Posts Tagged ‘Lighting’

After reviewing a range of different metering choices in actual use, I compiled a summary of findings, as well as my own personal subjective ratings of features and overall utility as a lighting professional. This chart is the collection of all findings in a simple comparison table for those who find this useful (like me):

The Meter Comparison Table in .pdf format.

Note that all of the meters tested were shown to deliver accurate results when testing LED products, as well as conventional lamps. This is not always the case. Many older meters do poorly under LED light sources, either delivering unreliable results, or unstable readings. One example of this are the obsolete Minolta meters manufacturer before LEDs had entered the market. These often deliver CCT results that are far enough off more current meters as to render them essentially useless. Also, some LED products flicker at a frequency that creates moving readings, which never stabilize enough to be readable. The meters I have that exhibit this behavior were excluded from review completely, for obvious reasons.

This is by no means a comprehensive review of all the meters available to designers and engineers. I could have scoured web sites and pulled down more data to include objectively from indirect information. However, that was not my intention, and like the results I get from testing actual products against published data, there is no substitute for directly using and testing any product. The problem for most of us is that testing every option before buying is just not possible, or practical. So, with that in mind, and reflecting the fact that I have both collected more than my share of instruments and put them to use, and have had access to others purchased for and with customers, I offer the reviews as they stand. In this, simply regurgitating what I get from web sites would only pollute the results, as anyone can do that, as that is how I came to purchase those products I have, for both good and bad results. I hope that this this is of value to those making your own decisions, hoping to avoid some of the redundant purchasing decisions I have, that has led to having this many meters collected to review.

That all said, if anyone has a meter they feel was unfairly excluded here, that would like to be added, I offer this. Send me the meter and give me a few weeks time to play with it, and put it to use in tests we are completing on a regular basis. This includes whatever software is required to create a complete picture of the product in actual use. I’ll add what I find to the meter reviews by adding an entry for the specific product, and update the summary comparison table before returning the meter – unless I find I can’t live without it and find myself compelled to add to my collection – which we can discuss at the time.

This is the Lighting Passport Flagship set. Includes case and accessories in a neat package.

This is the Lighting Passport Flagship set. Includes case and accessories in a neat package.

I first saw this device at Light+Build Frankfurt last fall. I was impressed enough to find one added to my collection of tools. The Asensetek Lighting Passport is a unique product in several ways. First, it is essentially a meter head (where the cost is), coupled to an iOS or Android device that does all the computational and display work. The lighting head has a nifty slide action receptor cover, so there is nothing to come off or get lost in a bag or pocket. The measurement range is as broad as any of the other spectrometers tested here, plus some. Not only does it produce the expected spectral power distribution, CRI, CCT, CIE 1931 and 1976 coordinates and illumunance in lux and Fc, it also delivers CQS values. There are several additional data points worth singling out:

