Links and Handouts for the LED Specifier Summit Meter Presentation

Posted: November 14, 2016 in General Commentary, Light Meters, Uncategorized

thumb-meterFor those who attend my presentation on Metering and Meter use at the LED Specifier Summit this Tuesday (9:00AM) here is the related reference information and a copy of handouts for the presentation. Let me know what you think and post your comments or questions here. If you have any questions or wish to discuss this presentation or have a metering issue you’d like some help with, let me know.

Here is a copy of the presentation handout here: LED Spec Summit KLW Meter Presentation

The following are a summary of the links to the meter files content referred to in the presentation:

Meter Review

Flicker Wheel

Flicker Meter Review

LQC Classification Article

LQC Workbook

Color Viewer


  1. Mike Turner says:

    Hello Kevin,

    I attended your presentation at Navy Pier last November and came away thinking (other than how I thought your presentation was quite good – sorry for the shameless flattery) that I need to get my light meter calibrated. I’m finally getting around to it now, but before I did anything I thought maybe you could point me in the right direction.

    Our office uses the Extech Instruments 401025 light meter for general lighting; we don’t need it for anything more than that. We’ve had it for at least 5 years, and it has never been calibrated to my knowledge. My question to you is: is it worth it to get this thing calibrated (and how and at what cost… would you recommend Transcat?) or are we better off purchasing a new one so that we can get better LED readings, such as the Extech LT45? Or would you recommend getting the Amprobe LM-200LED?


    • kwillmorth says:

      Okay, to start, you will not find having low cost meters calibrated a good experience. Calibration will cost more than the meter. Calibration for most illuminance only meters will run ~$400, so there it doesn’t make a ton of sense to bother for a $150 meter.

      As a point of reference, meters are roughly calibrated at the factory. If you want one that will pass muster from day one, even a new meter needs to be calibrated to a reference. That means a $150 meter actually costs $550, to cover initial calibration.

      For general illumination use, the single best bang-for-the-buck meter today is the ILT (International Lighting Technologies) ILT350: ( It is inexpensive ($1099), will last for a lifetime, can be calibrated by ILT at a nominal cost, provides light readings, CCT, CRI, and can have its software updated in the future if there is something new you want to add. This meter is equal to meters costing 3X the price, with poorer displays and less features. For example the venerable Minolta T-10A is a battleship light meter, but all it does is read Fc or Lux, and costs more than the ILT. The ILT350 is essentially the only meter you need. The meter also is connectable to a PC to download up to 100 stored readings

      If you should want more data points, like the TM30 values, etc… that’s when you get into the others I covered in my meter reviews elsewhere on this blog.

      Okay, so I know there are those who don’t want to spend that much. With a budget of $200 or less, there are several acceptable meters. I’ve found the Amprobe LM-200LED a good little meter. The Extech LT45 reads colors, but not CCT, so is probably not what you are looking for. The LT40 will get the job done. The better choice from Extech is the Easy View:

      Keep in mind that any meter that costs less than $500 is essentially a Bik lighter. Use it for a few years (5 years of moderate use is about it), and toss it for a new one. The cost of calibrating the ILT is less.

      The trick for knowing when you need a re-calibration is to set up a reference of some sort you can store away. Use a length of 1.5″ x 12″L PVC pipe and an LED retrofit lamp mounted in an old table lamp base. Put the pipe over the bulb and take a measurement. Write the reading on the side of the pipe, then store it and the lamp in a safe place. Every year, repeat the test. If the reading is the same (+/- 10%) you are good to go. If the reading is off by more than 10% you need to send the meter in for calibration.

      Good luck.

      • Mike Turner says:

        Many thanks for the recommendations. I think we’ll go for the replace every five years option for now.

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