Introduction
In 2018 I wrote a post comparing the Sunwayfoto Fill Light FL96 and the Aputure Amaran AL-M9 mini LED light. In 2025 they are both still available new. Meanwhile Sunwayfoto has released a few variations on the original model, the FL96 C with batteries with increased capacity and faster charging through USB-C, and in the case of the FL120, slightly higher light output and power-bank function.
More recently, I bought an Elgato Key Light Mini, and decided to run a new and more thorough comparison between these the three commercial LED light sources that I own. In part because I am now able to compute CRI and CCT values from the measured spectra and because the Elgato Key Light Mini has much improved diffusion. Thus, in 2022 I revised what I had written in 2018. After the conversion to Quarto, a few rough edges remained. In 2025 I did some edits and added photographs illustrating the banding artefacts visible in images when the Amaran AM-L9 is used.
I bought the LED lights tested here several years ago. While the SunwayFoto FL-96 and ElGato Key Light Mini are still available new for purchase in 2025, it is impossible for me determine without buying new ones if their electronic circuits or the LED types used remain exactly the same as in those I own. They could have been upgraded, or even downgraded, in the meantime. Production of the Amaran AM-L9 seems to have been discontinued. Keep this in mind if you make use the information in this note.
This article is based on a single unit of each LED light type. I do have two FL-96 and two AL-M9, and there seems not to be any big differences within these pairs. However, the two lighths in each pair were bought at the same, and are most likely from the same production batch. I have a single Key Light Mini.
The three LED lamps differ in size and weight, however their maximum light output and battery capacity is not proportional to their size or weight.
| Feature | AL-M9 | FL-96 | Key Light Mini |
| Power (W) | 3 (?) | 8 | 15 |
|
Lumens |
180 (?) | 600 | 800 |
|
Lux at 0.6 m |
(300) | 1120 | no spec. |
| Diffuser (cm2) | 34 | 50 | 100 |
|
Illumination |
behind diffuser | behind diffuser | diffuser edge |
|
Weight (g) |
70 | 132 | 300 |
| Battery (mAh) | 1800 | 2800 | 4000 |
| Control | Buttons | Wheel | Buttons + Wifi |
| Display | No | OLED | No |
|
External power |
charge | charge | charge + use |
Light output
I measured spectral irradiance at 160 mm distance from the three LED lights in a darkened room. I repeated the measurement on the Key Light Mini as it turn out to be way out specifications. I tested over the whole range of dimming and of CCT values of each light, but not every possible combination. Of special interest is the change in light output vs. CCT because the variation in CCT is implemented by mixing light from two types of LEDs.
We first look at the output expressed as energy irradiance, which is most likely to remain constant with CCT change if the sum of the electrical power driving both types of LEDs remains constant. The AL-M9 has nine identical LEDs and is rated at a CCT of 5500 K, and serves as reference. The FL-96 and the Key Light Mini each is based on LEDs with emission at two different CCT values. In the FL-96 the change in CCT is implemented so that adjusting CCT does not change significantly the total light output, while in the Key Light Mini, full output is obtained only at CCT values close to 4000K and at extreme values of CCT the light output is only only half the maximum. The FL-96 is far superior in this respect as its full rated power is available at all CCT settings. In the FL-96 adjustment of dimming and CCT are independent of each other (orthogonal controls) which is also easier and more intuitive to use.
Surprisingly, the much smaller FL96 outperformed the Key Light Mini in light output at the very short measurement distance 16 cm I used for most tests. I expected that farther away, given the larger emitting area, the Elgato LED light would catchup with the Sunwayfoto, but a measurement at 64 cm showed the FL-96 continued outperforming the Key Light Mini. This is surprising as the Key Light Mini according to specifications emits 33% more light than the FL-96, 800 lumen vs. 600 lumen.
Output from LED lights is normally described in specifications in lumens and lux, which are technical quantities designed to approximate the spectral response of human daytime vision. The spectral response of camera sensors is different, and to an extent dependent on the camera model. We can convert the energy irradiances in the figure above into illuminance expressed in lux (= lumen × m-2). Given that the eye is most sensitive to green light, the shape of the curves very slightly changes (not shown).
At 0.6 m with both lights set at 4000 K and 100% output, I measured an illuminance of 825 lx for the FL-96 and 730 lx for the Key Light Mini, the value for the FL-96 is about 13% higher. The rated illuminance output of the FL-96 is approx.1100 lx at this distance (from a total rated output of 600 lumens). For the Key Light Mini I have not found any illuminance specifications, while the luminance rating is 800 lumens, or 33% higher than for the FL-96. I measured the output in surroundings with low reflectivity and the FL-96 has been in use for some years. The Key Light Mini has better diffusion and larger emissive surface, thus a broader light beam that may explain the lower illuminance. If we look at the relative change in illuminance with measured CCT, then it is obvious that the FL-96 is much more versatile if one needs illumination at different colour temperatures, in spite of its narrower nominal CCT adjustment range. At 5500 K or 3000 K, illuminance obtained with the FL-96 is more than twice as strong as with the Key Light Mini.