  • Du’v’ value. This is the missing piece of the CRI value we have always needed and were never provided. This tells you whether the light source is above or below the black body line. A positive value indicates the source will appear on the yellow/green side, while a negative indicates a tint of magenta will be present. When you put two sources side-by-side of the same CCT and CRI/CQS, you will see these differences clearly. Now, with the Du’v’ value, the difference will be quantified and usable in future comparisons when you don’t have both sources in the same room at the same time.
  • S/P (Scotopic/Photopic) value. This is the value that will drive future lighting decision making. This indicates how well a spectral power distribution satisfies both the scotopic and photopic visual response curves of the human eye, which combine to deliver mesopic vision, and is the center of most current thinking in explaining why we find one source more visually stimulating and clear over another. This is also the value described by the IES in TM-24 13, where the application of S/P ratios can be used to reduce energy use, by taking advantage of the dynamic advantage of high S/P ratio light sources ability to generate increased visual acuity at reduced illuminance levels.
  • PPFD, or Photosynthetic Photon Flux Density. This is the amount of light in umol/sec meter sq. in the spectral distribution (red and blue peaks over human vision in yellow green) that is used in lighting of plants. While not everyone will find this useful, when you need the data, this meter delivers it. Its also an interesting value when looking at how an artificial source and daylight compare, but that’s for another discussion.
  • FWHM color value. This is an interesting value that shows the width of a products light output to 50% of its relative power in wavelength. This is an indicator of how broad the total power distribution is, and is very interesting when comparing two sources to one another.
  • Peak and Dominant wavelength. Peak wavelength tells you where the highest output of a product is centered (in color), while dominant wavelenght tells you where it sits in CIE coordinate positions.
  • ANSI bin and CIE McAdam Ellipse values. Based on a preset standard value for the CCT a source is nearest, you can see where the measured product sits within the standard ANSI color bin, and how far off in McAdam steps it is from the CCT standard center. These are excellent tools in comparing two sources to one another of the same CCT and CRI, and along with the Du’v’ value will provide insight into what to expect in application of the products, in relation to color differences between two products.
  • Multiple source comparisons and multiple readings of a single source. The Lighting Passport allows multiple readings to be taken and compared, or collected into database. This provides direct comparisons on the meter itself of two products to one another, or of multiple readings taken in sequence within one test session. This not only allows comparisons to be made objectively on all metrics, it provides a tool for evaluating color shift over light distribution patterns. For my own use, using this meter on a goneometer rig means I can not only collect the illuminance data necessary to define light distribution, but see how the color values shift throughout that light pattern.
  • Light transmission accessory software. This small utility program is great for evaluating light transmission of materials, generating a simple report of the materials properties in both total transmission, and spectral transmission. This is a tool that every lighting meter used for design should have.
The range of information available to view on screen is excellent, clear and easy to read.

The range of information available to view on screen is excellent, clear and easy to read.

So, with that all covered, one would have to say that the product is impressive, and spot on target for what lighting professionals need in a portable and small lab environment. But, that would be missing some even more interesting features of the Lighting Passport that puts it head and shoulder ahead of the rest. Like this:

  • Separate metering head operated by wireless (Bluetooth) connection. The small head size means not having the meter body height involved in the placement of the sensor, which can be an issue in task illuminance readings, where the light source is inside 36″ of the target surface. In all the other meters with an integrated head, the body height of the meter gets in the way of gaining an accurate measurement. The Passport includes a small stand attachment that allows the meter to be set where you need it, then stand back to eliminate the influence of being in proximity of the measured result.
  • Works with ANY iOS device and Android 4.4.2 device, identically. That means phones, tablets and Pod music devices. So, if you already have an iOS or Android phone, you don’t need anything but the meter head, which slips into a pocket, to take for on-site measurement. This also means that use of a tablet sized device allows the meter and its output to be viewed easily by several people in a room, even projected onto a video monitor. In my case, I’ve connected the sensor head to my Samsung Note 3, and taken readings in a room with people viewing the results on an HDTV connected to the Note 3’s USB connector. This takes education sessions, product evaluation sessions, and general discussion and presentation to a level no other meter can match. Here’s another neat feature of this product – the interface software is open platform based, which means those with the need to create a custom interface for specialty evaluations have that available to them. This also means that updates to operating software through Android and iOS app outlets will make keeping the product current will be far easier than anything proprietary products can match.
Separating the meter head from the display is an outstanding feature that allows it to be used in a wide range of applications, and not interfere with readings.

Separating the meter head from the display is an outstanding feature that allows it to be used in a wide range of applications, and not interfere with readings. The little clip to the left attaches the head to any tablet device with a secure clamp feature.

The lighting head is compact and when mounted on its provided stand, stable for remote measurement. It is also the only part you have to carry with you to a job site, should you already have the software installed on a smart phone.

The lighting head is compact and when mounted on its provided stand, stable for remote measurement. It is also the only part you have to carry with you to a job site, should you already have the software installed on a smart phone.

