To overcome the aforementioned challenges with RGB and white LED backlights an 'advanced remote phosphor' [20] LED technology has been developed by NDF Special Light Products, specifically for high-end and long-life LCD applications such as cockpit displays,[21] air traffic control displays, and medical displays. This technology uses blue pump LEDs in combination with a sheet on which phosphorous luminescent materials are printed for colour conversion. The principle is similar to quantum dots, but the phosphors applied are much more robust than the quantum dot nano-particles for applications that require long lifetime in more demanding operational conditions. Because the phosphor sheet is placed at a distance (remote) of the LED it experiences much less temperature stress than phosphors in white LEDs. As a result, the white point is less dependent on individual LEDs, and degrading of individual LEDs over lifetime, leading to a more homogenous backlight with improved colour consistency and lower lumen depreciation.

Nov 21, 2024 — Their ability to observe living organisms and cells makes them essential for many types of biological studies, as well as general lab work.

Light meters are great and can save you a ton of time instead of the trial and error that’s inherent to shooting without one. They are not artists though, and can only tell you what the proper settings should be for a “correctly” exposed photograph. That doesn’t mean that that’s what you’re after. Maybe you’re trying to create something really dramatic and dark, extra contrasty, or light and airy. That’s why it’s also important that you make the final judgment call in how your want your photo exposed. The light meter will get you there right away most of the time, but other times it’ll just get you in the ballpark and you’ll want to adjust so that the result looks like what you wanted.

Wondering about which lens focal lengths are best for portrait or landscape photography? This chart should help out in your lens choice.

For a non-ELP backlight to produce even lighting, which is critical for displays, the light is first passed through a lightguide (Light guide plate, LGP) - a specially designed layer of plastic that diffuses the light through a series of unevenly spaced bumps. The density of bumps increases further away from the light source according to a diffusion equation. The diffused light then travels to either side of the diffuser; the front faces the actual LCD panel, the back has a reflector to guide otherwise wasted light back toward the LCD panel. The reflector is sometimes made of aluminum foil or a simple white-pigmented surface.

This mode is probably what you’ll end up using most often if you’re shooting with flash. Some light meters have an integrated radio that can trigger the flash remotely. Sekonic L-308S-U is a more bare bones meter, so it doesn’t have a radio. What you’ll do instead is press the button to take a reading and then the meter will be in standby and wait for a flash to happen. You can just press to take a reading and then press the test button on your flash remote trigger.

So maybe it’s all starting to make sense for you, but you may be wondering about how it works with natural light vs constant light vs flash. That’s where metering modes come in!

When metering in flash mode, you’ll almost always want to set your ISO to the lowest possible value for your camera (100 for most cameras) and your shutter speed to your camera’s sync speed (1/250s for my Nikon camera), so it becomes a no-brainer really.

Advanced illumination

Very good question! There are different schools of thought when it comes to that. Some say you should always point the meter at the camera, some say you should always point it at the light.

20221222 — The best place to start would be a full spectrum 6500K 95+ CRI LED light but depending on the model it might still have a large blue color bias.

To take a meter reading, you place the meter in front of your subject and take a reading. For portraits, it’s common practice to place the meter right under the model’s chin, because it can otherwise be a little annoying to the model to place the meter right in front of their eyes.

Colored LED backlighting is most commonly used in small, inexpensive LCD panels. White LED backlighting is becoming dominant. ELP backlighting is often used for larger displays or when even backlighting is important; it can also be either colored or white. An ELP must be driven by relatively high[specify] voltage AC power, which is provided by an inverter circuit. CCFL backlights are used on larger displays such as computer monitors, and are typically white in color; these also require the use of an inverter and diffuser. Incandescent backlighting was used by early LCD panels to achieve high brightness,[8][9] but the limited life and excess heat produced by incandescent bulbs were severe limitations. The heat generated by incandescent bulbs typically requires the bulbs to be mounted away from the display to prevent damage.

Some meters, the Sekonic L-308S-U included, will only allow to use the ambient mode in shutter priority mode. In other words, you can only set the shutter speed and the ISO. Most of the time though shutter priority mode is what you’ll be after anyway, so it shouldn’t be a problem.

Most LED backlights for LCDs are edge-lit, i.e. several LEDs are placed at the edges of a lightguide (Light guide plate, LGP), which distributes the light behind the LC panel. Advantages of this technique are the very thin flat-panel construction and low cost. A more expensive version is called full-array or direct LED and consists of many LEDs placed behind the LC panel (an array of LEDs), such that large panels can be evenly illuminated. Full-array local dimming is often abbreviated as "FALD". This arrangement allows for local dimming to obtain darker black pixels depending on the image displayed.

