reflection and refraction, you can predict where rays encountering a surface will go — whether they reflect or refract (bounce off the surface or bend through it) — which is an important concept in the study of optics. The following equations help you determine reflection and refraction angles:

In case you haven't used many ring lights, we wanted to compare how each light size category affects a portrait. One of the big things is the “catchlights” — if someone uses a ring light, you can almost always see the characteristic circles in their eyes.

Optics study ofmatter

This review is the collective work of several veteran GearLab testers. Senior Review Editor Richard Forbes has been shooting photos with a wide range of cameras (from phone and film to pro-DSLRs) for nearly two decades and has been a working photographer for seven years. He firmly believes that photography is painting with light, so he spends way too much time thinking about how to get the right light in the right place. He loves to use ring lights on shoots and for his own selfie game. Richard is joined by Hayley Thomas, a lover of photography since she was a child, growing up with her photographer mother. She has a keen eye for composition, and her Canon Mark IV 5D is never far from her side. Ben Applebaum-Bauch has been with the GearLab team for almost six years. In that span, he has tested hundreds of home goods and electronics products, taking dozens of product photos each time. Often relying on the assistance of a ring light, he knows what to look for in these models that will bring the best user experience and lighting to the shoot.

Optical interference is just the interaction of two or more light waves. Optical interference is useful in many applications, so you need to understand some basic equations related to this optical phenomenon. The following equations allow you to calculate various quantities related to optical interference in the two most common interference arrangements.

Phase retardation in a birefringent material: A birefringent material has two indexes of refraction. When you send polarized light into a birefringent material, the two components travel through the material with different speeds. This discrepancy can result in a change in the polarization state or simply rotate the polarization state. Use this equation:

Malus’ law: This equation allows you to calculate how much polarized light passes through a linear polarizer. The equation for Malus’ law is

The index of refraction: This quantity describes the effect of atoms and molecules on the light as it travels through a transparent material. Use this basic formula for the index of refraction:

Lateral magnification: Lateral magnification is one way you can describe how big the image is compared to the original object. Here are the equations:

Femtosecond lasers and wavelength-tunable sources are the toolkits for ultrafast spectroscopy, providing high temporal resolution and a non-invasive nature to ...

No ring lights in our review came close to the light quality the Westcott model offers. Still, of the smaller lights, the UBeesize 10" with Tripod performs better than the rest, with the Sensyne 10" Ring Light with 50" Extendable Tripod following close behind. These 10" ring lights offer 240 lumens and 11 dimmer steps, and 225 lumens and 10 dimmer steps, respectively. Both come with three different warm tones for a cooler or warmer feel.

You can alter the type of light. AIHG 5X LED Magnifying Glass Desk Lamp with Clamp, USB Powered Magnifier Lamp with 3 Color Modes and 10 ...

Locating images formed by mirrors: An object placed a certain distance away from a mirror will produce an image at a certain distance from the mirror. In some cases where the mirrors are curved, you may be given the focal length of a mirror. Use these equations:

The ShiftCam SnapGrip Creator Kit is a top choice for content creators who need a reliable light on the go. This portable device turns a phone into a more traditional-looking camera by adding a shutter button, light, and detachable mini tripod to any smartphone. The tripod legs also easily collapse down into a selfie stick. This light uses MagSafe magnetic technology to quickly click in place on your phone. It even comes with an adapter sticker that turns any non-iPhone into a MagSafe magnet-compatible device. It also strikes us as high-quality and comes with a semi-rigid case to protect the light and battery.

Regarding portable models, the Rotolight Ultimate Vlogging Kit is exceptionally bright for its size, boasting up to 1000 lumens, which is multiple times brighter than lights of equivalent size. However, in terms of overall quality, this model suffers because it's not dimmable. Instead, you must manually swap the plastic temperature disks over the light face to change the light quality.

Optics study ofphysics

All of the pixel can be devoted to light capture, and the output's uniformity (a key factor in image quality) is high. In a CMOS sensor, each pixel has its own ...