The meter and its design is impressive enough to be a reason to consider it, and is very usable as a stand alone. However, on top of this, the Spectrum Genius software creates an expanded opportunity for evaluating all of the collected data in a single screen, and compare sources, or multiple readings at once. This adds a layer of utility to the metering system that really enhances its use for those doing a lot of work in evaluating application results or products for consideration in specification. It also generates very nice reports, exports data into spreadsheet worthy data sets for use in other calculations. In my case, I export the data set from multiple reading sessions to create photometric reports that are used in conjunction with the spectral reports to create all of the same data one gets from an LM-79 report, in-house, of any product I can get my hands on. That means I have been able to compare LM-79 reports provided by manufacturers to test results of product samples – with interesting results. I can also provide preliminary LM-79 evaluations of products in the design phase for customers, before they  are completed for final testing at an independent accredited lab. No more ugly surprises and re-testing issues when a product does not perform as needed or expected.

The Spectrum Genius software puts everything in one place, making evaluation quick and easy to see.

The Spectrum Genius software puts everything in one place, making evaluation quick and easy to see.

The Lighting Passport can be found in the market under the brand name Asensetek, and is sold in the USA by Allied Scientific Pro. The prices are wide open, you can order them on line, and with a range of between $1,500 to $2,500 for the meter and its attachments, plus software for free to $500, this package delivers a massive bang for the buck. This pricing is less than some of the high end white-light illuminance meters on the market, while delivering far more information. The product can also be calibrated, so can be used for precision applications and  other uses where it is important to have backing for the data collected.

Printing a report from the software to provide to customers or store as a record for comparisons is a nice feature

Printing a report from the software to provide to customers or store as a record for comparisons is a nice feature

In conclusion, I use the Lighting Passport as my go-to meter choice, and have found very little to complain about. It’s not perfect:

  • The software is a little glitchy in its display, but not so much that I find it an issue.
  • The software also creates a graphic error when creating a report using CQS, as it overlaps the data from R values with the Q values from Q7 thorugh Q15, which is truly annoying. I’m hoping this is resolved in future software updates.
  • The software also uses a dongle for security, which some will hate. I like it, as I have the software installed on both my laptops and desktop, and can move the dongle between them for use anywhere. others will find the tether objectionable I am sure.
  • The transfer of data from the meter to the software is through email or iTunes over wireless, although you can upload the data by file explorer in Android devices. This is fine with a smart phone, and works just fine with the iPod device provided in the Lighting Passport Flagship set (with wireless availability). It would be nice to be able to connect directly from a desktop through wireless to download stored files, but this is not a serious problem, and more an issue with the devices themselves – separate of the meter system. I find no compelling need to operate the meter from a desktop, as the remote head and hand held ergonomics of the data collecting device are just fine. In a lab space, use of an Apple mini-pad or other tablet device works quite well, and eliminates the need to have a computer dedicated to lab duty where it sits unused most of the time.
The package of components are well thought out, and well designed. Quality is very good.

The package of components are well thought out, and well designed. Quality is very good.

Overall, for anyone looking for a portable, high quality spectrometer/illuminance meter product, the Lighting Passport is going to be hard to beat. At its current price, I would say impossible to beat actually. More on this from Allied Scientific Pro More on the Spectrum Genius Software

We have now entered the modern era, where meters are available with a dazzling array of features, at a fraction of the cost once commanded. In this case, the UPRtek MK350S, available also in a lesser featured, and lower cost MK350N version, produces amazingly beautiful results with little pain in the wallet or the head from learning to use it. You may find this also sold under other brand names, such as AIBC, or sold through outlets such as Allied and Ikan. I first saw the MK350S at Light+Build in Frankfurt. A customer of mine also saw them, and was so impressed, he purchased one and has allowed me some time to play with it and in preparation of building up a test lab for his company.