The light meter has a white dome called a lumisphere which reads 180 degrees of light in the scene and averages it to arrive at a mid-gray. This is called incident metering, meaning the reading is made by actually receiving the direct light that’ll be used to expose your photograph. That’s different than reflective metering, which reads that light that’s reflected back and is the type of metering that cameras do.

An ELP gives off uniform light over its entire surface, but other backlights frequently employ a diffuser to provide even lighting from an uneven source.

For several years (until about 2010), the preferred backlight for matrix-addressed large LCD panels such as in monitors and TVs was based on a cold-cathode fluorescent lamp (CCFL) by using two CCFLs at opposite edges of the LCD or by an array of CCFLs behind the LCD (see picture of an array with 18 CCFLs for a 40-inch LCD TV). Due to the disadvantages in comparison with LED illumination (higher voltage and power needed, thicker panel design, no high-speed switching, faster aging), LED backlighting is becoming more popular.[citation needed]

Most light meters also have the ability to take a reflective reading, but for the rest of this post we’ll focus on incident metering, which the way light meters for photography are used most of the time anyway. Using reflective metering can be useful if, for example, your subject is too far and it’s not really possible to go get a meter right where your subject is at. On the Sekonic L-308S-U meter, you can push the lumisphere to the side to use the reflective metering.

There are several challenges with LED backlights. Uniformity is hard to achieve, especially as the LEDs age, with each LED aging at a different rate. The use of three separate light sources for red, green, and blue means that the white point of the display can move as the LEDs age at different rates; white LEDs are affected by this phenomenon, with changes of several hundred kelvins of color temperature being recorded. White LEDs suffer from blue shifts at higher temperatures varying from 3141K to 3222K for 10 °C to 80 °C respectively.[19] Power efficiency may be a challenge; first generation implementations could potentially use more power than their CCFL counterparts, though it is possible for an LED display to be more power efficient.[citation needed] In 2010, current generation LED displays can have significant power consumption advantages. For example, the non-LED version of the 24" Benq G2420HDB consumer display has a 49W consumption compared to the 24W of the LED version of the same display (G2420HDBL).

A review of some early backlighting schemes for LCDs is given in a report Engineering and Technology History by Peter J. Wild.[2]

I’ll use the Sekonic L-308S-U light meter as an example, but the principles will apply to just about any handheld light meter. If you want to get a light meter though and not sure what to buy, that Sekonik model would be a great choice because it’s cheap, but has all the features you’ll likely need.

RGB LEDs can deliver an enormous color gamut to screens.[12] When using three separate LEDs (additive color) the backlight can produce a color spectrum that closely matches the color filters in the LCD pixels themselves. In this way, the filter passband can be narrowed so that each color component lets only a very narrow band of spectrum through the LCD. This improves the efficiency of the display since less light is blocked when white is displayed. The actual red, green, and blue points can be moved farther out so that the display is capable of reproducing more vivid colors.

A backlight is a form of illumination used in liquid-crystal displays (LCDs) that provides illumination from the back or side of a display panel. LCDs do not produce light by themselves, so they need illumination (ambient light or a special light source) to produce a visible image. Backlights are often used in smartphones, computer monitors, and LCD televisions. They are used in small displays to increase readability in low light conditions such as in wristwatches.[1] Typical sources of light for backlights include light-emitting diodes (LEDs) and cold cathode fluorescent lamps (CCFLs).

Many LCD models, from cheap TN-displays to color proofing S-IPS or S-PVA panels, have wide gamut CCFLs representing more than 95% of the NTSC color specification.

The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure to gain the light into the desired viewer directions and reflective polarizing films that recycle the polarized light that was formerly absorbed by the first polarizer of the LCD (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman),[29] generally achieved using so called DBEF films manufactured and supplied by 3M.[30] These polarizers consist of a large stack of uniaxial oriented birefringent films that reflect the former absorbed polarization mode of the light.[31] Such reflective polarizers using uniaxial oriented polymerized liquid crystals (birefringent polymers or birefringent glue) are invented in 1989 by Philips researchers Dirk Broer, Adrianus de Vaan and Joerg Brambring.[32] The combination of such reflective polarizers, and LED dynamic backlight control[23] make today's LCD televisions far more efficient than the CRT-based sets, leading to a worldwide energy saving of 600 TWh (2017), equal to 10% of the electricity consumption of all households worldwide or equal to 2 times the energy production of all solar cells in the world.[33][34]

The use of LED backlights in notebook computers has been growing. Sony has used LED backlights in some of its higher-end slim VAIO notebooks since 2005, and Fujitsu introduced notebooks with LED backlights in 2006. In 2007, Asus, Dell, and Apple introduced LED backlights into some of their notebook models. As of 2008[update], Lenovo has announced LED-backlit notebooks. In October 2008, Apple announced that it would be using LED backlights for all of its notebooks and new 24-inch Apple Cinema Display, and one year later it introduced a new LED iMac, meaning all of Apple's new computer screens became LED-backlit displays. Almost every laptop with a 16:9 display introduced since September 2009 uses LED-backlit panels. This is also the case for most LCD television sets, which are marketed in some countries under the misleading name LED TV, although the image is still generated by an LCD panel.

