Light Meter Reviews – An Introduction

Posted: August 4, 2014 in Light Meters, Reviewed - Good Performers
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Introduction

Light meters are an essential tool for anyone involved in the lighting profession. The human eye lies to us with its unique capacity to invisibly correct for brightness variations, while the brain fills in missing pieces and compensates for color variations. For professionals, it is important to see through this biological variability to understand what we are actually looking at. One might ask why, if observers are compensating so readily, is it necessary to have objective understanding? These are the five reasons I feel having sufficient light metering is a critical tool for lighting professionals:

  1. We often don’t see what is harming our visual performance. Just because we are not physically feeling pain, or aware of anything in our lighted environment harming our ability to perform, does not mean that we are performing well, or that the light we are living under is of good quality. Issues of color distortion, unsuitable illuminance levels, flicker, spectral distribution/content, and lack of or too high a contrast within the visual environment are often hidden behind what otherwise seems acceptable lighting conditions. These variables cannot be appraised without appropriate instrumentation.
  2. Lighting has an impact beyond vision. The spectral content of the light we work and play under has an impact beyond vision alone. This includes physical impact, as well as photo-biological impact. UV light can damage the retina, while near UV, or blue light effects our melatonin levels, while light levels themselves have an impact on our bio-rhythm. There are several biological responses to light we are unaware of visually, that has an impact on our physical sense of well being, and ability to perform and heal. The content of the light presented to occupants of any space must be understood, requiring test equipment sensitive enough to the characteristics of light that have these effects. The effect of light on human health and performance is a rapidly growing field of concern. To participate in this requires a scientific approach to reach beyond the emotional subjectivity of this topic, into the heart of light itself.
  3. Light and Color coordination is impossible without knowing specific light source characteristics. Looking at light fixtures and waving them at walls to make subjective decisions is acceptable when all of the sources in a space are of the same form, or of similar character. This may also work when applying one light source throughout a space. However, most every space, indoor or out, is lighted by several light sources and technologies, which interact to create the total lighted environment.  While some may believe their acuity in subjectively evaluating fixtures in a table top environment is accurate, for the most part, due to the reasons stated above, this is an inaccurate assumption. There is no substitute for objective data in evaluating the spectral power of a light source of fixture, and where it might fit within the blend of products within a space. The emergence of LED lighting has made this a critical part of design, as these sources present variables beyond anything experienced with standard glass bulb technologies preceding them.  Objective evaluation using light meters does not fully replace subjective evaluation, the two are complimentary to one another.
  4. Manufacturers rarely present objective data accurately. Whether intentional, or from the overwhelming task of presenting accurate information for every light source option and photometric configuration offered, manufacturers present customers what they believe is enough to make preliminary selections and evaluations, but fall short of presenting the complete picture. Adding to this is the variations in binning of LED sources, changes in light source performance over a products life, LED performance escalation, and overly generalized assumptions on the part of the product maker. The only way to see through all of this is to have test instruments and an understanding of the data they present, to verify what is being delivered. This verification can be as simple as an in-field test with a portable meter, or a lab test set up to isolate a fixture from its environment. This assumes that the data presented in specification sheets and marketing materials is accurate at all.
  5. Customers are not always right. Because lighting is such a subjectively driven industry, many customers of fixture and light source producers are held to decisions made by those who have not applied an appropriate evaluation procedure, leading to in-field issues that unprepared manufacturers will find themselves victimized by. Only by fully understanding and knowing how a light source or luminaire is performing, with proper tools for evaluating products as they are made, delivered, or have performed over time, can a manufacturer legitimately defend themselves from subjective judgement. Not only do proper meters expose performance issues, they also verify that a product is performing as promised. Better yet, promises made using objective backing are far more reliable and less likely to lead to dispute. From design process tests and independent verification to quality control and in-field application verification, there is no substitute for solid data collection using a precision light metering system.

Light Meters Considered

For the purposes of the reviews we will be providing here, there are core characteristics of  good metering that need to be carefully weighed against costs involved. The Light Meter Reviews provided here are not going to dive into the ultimate NVLAB accredited facilities equipment costing hundreds of thousands of dollars, absorbing tens of thousands of square feet. These reviews will be of instruments and meters costing a few hundred to under $6,000 for the most part. The focus will be on meters that are reachable by any consulting firm through small to medium manufacturer. These reviews will also be founded on personal testing, from direct experience and use of the product in question. For this reason, there is a pre-qualification of this body of work: If I am not provided a sample to test, or have not purchased one for my own use in one of my companies, or for my customers, I will not be including them in these reviews. A further qualifier is that, if after testing a meter, I find it to be unsatisfactory, or of little use, I will not include it in these reviews. I recognize that my own tasts and needs may not be aligned with every meter producer, thus, subjective and objective review of mismatched product is unwarranted. Therefore, this does not mean that there are not other meters of excellent performance, or that the ones in this review are all inclusive of all available in the market. So, for those who have either not been reviewed from lack of my personal exposure, there are two options. 1.) Send me a meter to play with and evaluate, which I will and include in future issues here, or 2.) Remain silent, as I will not be held responsible for not testing a product I was unaware of, or found of dubious value. Their are too many games being played in the marketing and sales of light meters to get in the middle of it all. I will warn anyone involved, prices will be included here, as I do not believe the game of “Call for Quote” has a place in this universe of web information exchange and instant sales. We are all busy people, when we need a tool, we rarely feel the need to waste days going in circles just to find the price for the product is beyond our budget.

Past Reviews 

As a reminder, I have already include a review of the Flicker Machine which we sell at Lumenique for a small amount. This has proven to be a handy device requiring very little effort to evaluate whether there exists visible flicker in the light an individual tester is exposed to. While this does not produce a specific objective data point that can be used to evaluate potential photo-biological issues, it is a tool that enhances subjective observation.

I also presented a quick review In Retrospect of old methods, which laments the passing of our innocence.

These are perhaps the simplest reviews I will include, save one more, for the Amp Probe LED light meter, which I will present first, as a simple, low low cost, must have in the bag light meter for anyone whose ever wondered how much light was falling around them.

Last Notes

For the purposes of clarity, I am not going to go off into deep analysis of any meters specification and ultimate evaluation of the technical details in comparison to other meters on the market, or against some grand industry standards cooked up by the calibration nerds. If you are considering any purchase of a light meter, I suggest you first determine needs, then tolerance for error, then specifics you wish to obtain from that purchase. With that, everyone should research each meter available in detail, compare specifications, and make decisions based on these criteria. This is not the place to have someone qualifying a product in generalized terms, as each individual’s needs vary. If anyone feels they would like more detailed evaluation of any of the reviewed meters related to their specific needs, please feel free to contact me off-line, and I will offer what I can, knowing more specifically what you are looking for.

 

 

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