Daylight Technology
Lumens & Lux

Lumens (lm)
Lumens, also known as “luminous flux”, describes the amount of light that is emitted from a light source and radiating equally in all directions. It is the measure of the perceived brightness of a light source as it appears to the human eye.

Lumens do  not change with distance; whether standing at 1 metre or at 10 metres from a light source, the light source is giving the same lumen output.

Light bulbs are best measured in lumens because the light from a typical light bulb is attempting to cover 360º degrees. however, light bulbs usually achieve ~320º degrees.

Lumens & task lighting
Lumens measure the amount of light that is emitted in all directions. As a result, the lumen value is  not indicative of the amount of light that is directed at the work surface. When choosing a task light, the lumen value can be misleading.

Lux

Lux values represent the actual amount of light on a surface or defined area at a given distance. It is the most accurate way of measuring the real light output of a lamp on the work surface.

– Lux values must always be associated with a distance (the same lamp measured at 15 cm will be brighter than at 30 cm)
– Lux values are measured using a Lux Meter at a fixed distance:
– For Task Lamps we measure at 30 cm (12″)
– For Magnifiers we measure at 15 cm (6″)

The Lux value quoted is the maximum value at the brightest point on the work surface, below the centre of the shade.

In summary

Lumens is the measure of light radiating in all directions equally and therefore does not indicate the amount of light falling on the work surface.

Lux is the actual amount of light on your work surface. When comparing different lamps, Lux is the value to look for to determine which has the highest output onto the work surface, provided that Lux is measured at the same distance.
How much Lux do I need?

Daylight™ recommended light levels (Lux)

On a bright clear day, the typical outdoor light level is approximately 10,000 Lux. Inside a building, close to a window the light level may be reduced to approximately 1,000 Lux. Away from a window it may be as low as 100 Lux. Therefore, additional lighting is necessary to compensate for low light levels, to enable a task to be undertaken to the required level and to prevent eyestrain.

According EN 12464 Light and Lighting (Lighting of Workplaces), the minimum illuminance for normal detailed activities is in the range of 500 – 1,000 Lux, depending on the activity.

For more detailed tasks the light levels need to be higher (1,000 – 2,000 Lux). For very detailed & precise tasks the light levels need to be higher still (2,000 – 4000 Lux) or in some cases, even higher.

 

Our recommended light levels for different types of activity are indicated below:

General tasks: Reading, general drawing work, mechanical assembly, simple craft work
Illuminance Lux Level: 500 – 1,000

Detailed tasks: Detailed drawing work, fine painting, mechanical & engineering work, electronic inspection, quality control, testing and adjustment, sewing and crafts, beauty treatments, nails & pedicure, tattoo work
Illuminance Lux Level: 1,000 – 2,000

Very detailed tasks (with low contrast for prolonged periods): Precision mechanical / engineering work, laboratories, very fine painting & artwork, very fine sewing and crafts, very detailed beauty treatments
Illuminance Lux Level: 2,000 – 4,000

Precision and very low contrast visual tasks for extremely long periods to a very exacting standard: scientific laboratories, very complex mechanical & electronic assembly, hospital operating theatres
Illuminance Lux Level: 4,000+

At Daylight, Lux levels are a key part of our product design to ensure that you have the optimum amount of brightness for the task at hand.
Colour Temperature (Kelvin)

Colour Temperature (Kelvin)

The colour temperature is measured in Kelvin (K) and refers to the colour temperature of a light source as it is perceived by the human eye.
The colour temperature is obtained by heating a block of carbon to a specified temperature and observing the colour it glows.

For example:
A colour temperature of around 2,700 K gives off an orange colour. Similarly, a sunrise or sunset gives off a very warm feeling.

A colour temperature of around 10,000 K gives off a blueish colour. Similar to a blue sky which gives off a cool feeling.

A colour temperature of between 5,500 K and 6,500 K gives off a white colour, known as daylight. This is similar to a sunny day, when the sun is high for example at 12 noon.

The industry terms used to describe the different colours of artificial light are:

Colour descriptionKelvin valueWarm white2,700 KCool white4,000 KDaylight5,500 K to 6,500 K

At the Daylight Company, all LED Lamps & Magnifiers are built to produce a daylight colour temperature of 6,000 K.
Colour Rendering Index (CRI)

What is CRI?

The Colour Rendering Index (CRI) is a scale from 0 to 100. CRI is used to measure how accurate an artificial light source is at revealing colour in comparison to a natural light source (eg: the sun). A high CRI indicates that a lamp is better at rendering colours truly, a value of 100 CRI represents the sun.

The higher the CRI value (also called CIE Ra), the more accurate the colours will be.
Dioptre & Magnification

Dioptre & Magnification

Dioptre refers to the curvature of the lens. As the dioptre increases, the lens becomes thicker and the curvature greater. As the curvature increases, light rays are redirected to fill a greater portion of the viewer’s retina which makes the object look bigger.

Power (magnification) refers to how much larger an object is made to look through a magnifying lens. Power is typically indicated by an X such 2X or 4X.

For example:
A 3 dioptres lens makes an object look 75% larger,
A 5 dioptres lens makes an object look 125% larger,
An 8 dioptres lens makes an object look 200% larger,
over and above what the unaided eye already sees.
ESD

What is ESD?

Electrostatic discharge (ESD) is the sudden and momentary flow of electric current between two objects caused by direct contact, or an electrostatic field. The term is used in the electronics industry to describe momentary unwanted currents that may cause damage to electronic circuits & components.

ESD is a serious issue in solid state electronics, such as integrated circuits and steps must be taken to prevent it. Semiconductor materials such as silicon can suffer permanent damage when subjected to high voltage; as a result all products and equipment used during the assembly or inspection of PCB boards should protect from ESD damage.
Environmental Information

RoHS
Restriction of Hazardous Substances (RoHS) is an EU Directive that came into force in 2006 and applies to Electrical and Electronic Equipment.

The Directive restricts the use of six hazardous materials in the manufacture of various types of electronic and electrical equipment. It is closely linked with the Waste Electrical & Electronic Equipment (WEEE) Directive which sets collection, recycling and recovery targets for electrical goods and is part of a legislative initiative to solve the problem of huge amounts of toxic electronic waste.

The purpose of the Directive is to severely restrict the use of substances that are considered hazardous to the human health and to the environment, in electrical products.

It is a legal requirement that all Electrical Products sold in the EU comply with the Directive.

The six substances covered by the legislation and the limit for each are show in the table below:

Substance Limit

  • Lead< 0.1%
  • Mercury< 0.1%
  • Cadmium< 0.01%
  • Hexavalent Chromium< 0.1%
  • PBB (flame retardant)< 0.1%
  • PBDE (flame retardant)< 0.1%

The Daylight Company is concerned with the directive for its lamps and luminaires but it does not apply to our range of accessories; floor stands, table bases, cutting mats, clamps.

The Daylight Company has signed agreements with its suppliers and they are required to produce products that comply with the Directive.

ROHS is now part of the CE Marking Directive and does not require its own mark.