MK350S package

MK350S package

The MK350S comes with all the parts necessary to put it to work. With a bit of minor assembly, insert the battery, slide in the data/wireless card, charge it up, and its ready to go. The touch screen interface is a great feature, as is having the results readily displayed on the device itself in full living color. Their is a camera function that not only allows a picture to be associated with the readings taken, but assists in aligning the sensor when readings are taken.

This meter can deliver the entire collection of desirable architectural lighting results (with a couple of interesting exceptions we will cover in a moment.) The output on the screen can be configured to show:

CCT
CRI
Spectrum view
CIE 1931 view
CIE 1976 view
LED Bin position (within a standard ANSI bin for the CCT reading)
Footcandles and Lux
Dominant and Peak wavelength
Comparison of two light sources
Associate a photo to a meter reading
Purity

The data can be stored on an SD card for use within the companies basic software, which duplicates the presentation of the device itself. Overall, the product runs in the $3,100 range at the advanced level, while the MK350N can be hunted down for around the $2,500 mark. The extra $600 produces several nice additions, particularly the lack of CRI and Purity. Further, the MK350S includes wireless communication for control of the device, where this is an add-on the the MK350N, which will bring its cost closer to the MK350S level, and still be missing the CRI function. Here is a link to a comparison of the two MK350N vs. MK350S.

mk3503

The range of delivered outputs from the MK350S is impressive

I found the product an exciting tool. Its difficult to resist walking around taking readings all over the place and looking at the results. It’s great having this all in hand, without cables connected to a laptop, and a display bright enough to be seen in daylight conditions. The meter fits well in the hand, and goes a long time on a charge. Overall, this is a great new step forward in bringing accurate, relevant lighting data to specification level decision makers and evaluators.

LUX.G image from AIBC web site

LUX.G image from AIBC web site

There is another unique feature provided in the MK350S, called LUX.G that generates a colorized brightness ratio image of a space to illustrate brightness patters. This false color imagery helps the user see the brightness patterns more clearly, and is rather interesting. Not sure exactly how useful it will be, but it is certainly something to look at.

This all said, I have a few nits to pick with it.

No CQS. With CRI under attack, and likely to be replaced soon, likely with the CQS or other similar system, I wonder how they will deal with the new standard when it emerges, or will this be a matter of having to replace the product itself?

No P/S Ratio. It seems an easy addition to include the Photopic/Scotopic ration function, considering how this is becoming a topic of discussion for future approaches.

No McAdam Ellipse evaluation in the bin function. With the data existing in the system as it sits, there is no reason this comparison could not be included.

Not wild about the software/wireless registration loop. The company makes every new user jump through a few hoops to get their software up and running, and the wireless card to work. The real problem here is that the wireless card must be functional to access the memory card for storing data, so until that’s done, there is no way to get the data from the device anywhere else. But that’s okay, since the data is useless without the software, which also requires a registration loop.

Integrated display on top with fixed light sensor is not ideal. The fact that the sensor is permanently stuck in the end of the meter, and the display is on top, means that in lab or tripod mount uses, the meter must be connected to a computer to see the results. Further, the sensor at the end of the meter means reading some angles must be done blind, then read, which renders the camera assisted aiming moot. While we’re on that topic, the camera position on the head is enough offset of the sensor, that measuring close up objects is a bit odd, requiring you offset what you see to get the sensor properly centered. It would be a nicer device if the sensor head popped off for hard-to-read, tripod, and lab application.

These are all minor issues in the bigger picture, and will likely be smoothed out as the product is applied over time. This is a level of performance, and superior in the GUI over much more expensive systems, like the Minolta CL500, whose display is poor, or others where connection to a computer is necessary to come even close to what is displayed in this handheld device.

