logo metric Consulting, Workshops, Light Quality, Sales  

There is more to lighting than meets the eye

Les Kacev is passionate about lighting education, measurement and the quality of light. He has run seminars, workshops and webinars for utilities, associations, universities, LED manufacturers, vendors, distributors, and conferences. A few examples follow

The human eye is truly our window to the world. Not only does it contain rods and cones which stimulate our vision, but it has recently been discovered that the eye contains a variety of intrinsically photosensitive retinal ganglion cells known as ipRGC which are involved in non-visual functions. Light and light quality play an immensely important role in stimulation of ipRGCs and in so doing determine our mood, sleep patterns, productivity, health and  general wellbeing. Light exposure plays an important part in our mental health.

Not only does light [natural and artificial] affect humans, but its impact on fauna and flora is only now being appreciated. Its influence on mammals, birds, bats, insects, fish and plant life has opened up a new branch of science.

Lorem ipsum dolor sit amet, contuer adiping elit, sed diam nonummy nibh euismod.

Lorem ipsum dolor sit amed sed diam nonummy nibh euismod tincidunt ut.

Duis autem vel eum iriure dolor in hendrerit in vulputate. Nulla facilisi. Quisque sem mauris, ullamcorper ac, gravida id, mattis id, sapien.

Scroll To Top

Apps for both Apple and Android smart devices are updated continuously and new applications are always in the works.

For the Standard and Flagship models, go to the Apple or Google store and download the free Spectrum Genius Mobile App. Open the app on your smart device. Open SGM
  • For the Standard and Flagship models, go to the Apple or Google store and download the free Spectrum Genius Mobile App. Open the app on your smart device. Open SGM
  • Click on Single and select Parameters
  • Click on MEASURE and view results
  • Click on MEASURE and view results
  • Click on MEASURE and view results
  • Click on MEASURE and view results
  • Click on MEASURE and view results
  • Click on MEASURE and view results
  1. For the Essence model, go to the Apple or Google store and download Spectrum Genius Essence.

open it

select it


Working with filters, gels, lenses, diffusers, window treatments and the like can be a haphazard business. From experience, many in the industry have a good gut feel as to what to choose. Now we have the tool and technique to make the choice more scientific.


Indoor horticulture is a rapidly growing industry in the United States and elsewhere.
Many factors contribute to plant health and yield. Soil quality, nutrients, temperature, humidity, air circulation and light all play their part. Our focus is on lighting, the energy source for photosynthesis.
The introduction of LED light sources has opened up a whole new world in indoor horticultural lighting. LED lights are much easier to control and can be programmed, leading to the ability to vary color, spectrum and intensity to suit growth cycles and seasonality. This increased sophistication has led to a critical need for light measurement as optimum conditions are developed and tested.

With Lighting Passport and Spectrum Genius Agricultural Lighting, any light source, not only LEDs, can be measured and evaluated!
PAR – Photosynthetically Active Radiation defines the wavelengths which are most relevant to plant growth, but different wavelengths are more or less active.
What is important to plants is the Photosynthetic Photon Flux Density – PPFD and Yield Photon Flux Density – YPFD.  Lumens are for humans, PPFD/YPFD is for plants.

Many characteristics of light play their part in stimulating plant growth.
Spectral Power Distribution – SPD, Correlated Color Temperature – CCT and location in the CIE chromaticity diagram, intensity and more.
Lighting Passport [LP] and Spectrum Genius Agricultural Lighting [SGAL] make measurements routine and evaluation/analysis more scientific, taking the guesswork out of horticultural lighting and is a “must have” for lighting manufacturers, growers,
consultants, researchers and anyone else involved in horticultural lighting.

SGAL-1 LP 1 Menu.jpg

We are excited to announce the release of Spectrum Genius Studio [SGS], the App which works together with the Lighting Passport [LP] spectrometer to determine the color properties of lighting for the TV/Broadcast and movie industries. SGS is based on the Television Lighting Consistency Index [TLCI] which through EBU Tech 3353 is the UK and European standard. The US has not adopted a standard yet but is tending toward TLCI.

TLCI categorises studio luminaires into five levels

TLCI uses a Color Checker (Split MacBeth) chart [1] to compare the color rendering qualities of a measured luminaire to a benchmark based on Correlated Color Temperature [CCT] and assigns it a number between 0 and 100 [2] describing its color quality with 100 being perfect. The CCT is then listed [3]. The assigned number falls within the 5 categories above from excellent to poor. TLCI incorporates a number indicating deviation from the Black Body Curve (Planckian Locus) [4]. It also indicates camera corrections in Lightness, Chroma and Hue in 12 color categories to better align luminaires to cameras [5]. A graphic of the Spectral Power Distribution and the TLCI reference spectrum [6] gives an indication of the radiated light as opposed to the reflected measure shown in the Color Checker chart.
Additional references can be manually selected and users can add their own Television Luminaire Matching Factors [TLMF] for optimal balancing where more than one light source is used. To Quote Mike Wood: "If TLCI is a tool for manufacturers to use in designing a product for television use, then TLMF is a tool for practitioners that allows the prediction of real world mixing and matching of different sources before getting in the studio, when it is often too late to change."
SGS produces all these charts and numbers at the push of a button. In addition, beneath each color patch in the Color Checker, it lists a TLCI number [7] so lighting practitioners can evaluate luminaire performance for the entire color palette. This is extremely useful with less sensitive or poorly calibrated monitors.
SGS is the only currently available mobile App which comprehensively covers all aspects of TLCI as opposed to just calculating a single TLCI number. We expect that the combination of LP and SGS will create a scientifically accurate and extremely simple approach for matching cameras to light sources for both manufacturers of studio lighting and DPs, lighting designers, and all other lighting professionals involved in color quality in TV/Broadcast and movie production.
SGS is currently only available for iPad or iPad mini.
For those of you who already own a Lighting Passport spectrometer, please go to the Apple Store, search for Spectrum Genius Studio in the iPad section and download. If you have not yet purchased your LP, please place your orders through LEDmetric.

spectrum genius TLCI
spectrum genius TLCI
spectrum genius TLCI