The meter in your camera is really useful, but doesn’t cancel out the usefulness of a handheld light meter. The meter in your camera is a reflective meter and tries to make the overall scene average to a mid-gray. The meter reading will therefore be off when you’re trying to take a photograph of something that’s really light or really dark.

By default most meters are set to show values at either 1/5 stop or full stop increments, but most cameras and flashes use 1/3 stop increments instead. For accurate values, it’s therefore pretty important that you set your light meter to use 1/3 stop increments. With the Sekonic L-308S-U, hold the power button at the same time as the mode button, the display will then show the current increment selection. Press the mode button to set it to 0.3. Now just hold the power button to power off the meter and save the new setting.

Plus, the light meter in your camera can’t meter the light output coming from your flashes. So with flash photography the meter in the camera becomes pretty useless really.

Using PWM (pulse-width modulation, a technology where the intensity of the LEDs are kept constant, but the brightness adjustment is achieved by varying a time interval of flashing these constant light intensity light sources[26]), the backlight is dimmed to the brightest color that appears on the screen while simultaneously boosting the LCD contrast to the maximum achievable levels

2022117 — This article offers a basic introduction to what light is and how it is measured along with a guide on how to use a Light Meter (Luxmeter).

You most certainly can, and many photographers never use a light meter. You’ll just have to do more trial and error to arrive at the proper exposure. With time though, you’ll tend to become pretty familiar with your equipment and able to take pretty good guesses without as much trial and error.

If you’re shooting with flash, but don’t have an easy way to trigger your flashe(s) remotely from where you are when you’re metering, you can use a PC sync cable with one end connected to the light meter and the other end connected in the flash. With that setup, pressing to take a reading will trigger the flash. On the Sekonic L-308S-U, the cordless flash mode is represented by a lightning bolt icon ⚡ and a little “c” next to it.

LED backlight are often dynamically controlled using the video information[22] (dynamic backlight control or dynamic "local dimming" LED backlight, also marketed as HDR, high dynamic range television, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan[23][24][25]).

Your photos are turning out a bit soft or you miss focus a bit too often? Check out these 17 tips to help improve the sharpness of you images.

So, for example, if your camera is set for an aperture of f/11 but your meter reads at f/8, you’ll want to increase the power output on your flash by a stop so that it then meters at f/11.

If you’re shooting with flash, a good rule of thumb is to set your camera at whichever aperture you want to shoot, and then take meter readings and adjust your flash’s output power until your meter reading reflects what your camera is set at. Having your camera set at a specific aperture value and tweaking the flash(es) instead is a good idea because if you change your camera’s aperture setting all your flashes will be affected at once, versus being able to tweak each flash on its own.

A method to further improve the color gamut of LED-backlit LCD panels is based on blue LEDs (such as gallium nitride (GaN) LEDs) that illuminate a layer of nanocrystal phosphors, called quantum dots (QDs).[13] The quantum dots convert the blue wavelengths to the desired longer wavelengths as narrow-bandwidth green and red colors for optimal illumination of the LCD from behind. The manufacturer, Nanosys, claims that the color output of the dots can be tuned precisely by controlling the size of the nanocrystals. Other companies pursuing this method are Nanoco Group PLC (UK), QD Vision, 3M a licensee of Nanosys and Avantama of Switzerland.[14][15] Sony has adapted quantum dot technology from the US company QD Vision[16] to introduce LCD TVs with an improved edge-lit LED backlight marketed under the term Triluminos in 2013. With a blue LED and optimized nanocrystals for green and red colors in front of it, the resulting combined white light allows for an equivalent or better color gamut than that emitted by a more expensive set of three RGB LEDs. At the Consumer Electronics Show 2015, a number of companies showed QD-enhanced LED-backlighting of LCD TVs, including Samsung Electronics, LG Electronics, and the Chinese TCL Corporation.[17][18]

J Ye · 2024 · 16 — Conventionally, linear polarization is obtained by passing unpolarized light through a linear polarizer, which is typically constructed from ...

For example, if you know you want to shoot at ISO 100 and at a shutter speed of 1/160s, you’ll input those in the meter and then take a meter reading to get the aperture you should be shooting at for proper exposure.