More on the MK350S from UPRTek and from AIBC

To compliment a standard light meter, which does a fine job collecting illuminance information, I sought a low cost solution to evaluation of color data, specifically CCT, spectral power distribution and CRI. My goal was to find a product under $2,000, that could be calibrated, that would deliver me color information simply and without a large amount of special technical effort. I found that in the Mightex CCD Spectrometer. At a base price under $1,700, it fit the budget nicely. Of course I added a few accessories to it, and paid them to calibrate the meter with a fiber optic mounted cosine sensor, which increased the total invoice to a touch beyond the $2,000 target… However, in the end, I found the results to be exactly what I was looking for – almost.

Mightex CCD Spectrometer

Mightex CCD Spectrometer

The CCD based (same technology as high resolution cameras) spectrometer is that it holds its precision over a wide range of temperatures and for long periods of time before requiring re-calibration. While the software is not as slick as the previously mentioned Orb Optronix SP-100, it is certainly functional, and delivers the information I wanted from it. It calculates CCT and CRI, and presents it in both graph and graphic formats. The spectrometer’s raw data can also be downloaded in a file format usable for evaluation in spreadsheet form.

Connecting the meter to a computer is as simple as plugging in the USB cable, which also provides the power to the unit. I use a fiber optic cable from a cosine correction end attachment, as this allows me to leave the box and its connection to a laptop on a table, while reaching up to ceiling products, or fixing the reception head to a holder for lab testing on the goniometer.

Mightex CCT and CRI screen output

Mightex CCT and CRI screen output

mightex graph

Mightex Graphic output

The output reports are very easy to read, and show all the information I need them to, including individual R values in the CRI calculations, and pertinent color coordinates in both numeric and graphic format. For the money, it delivers most of what much more expensive equipment provides, in a very simple to use and apply unit. The software does take a few moments to figure out. Of particular issue is selecting an appropriate sample rate, sample number, and integration time to create the most accurate CCT and CRI result. This is usually done by experimenting with various settings in the operating software until a smooth spectral distribution curve is created. A smoothing function can also be applied to improve results.

This is not going to be a user-friendly device for anyone who is not familiar with photometric testing using spectrometers. Failing to apply the proper settings creates wildly erroneous results that will be confusing to those who are not familiar with what causes them.

One missing piece that needs mentioning, is that the Mightex does not produce illuminance values in any form usable in architectural lighting. The data can be read in absolute irradiance as uW/cm2,  which can be translated and converted to other forms. I needed this exact data for one customer in the UV light curing business. However, for the most part, the data is most useful in spectral power distribution evaluation as presented without bothering with any such effort. For my uses, other meters provide me the photometric data I need without relying on the Mightex for use beyond color evaluation and performance. Overall, this is a nice tool for those looking to create a low cost lab setup. For the architect, lighting designer, or electrical engineer looking for a portable light meter solution with CCT and CRI capability, it is probably not an ideal solution.

More on Mightex Systems

When it came to setting up a lab with a proper precision meter for collecting and evaluating color (CCT) and color quality (CRI), as well as measuring transmission, luminance, radiance, irradiance, and illuminance of light sources and fixtures, I chose the Orb Optronix SP-100. This was done in partnership with a customer, for whom we set up a complete lab with goniometer we built for the customer, for testing their ongoing products as part of a design services agreement. In time as the customer grew in their own capacity, the entire rig, along with the data processing protocol we developed over several years, was transferred to the customers own facility, where staff was trained to complete their own tests in-house, where this is still in use today.

Orb SP100 and gonio setup

Orb Optronix SP100 and gonio setup

This Orb Optronix is an excellent meter on its own. It includes a laser aiming feature that seriously improves setup accuracy and reduces the time it takes to align the test product with the sensor. The SP100 was very easy to learn, and generated usable data from its first day in use. It did take some time to sort out integration times (time the meter is given to process incoming light before recording a value) and to recognize when the dats itself is in error due to a lack of time allowed, or number of samples per reading was inadequate. This is truly a lab grade product, and the price reflect that focus, placing it at the top end of the budget range (>$9,000 to start), which can balloon for those adding more features, adapters, training and other services.

