When I created Tasca, I had several goals in mind:
- Strong light output – Check – 800 lumens is top of its class
- Smooth wide light pattern – Check – 78 degree beam pattern with no hot spots, no streaks, no rings, >200Fc at 18″
- High color performance – Check >80CRIe standard @4000K, moving to >90CRIe @4000 or 5000K in latest models
- No sparkly LED arrays – Check – single high quality COB array source
- High efficiency – Check – >70lm/W total fixture efficacy
- Tough and Ready – Check – examples have been in operation 24/7/365 in shop environments with zero failures
- ZERO FLICKER – Check – see below
During the development of Tasca, finding a flicker meter was a little tough, so I improvised an oscilloscope and photocell rig that allowed me to see light output modulation. Using this we experimented and tested combinations of LEDs, drivers, and power supplies. I felt the end result was pretty much spot on, as near to the zero flicker from battery operated sources or even daylight as one could get. Yet, until recently, I had not been able to verify this was the case. Enter the UPRtek MF250N flicker meter (review to follow soon). With this, I have finally been able to see how well the Tasca head was performing. I was thrilled with what we found.
Daylight and the DC LED ideal models to set a high bar.
The Tasca Head Result
The results speak for themselves.
I was thrilled with the results. It meant several things. First, these metered results were essentially identical to what we got with our shop made flicker measuring rig. Second, the product itself is simply doing exactly what I intended it to do, which is truly satisfying.
Comparisons for Fun and Perspective
As long as we had the meter out, I figured why not get a few more readings for comparison. The results:
P.S. Notes on the Flicker Argument
I recognize that there is a grand debate about flicker and whether or not it is an issue at all. Most of the argument against setting strict flicker standards are put forth by those who seek to market low cost LED products that exhibit flicker of 120Hz, whether that be AC LED product based or just low end power supply components.
There is no case to be made that flicker is a positive component of lighting, and extensive past industry experience with T12 fluorescent lamps on magnetic ballasts, and HID sources used in commercial application, is what started and fueled the discussion of 120Hz flicker as an issue. Complaints of visible modulation, headache, migraine, etc.. have been studied and found to be corollary to the existence of flicker. Further, studies have proven a connection between flicker below 200Hz having a negative effect on visual performance in schools. While it is true that organizations like NEMA, IES, CIE, and IEEE have yet to come to an agreement as to what defines bad flicker vs. acceptable flicker, this lack of agreement does not indicate there is no issue. In fact, that these organizations have and continue to discuss this issue, against the steady pressure of manufacturers to set it aside, is an indication that there is a very real issue with flicker, that will eventually be resolved – albeit with some compromise included to placate manufacturers involved in standards proceedings. As a member of the IEEE 1789 committee on the topic of the risks of flicker, I can attest to the depth in which this topic has been investigated and discussed, and bear witness to the hundreds of papers written on it and its effects on vision and human physiology.
In my own opinion and recommendations to others, I ask one question – If there are sources and products available that exhibit no flicker, or flicker of such character as to not be an issue (such as T8 and T5 fluorescent on electronic ballasts, and quality LED driven products), what is the reasoning for continuing to accept any products that flicker in the zone of 100Hz to 200Hz, with a flicker amplitude >0.3 (minimal modulation depth) at all? Any level that exceeds, approaches or shares flicker characteristics with the T12 fluorescent lamp on magnetic ballasts, in my opinion, should be considered unacceptable for any use, regardless of arguments over cost saving. This includes any continued use of magnetic ballasted HID sources for interior illumination and AC connected LEDs (with no flicker mitigation) – as these are all far worse than the T12 lamp.
While in ambient lighting, a weak case might be made that flicker may be of small consequence – I propose that in task illumination, where visual acuity is critical, focus is the goal, and high illuminance and task demands increase the risk of stress, there is no rational case to be made to accept flicker of any level. For this reason, I have focused my attention and effort on creating lighting systems (and sources for components) that present either no flicker at all, or characteristics, such as high frequency operation (>2,000Hz), very low modulation depth (amplitude of <0.3%), low flicker index (<0.05), at all light level settings or dim states. I believe these to be reasonable and attainable standards, and have found no reason to accept poorer performance.