Jun 10, 2022 — Light meters are used to measure the amount of light in a given area, including ambient light, direct light, reflected light and incident ...

I actually like Mark Wallace’s breakdown in this video and agrees with his opinion that it depends on what you’re trying to prioritize. If you point the meter at the camera, you’ll get a good overall reading for an exposure that’s correct throughout, and if you point it at the light you’ll get a right exposure that’s more targeted at where that light falls. If your goal is a higher contrast image, pointing at the light makes sense, but if you want things more even stevens, then pointing at the camera is the best bet.

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202466 — Polarization of light refers to the phenomenon in which waves of light or electromagnetic radiation are restricted to vibrate in a single ...

The evolution of energy standards and the increasing public expectations regarding power consumption have made it necessary for backlight systems to manage their power. As for other consumer electronics products (e.g., fridges or light bulbs), energy consumption categories are enforced for television sets.[35] Standards for power ratings for TV sets have been introduced, e.g., in the USA, EU, and Australia[36] as well as in China.[37] Moreover, a 2008 study[38] showed that among European countries, power consumption is one of the most important criteria for consumers when they choose a television, as important as the screen size.[39]

LED backlighting in color screens comes in two varieties: white LED backlights and RGB LED backlights.[10] White LEDs are used most often in notebook computers and desktop screens, and make up virtually all mobile LCD screens. A white LED is typically a blue LED with broad spectrum yellow phosphor to result in the emission of white light. However, because the spectral curve peaks at yellow, it is a poor match to the transmission peaks of the red and green color filters of the LCD. This causes the red and green primaries to shift toward yellow, reducing the color gamut of the display.[11] RGB LEDs consist of a red, a blue, and a green LED and can be controlled to produce different color temperatures of white. RGB LEDs for backlighting are found in high end color proofing displays such as the HP DreamColor LP2480zx monitor or selected HP EliteBook notebooks, as well as more recent consumer-grade displays such as Dell's Studio series laptops which have an optional RGB LED display.

So you’re wondering about light meters for your photography? In this post I’ll try to distill down the essentials to get you up and running with using a light meter. I’ll finish up by answering a few common quesions.

The basic idea of a light meter is to measure the amount of light falling on a scene and tell you what camera settings you should use to achieve proper exposure for that scene. You do that by inputting two out of the 3 values from the exposure triangle and the meter will tell you the correct value for the 3rd one.

Smart Vision Lights is a leading designer/manufacturer of LED illumination, fiber optic light sources, and filters for industrial and scientific ...

For any type of constant light, which includes natural light, you’ll use the meter in Ambient mode. Often that mode is represented by a little Sun icon ️️️☀️. In ambient mode, once you’ve set your ISO and either your desired shutter speed or desired aperture, you can then take a reading or even hold the reading button and move around to see if the light meters differently at different areas of your scene.

A light meter definitely saves time though, especially when you start tweaking/moving your lights around and wanting to make sure that you’re staying at the same exposure.

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Backlights come in many colors. Monochrome LCDs typically have yellow, green, blue, or white backlights, while color displays use white backlights that cover most of the color spectrum.

If the frequency of the pulse-width modulation is too low or the user is very sensitive to flicker, this may cause discomfort and eye-strain, similar to the flicker of CRT displays.[27][28] This can be tested by a user simply by waving a hand or object in front of the screen. If the object appears to have sharply defined edges as it moves, the backlight is strobing on and off at a fairly low frequency. If the object appears blurry, the display either has a continuously illuminated backlight or is operating the backlight at a frequency higher than the brain can perceive. The flicker can be reduced or eliminated by setting the display to full brightness, though this may have a negative impact on image quality and battery life due to increased power consumption.

This reflector bends the light, keeping the Light guide straight and the beam profile uniform. It also keeps the working distance as short as possible. An ...

Uniformlight meaning

When you’ve metered once, you can change the values that you started with and the 3rd value will be adjusted automatically. Beats trying to the the math in your head, and saves you from re-metering at the different value unnecessarily.

Simple types of LCDs such as those used in pocket calculators are built without an internal light source, requiring external light sources to convey the display image to the user. Most LCD screens, however, are built with an internal light source. Such screens consist of several layers. The backlight is usually the first layer from the back. Light valves then vary the amount of light reaching the eye, by blocking its passage in some way. Most use a fixed polarizing filter and a switching one, to block the undesired light.

A camera light meter provides an exact exposure measurement, informing the photographer of precisely what shutter speed and aperture they should use for any ...

Many types of displays other than LCD generate their own light and do not require a backlight, for example, OLED displays, cathode-ray tube (CRT), and plasma (PDP) displays.