I would not consider this a product for a consulting firm looking to evaluate lighting products for specification consideration. While the meter itself is a nice size, and exceptionally accurate, its most at home in a fixed lab, operated by individuals knowledgeable and focused on setting up proper test protocols. There is also one missing bit of data from this meter and its software – that is Illuminance  in the form of Lux and/or Foot-candles. Also missing are candella, and lumens. This requires taking the raw data, in other forms, and converting it to these values. In my case, we used spreadsheets to create candella data from illuminance in Lm/M2 then used other programs to convert candella distribution data derived to photometric files, which created the lumen output and other photometric values we needed to relate to architectural use. This is not specifically a fault in this system, it simply reflects the intended purpose of this product to obtain accurate lab level data.  I must qualify that we chose not to purchase the SpectralSuite product offered by Orb Optronix, which produces LM-79 output in proper photometric values, choosing in stead to save the money and do this work ourselves.

The basic software package provided with the SP100 is excellent.

The basic software package provided with the SP100 is excellent.

The software that is included with the SP-100 is excellent in its own right, providing both visual and tabular output for detailed evaluation. The operating process is very simple and intuitive, given a little time to understand the dynamics involved. For setting up a lab in limited space, their were few options within the price range of the SP-100 that would generate the quality of data we collected. However, my first work with this product was over 5 years ago. Since that time, several new products have come on the market that are both better suited to architectural lighting evaluation, and far less costly. Since the SP-100 has been moved to my customer’s site, I’ve moved on to other products to serve the requirement gap the loss of the SP-100 created in my own in-house lab operation. For my own personal business needs, the cost of the software and hardware was a bit more than I was willing to invest, especially when I considered I’d set up my most heavy use customers with their own labs, which significantly reduced demand for testing. As it turns out, advancing technology would not only solve that for me, but deliver new opportunities not possible in 2009.

For covering the range of CCT, CRI, spectral power distribution (with very fine fidelity), luminance, radiance, illuminance, irradiance, x,y and u’, v’ chromaticity coordinates, dominant wavelenght and peak wavelength of any light source, I found the SP-100 is a valuable tool.

More on the Orb Optronix SP-100

This is going to be a quick one. First of all, no matter what other meters one might own, the basic illuminance meter, with its readout in Lux or Fc remains an essential. You pull it out, press a button, get a number. The issue is with the latest generation of LED fixtures and retrofit lamps. They present a somewhat skewed spectral balance that can cause issues with older meters. For example, my trusty old (very very old) Minolta Color Meter II shows all LED sources as being roughly 200 CCT cooler than they actually are, sometimes, sometimes not. My other old trusty bag filler is a Minolta T-1H, which is great under daylight and tungsten sources, but not so good under LEDs, where  readings are off about 12% most of the time, and when exposed to LEDs with any flicker in them – the meter has a hard time finding a reading to settle on. I also have a Testo 540 digital ligth meter, which is an excellent in-the-pocket device, as it is very slim and includes a cover for the light sensor. At a cost of under $140, they are hard to beat for a simple tag-along meter for general illuminance measurement.

The flicker issue was also experienced in a more contemporary Minotla T-10MA and T-10A although to a lesser degree.

Minolta T-10MA - image from Minolta site.

Minolta T-10MA – image from Minolta site.

I used these in lab conditions for collecting photometric data and in the field. Flickering sources simply confounded getting a steady reading.  Under normal LED lights, and all other light sources, these are a great meter, with a ton of options to grid several heads together, remote and mounted head locations, various accessories and add-ons, like AC power, and data downloading, to make these a nice product… however, these neat devices do cost $1,060 for the T-10A, a bit more for the remote head T-10M, plus another $600 for software to connect it and download data via PC. For someone looking for a meter to be calibrated annually, with trustworthy precision, and no need for color analysis, this is about the best package there is, if the budget is available for it.  If you need color capability and greater integration of data collection functions, you will likely find the T-10 expensively redundant, as most color meters produce the same readings as part of their output. The T-10, however, does offer features for field studies of illuminance over an area, specifically the grid connection of several sensor heads over a wide area, that few other meters support at this price level.