There were a lot of different DSLR holders and phone holders, though some were better than others. We were impressed by the UBeesize phone holder on both models we tested: the UBeesize 10" Tripod and the UBeesize 10" Tabletop. The holder has a solid feel and grips phones well. The Lume Cube 18" has a stable tripod, but we struggled to get iPhone Plus models into the holder. The Razer Ring Light 12" and Sensyne 10" Ring Light with 50" Extendable Tripod have level tripods with a wide base. However, they are both relatively lightweight, so they can get knocked over easily if you bump into them. The Rotolight Ultimate Vlogging Kit has a stable mini tripod. But, we found that the weight of the actual light can cause the whole apparatus to tip to one side, especially if no phone is attached to anchor the other side. The Aixpi 10" LED Tabletop is so short that it has a low center of gravity, making it relatively stable. The Mactrem 6" LED strangely has two different tripods, both poorly balanced.

The Westcott 18" Bi-Color LED has you covered, from selfies to outdoor shoots. With 2435 lumens and a 3200K-5600K temperature range, you'll be set for photography, video calls, blogging, and much more. This ring light has a stepless dimmer and digital readout, allowing you to fine-tune brightness and temperature with the turn of a dial. The digital readout lets you quickly change settings based on external light conditions. The light includes two NP-F750 lithium-ion rechargeable batteries and a battery charging port. These batteries keep the light going on full power for 70 minutes, and there is also a wall-powered option for extended use. This ring light comes with a sturdy tripod and mounting accessories capable of holding a DSLR camera or smartphone. In addition, it has a USB port capable of charging phones and other electronics to avoid low battery interruptions. This light and its accessories fit nicely into a well-made storage bag with separate light, tripod, and battery compartments.

Meeting these goals demands the right people. Teamwork, adaptability, and an enthusiastic approach to problem-solving are central to the Optimax culture. But ...

Typesof optics

Aixpi 10" LED Tabletop — This one fills the face pretty well, but the right side is still lost. The photo also has a green cast, but you can start to see the ring light catchlights.

Galen Duree, Jr., PhD, is Professor of Physics and Optical Engineering at Rose-Hulman Institute of Technology in Indiana, where he is also the Director of the Center for Applied Optics Studies. Duree jointly established the Ultrashort Pulse Laser Laboratory at RHIT and continues to work with the Navy.

This light has just a few drawbacks worth noting. First, it is not especially bright. It does the job for selfies or anything within close range but much more than an arm's length away, and its effectiveness fades fast. Second, it's heavy, which you might notice if you plan on taking a bunch of selfies with the included stick. When attached to the stick, the weight of the light combined with a phone sometimes forces the pivoting ball joint to slump over at an angle. However, for convenience and quality in a tiny package, this light is our go-to when on the go. If you can't swing the cost, check out our favorite portable budget model, the Xinbaohong Clip-On. It's lightweight, affordable, and fits in your jacket pocket, so you can take a selfie whenever the moment strikes.

Ring lights are an essential tool for anyone who films or photographs faces. They provide a kind and diffused light that removes shadows and helps subjects stand out from their backgrounds. Even if you're just doing a ton of Zoom calls, ring lights will help you look your best. Our expert testers subjected each product to a series of rigorous tests designed to reveal any strengths or weaknesses and then sorted the results into four weighted categories.

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Auxiwa Clip-On — This light isn't bright enough to do much; you can see how it doesn't fill in the right side of the face.

Imaging is a key function of optics. Specific optics equations can help you determine the basic characteristics of an image and predict where it will form. Use the following optics equations for your imaging needs:

Optical polarization is the orientation of the planes of oscillation of the electric field vectors for many light waves. Optical polarization is often a major consideration in the construction of many optical systems, so equations for working with polarization come in handy. The following equations highlight some important polarization concepts. The equations listed here allow you to calculate how to make polarized light by reflection and to determine how much light passes through multiple polarizers:

Seeking to improve the light quality of your photos or videos? We researched over 60 top contenders and purchased the 14 best ring lights for some quality hands-on time. We put each one through the wringer to ensure a well-rounded testing process. We shot a ton of selfies and portraits, timed the setup and breakdown of each model, assessed stability and durability, and came away feeling confident that we'd tested these lights to the best of our abilities. Read on to learn more about our favorites and our testing methods. Your home photos will level up in no time!