More on the TM series from Konica Minolta

This leads to the one meter I use the most when all I am looking for is a quick “how many foot-candles are here” reading. That’s the AmpProbe LM-200LED.

Amp LM

The AMPProbe LM200LED

This meter provides results in Lx or Fc with a simple button press, has data hold, max level memory, and a range wide enough to cover any lighting need. The remote light sensor head is great for getting ones white shirt out of the readings. At less than $100, this is a particularly hard bargain to beat. I’ve done photo-metric tests with this product and been within 5% of independent professional photo-metric results, and have put it against a wide range of other meters to verify its accuracy and found it to be pretty much spot on, even when tested against meters costing literally hundreds of times more. The meter can take a moment to settle down to a steady reading when exposed to flickering sources, but it will, in the end, stop vacillating and give a reliable result. I suspect the low price comes at the cost of a particularly slow processor, so with that in mind, I just give it some time to get its job done. I’ve been using the meter pictured for 6 years now, with no issues at all. Its battery seems to last forever. It also has a 1/4 x 20 threaded boss in its back to mount the meter body, although I am not sure what utility that serves, since the head has no such provision. I also found it to produce reliable readings under colored light sources. However, under UV light sources, the diffuser over the sensor fluoresces, so the readings  become unreliable at anything below 420nm. One additional feature worth mentioning, is this meter includes the ability to set a zero point by adjusting a pot in the side of the meter body. I used this feature for one customer who ordered 3 meters that needed to produce as near-identical readings as possible  for a quality inspection use. We were able to accomplish this using the adjustment feature. I have also used it to set a dark zero-point in a make-shift lab condition where exclusion of 100% of ambient light was not possible.

I have had several other white light meters, some okay, others not. That said, as we have added other meters to our tool box, I find the need for these simpler meters to be less and less. As we will see in future reviews, when a precision light sensing head is added to a smart phone or tablet, their becomes fewer instances where the redundancy of a low cost meter is necessary.

More on the AMPROBE LM-200LED

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.

 

 

The recent article: LED Bulb Efficiency Surges, But Light Quality Lags states very well the findings of the DOE and others reviewing LED retrofit lamp performance. While well stated, there are severl missing dynamic issues in the conversation that need to be included if LED is to overcome the failure of the CFL to capture the consumer market it so desperately seeks to dominate.

While efficient, there has been no great interest in the consumer market to lamps with poorer quality at higher prices.

While efficient, there has been no great interest in the consumer market to lamps with poorer quality at higher prices.

The CFL lamp has failed in the consumer market for these reasons:

  1. Light quality is poor in comparison to the far cheaper incandescent lamp. This includes color quality, distribution (photometric) pattern is poor (flood type products)
  2. Appearance and fit of the product into existing fixtures – i.e. ugly to look at, stick out of fixtures, create dark spots in shades and fixture diffusers, etc.
  3. They did not last as long as advertised. When switched frequently, the life of a CFL screw base product can be shorter than a long life incandescent. In outdoor cold climate environments, some fail within a few months. In down-lights and enclosed fixtures most fail even more quickly.
  4. They cost too much compared to incandescent of higher quality
  5. They save some energy, but have so many other liabilities the consumer does not take this seriously.
  6. Flickering starts, flicker under dimming, and 120Hz strobe effects from cheap ballast designs
  7. Slow to warm to full brightness – often taking longer to get up to full light than many products are on for in many rooms (pantry, closet, hallway, etc.)
  8. Mercury disposal concerns for some

(more…)