Mactrem 6" — This one fills the face better; you can't see the side lighting as dramatically, but you still can't see the characteristic eye “catchlights.”

As with many things, if a product is unnecessarily complicated, you may not use it. Within this metric, there was a wide range of well-designed (and not so well-designed) products, and to sort out which products made it the easiest for us, we set them up and broke them down repeatedly.

To test ring lights, we took hundreds of photos with each of these devices and conducted controlled photo experiments to measure relative brightness. We played with all the different features, timed setups and breakdowns to assess ease of use, and monitored stability by attaching our phones and cameras to each product. We determined the durability by physically comparing each model throughout our testing and digging through online user reviews to find any frequent issues to watch for while testing.

Polarizing angle or Brewster’s angle: This angle is the angle of incidence where the reflected light is linearly polarized. Here’s the equation:

Our timed setup test revealed this most clearly, as the large Neewer and Westcott lights took the longest to set up (at roughly one minute and 15 seconds each), while the Xinbaohong Clip-On and Auxiwa Clip-On took only five seconds to clip onto a phone (though the Xinbaohong also blocks the rear-facing camera on an iPhone, so it's primarily useful for selfies). In the middle of the pack, some lights were unnecessarily fiddly: in particular, the Aixpi 10" with Tripod took 50 seconds to set up just because the parts didn't fit together well.

Resolution: Resolution is the minimum angular separation between two objects such that you can tell that there are two distinct objects. Here’s the equation for determining resolution:

In film photography, the numbers on the ISO chart refer to the quantity, size, and density of the light-sensitive layers of silver halide crystals that cover ...

The thin lens equation: An object placed a certain distance away from a lens will produce an image at a certain distance from the lens, and the thin lens equation relates the image location to the object distance and focal length. The following is the thin lens equation:

Like most bargain buys, there are some downsides to consider. For instance, we wish the phone mount was more compatible with larger phone cases (e.g., Otterbox). Also, this smaller ring light costs less than others in our lineup and, as a result, lacks the brightness that larger, more expensive models do. That said, neither issue is a dealbreaker compared to how much we like this light. The UBeesize 10" Table Top is a small, simple, and portable option, all at an unbeatable price. If you require a model compatible with larger phones, the Westcott 18" Bi-Color LED is a more viable option. It features a remarkably bright light and works with large phones and cameras alike.

The ring light you choose must stand up with a camera/phone attached. We set up each model, attached the largest camera or phone possible, and then jostled it vigorously to see whether it could stay up. We also assessed whether each could support a phone or DSLR and whether we felt confident that our electronics were actually going to stay where we put them.

To understand durability, we spent time setting up and breaking down each light repeatedly to identify any weak spots they might have. We supplemented our assessments by reading user reviews to see if there were any common problems. We were sure to put them through all the paces that a busy videographer or photographer might.

On the other hand, the Westcott 18" Ring Light is one of the most expensive ring lights we tested, so we would expect it to perform extremely well across all of our metrics, and it does. It delivers value with excellent light quality and sheer brightness. It is easy to use, stable, and durable, making it a versatile and long-lasting product. That said, this option is only worth the money if you are looking for a more advanced model. If you want something of high caliber but don't need or want to pay for extra features, the Neewer 18" Kit is another solid value pick.

Optics study ofrefraction

The ShiftCam SnapGrip Creator Kit is simple once you have the hang of it, but there are three layers between the MagSafe adapter sticker, the light itself, and the tripod/selfie stick, so it takes a minute to figure out how it all needs to go. We like the similar designs of the Sensyne 10" Ring Light with 50" Extendable Tripod and the Razer Ring Light 12". They have legs that deploy in three stages for easy adjustment. The Sensyne, however, has a max height of 50 inches, so it's not quite tall enough for most adults to be used if you are standing up.