08285I have a fondness for the halogen lamp. From the little 20W bi-pin 12V burners to the 500W double ended monsters, the combination of light quality, simplicity, toughness, light density and versatility filled a special place in the hearts of lighting designers for decades. While there were also  larger iterations of the technology reaching 20,000W, even the most halogen crazed found them to be a bit over the top, setting them aside for special applications. In my own experience, the 20W through 75W 12V burners, 15W through 65W MR16, 35 through 50W PAR36 and 75W through 250W mini-can line voltage lamps hit the spot for a wide range of focused and unfocused lighting product designs. For my personal portable lamp works, the low voltage burners, MR16 and the PAR36 lamps were my favorites. I could create live-structures (where the fixture acted as conductor) using remote 12V power supplies, allowing sculptures to be simple to the extreme.

This simple bridge design was created using building and armature wire, a PAR36 halogen lamp, and a ball bearing counter weight.

This simple bridge design was created using building and armature wire, a PAR36 halogen lamp, and a ball bearing counter weight.

When LEDs arrived on the scene in the late 1990’s, I caught a glimmer of what was to come. By the year 2002, it was obvious that solid-state would be delivering something new, and that the properties of the source technology shared a great deal with the halogen lamp from a lighting perspective, with a huge advantage – far less heat, much tougher and resistant to impact, and very long lived. The only issue was, color quality was initially poor, consistency from LED to LED was awful, and light output per individual LED device was pathetic. This required designs utilize a number of LEDs mounted to circuit boards, wired to drivers that were clumsy at best. The complexity of LEDs in the earlier stages were compounded by the lack of available components, which meant one-off application of the technology was out of reach for anyone not up for custom electronics design. (more…)

To set things off on the proper foot – I do not like complexity when it is not necessary. I’ve noted many times that if energy were free and maintenance was not a consideration, the perfect light source is the tungsten halogen lamp. This technology delivers a very attractive white light, is very easy to control, provides optical focus, and is as simple as it can get. The low voltage versions of this technology are equally attractive, accepting that transformers were a horrible thing to tag onto an otherwise neat little light source. I have made hundreds of lights using halogen lamps, mainly 12V versions, starting back in 1985. It was my go-to light source. I still have boxes of transformers and sockets, acquired over years of making lights for myself and others.

Applying LEDs in efficient lighting designs is no more complex than use of any other source, just more productive.

Applying LEDs in efficient lighting designs is no more complex than use of any other source, just more productive, and attractive than CFL or other conventional “efficiency” improving sources.

That said, there is no escaping that energy is an issue, and maintenance is a pain. The cost of operating halogen technologies is simply impossible to bear. This is why we have HID sources with all their ugly liabilities, and the fluorescent lamp.  While I get HID technology as a giant super-power halogen device, it has always been a clumsy, heavy, messy engineering gadget that sets aside the art of lighting for raw lumen energy. Fluorescent lamps have are a source you are forced to live with, in an uninspired, just-get-lumens-in -the-box sort of way. There is very little to love about their scale, lack of focus-ability, ballast hardware, delicate tubes, and ghastly glow. I’ve specified millions of these lamps into existence, wishing every time there was a better way. I never made a single art light using fluorescent lamps, not because itsn’t possible, but because I never liked them enough to give them that part of my time.

The emergence of solid-state lighting, specifically LEDs, hit me in two ways. One, I get the small controllable source I had with 12V halogen. Second, I get the efficiency and raw lumen potential of fluorescent that made it indispensable. Because of this, the last time I made a light using halogen technology was in 2004, and that product was converted to an LED sources in 2006. For my own use, every halogen light I made from 1993 to 2004 still in use around the house, has been converted to LED. Every new fixture made since 2005 has incorporated an LED light source, without exception. I do not use retrofit lamps. I either tear down and rebuild products to utilize LEDs properly, or design them around LEDs in the first place. (more…)