Intermodal dispersion in a fiber: This characteristic measures the difference in time that different fiber modes take to reach the end of the fiber. The larger this time difference, the shorter the fiber has to be so that the information on this light doesn’t turn into junk. Here’s the equation:

The numerical aperture for a fiber: The numerical aperture is a measure of the light-gathering power of the fiber. It has a maximum value of 1 (all the light remains trapped inside the fiber) and a minimum value of 0 (only light incident at an angle of 0 degrees on the end of the fiber remains trapped in the fiber). Use this equation:

The Xinbaohong Clip-On is a lightweight and compact clip-on ring light for smartphones. It offers multiple temperature settings, continuous dimmer capability, and the most basic setup imaginable — all at a very affordable price. It clips directly to the phone, like a chip clip. A single power button turns the light on, and successive presses cycle through the temperature modes. Super easy. It can easily fit into a backpack, purse, or jacket pocket. This is a great option for budget-conscious social media posters and selfie-takers alike.

In addition, it would be disingenuous to ignore the obvious issue with a “brightness only” approach. This test has a huge range of sizes, from the enormous 18" Neewer model to the tiny Auxiwa Clip-On. Obviously, the largest lights should be the brightest, so we also measured the ring lights' exact sizes (which were roughly as advertised) and compared these values to brightness values.

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Almost all of the lights have varying brightness levels, from the stepless dimming of the Westcott 18" Kit and Neewer 18" Kit to the 9-11 brightness settings of the USB lights to the four and three levels, respectively, of the ShiftCam SnapGrip Creator Kit and Auxiwa Clip-On. However, we found ourselves almost always using the lights to their full capacity, so the dim settings didn't matter much.

The ShiftCam SnapGrip Creator Kit and Rotolight Ultimate Vlogging Kit are some of the most sturdy portable models. This is partly due to their smaller size — fewer hinges and joints to break on tripods, for example. However, they are also both well-constructed. The ShiftCam is rubber-coated and comes with a zippered protective semi-rigid case for travel, while the Rotolight has a durable metal T-bar mount. The UBeesize and Westcott lights are the heartiest of the bigs, and we are confident the UBeesize 10" Tabletop, UBeesize 10" Tripod, Razer Ring Light 12", Westcott 18" Kit, and Neewer 18" Kit will all last a long time. On the other end of the spectrum, the Xinbaohong Clip-On, Auxiwa Clip On, Mactrem 6" LED, and Aixpi 10" with Tripod are all underwhelming and strike us as liable to break if the light were to fall on the floor.

Empirical Formula (Hill Notation): C16H14F3N3O2S. CAS No.: 103577-45-3. Molecular Weight: 369.36. Compare, Product No. Description, SDS, Pricing ...

The location of the bright and dark fringes in Young’s two-slit interference arrangement: The following equations allow you to calculate the location of the bright fringes (where constructive interference occurs) and dark fringes (where destructive interference occurs):

The maximum acceptance angle for a fiber: This angle is the largest angle of incidence at which light can enter the end of the fiber and be totally internally reflected inside the fiber. Angles of incidence larger than this angle will transmit through the sides of the fiber and not make it to the other end. The equation for this angle is

While the price is right, this ring light has some downsides. When using it in a portrait orientation, the clip mount blocks the rear-facing camera of many phones, which is an issue when taking a non-selfie photo. To mitigate this problem, you either have to slide it to the corner or a different side of the phone. Another consideration is the light itself is not particularly bright, so if you photograph anything more than an arm's length away, this light won't make a noticeable difference. Also, for everything we love about this mini light, it feels lower quality than other premium portable options. Still, for its simplicity and ease of use at a steal of a price, the Xinbaohong is a nice portable light for selfies. If you have a little wiggle room in your budget, check out the well-designed UBeesize 10" with Tripod, which includes a solid tripod and is quite bright.