Next we explore how well the nominal CCT reported by the LED light sources matches the CCT computed from the measured spectra. A LED lamp with nominal and measured CCT in agreement is described by the black dashed line. We see that the nominally much broader range of colour temperatures in the specifications of the Elgato LED lamp (2900 K to 7000K) compared to the FL-96 (3000 K to 5500 K) does not match the measured values, approaching those of the Sunwayfoto LED light which performs very close to the reported nominal values.
Specifications for CCT in the case of the FL-96 are plus or minus 200 K. For the Key Light Mini Elgato makes no promises other than a CCT range of 2900 K to 7000 K. It is important to keep in mind that unless the light spectrum allows perfect colour reproduction, the CCT values estimated using different approaches cannot be expected to agree. This is clearly the case for the automatic white balance of cameras compared to computed from an spectrum with high wavelength resolution. Given the large difference in CCT, I contacted Elgato support. The initial answer was fast and once the problem was confirmed the support staff consulted the technical staff. The last information receive was that the question had been passed along to the manufacturer. I never received any further information.
In the ElGato Mini Key Light Mini diffusion is much better than in the other two LED lights. This is achieved by a larger size and diffusion by illumination from the edges of the panel rather than from behing it. How much difference this makes depends on the situation, e.g., how close the lamps are to the subject. Another advantage is the remote control through Wifi. This is indeed very handy, but is marred, because as we saw above by settings do not agree with the real CCT values. I also find rather problematic that the light output decreases drastically when changing the CCT setting away from intermediate values.
Dimming
The three light sources differ in how dimming is implemented. Two approaches in common use are pulse width modulation (PWM) and constant current (CC). In PWM dimming the LEDs are rapidly swithced on and off, without altering the output during the time when they are on. In CC dimming the current through the LEDs is decreased to decrease the light output but maintained constant in time. In PWM the light output flickers with CC it does not. I discuss these approaches to dimming in the context of digital photography in the page PWM dimming and digital photography at this site.
Dimming of the Amaran AL-M9 is done by pulsing (PWM at 40 kHz) while that in the Sunwayfoto FL96 is done by constant current (CC). The dimming in the Elgato Key Light Mini is done by PWM at 146 kHz. The dimming of the Amaran AL-M9 is done in 10 steps, while in the other two LED lights the setting is described as a percentage with a resolution of 1% for the setting. The fastest light sensor I have according to specifications has typical rise and fall times of \(2\,\mu s\), making it impossible to observe the real shape of the light pulses at these high frequencies, while measuring the frequency is possible.
In principle constant current dimming is preferable to PWM, as with PWM light output pulses between maximum output and off, with varying duty cycle, rather than being constant in time. When the frequency is very high, the effect is unlikely to be reflected in the images we take. In the case of 40 kHz, one might start seeing inconsistent exposure on successive image frames with shutter speeds close to the maximum available in digital cameras, around 1/16000 of a second. PWM at 146 kHz is unlikely to affect any normal photographic camera. Many modern digital cameras can scan the light to determine the frequency and automatically adjust the shutter speed and metering system to ensure consistent exposure from frame to frame. Let’s not forget that illumination at many home and businesses flickers at 100 Hz or 120 Hz, because of the frequency of AC mains power. However, only in the case of LEDs the pulsing is on/off. With incandescent lamps and fluorescent tubes the fluctuation is between two levels of brightness. Most problematic is when different light sources, possibly with different emission spectra, are pulsed at different frequencies. This can result in very clear colour banding in photographs, especially when using electronic shutter in cameras in which rows of pixels in the sensor are read sequentially.
[2025-03-06] The Sunwayfoto FL96 LED light emits constant ligth and as expected no banding is apparent even at a shutter speed of 1/32000 s. The frequency of the light pulses in the ElGato Mini light seems also fast enough to avoid banding at 1/32000 s and slower shutter speeds. With the Amaran AL-M9 banding is evident at 1/32000 (Figure 4). Measurement with an oscilloscope revealed that at full power this light source has only a duty cycle close to 85%, rather than 100%. Thus with the Amaran AL-M9, banding at 1/32000 s cannot be avoided by using it at full power (Figure 4 (b)). At half power, banding is very evident at 1/32000 s and becomes (Figure 4 (d)) and evident all the way down from to about 1/2000 s, although it becomes progresively fainter as the shutter speed decreases. The flicker scan function in the camera sets the shutter speed to 1/310 s, fully avoiding banding (Figure 4 (f)). Banding is less noticeable with older digital cameras with longer read-out times than with the OM-1 because with them the bands are more numerous and narrower.
In the FL-96 the real dimming is less than the nominal one, while in the Elgato LED light, the real and nominal dimming match very well. It is remarkable that the Elgato LED light can be dimmed down stably to less than 5%.
All three LED lamps are described as having very high values for the colour reproduction index (CRI). The figure shows how the measured CRI varies with measured CCT. All light perform reasonably well with the FL-96 and the AL-M9 overall performing better than specified and the Key Light Mini, tends to perform below specifications, with specifications that are lower than for the other two LED lamps. A difference at 5500 K between 97.5 and 93 may for subjects of specific colours and cameras.
Probably in actual use, one of the most critical aspects of performance is that dimming should not affect the colour temperature. This is likely to be most difficult to achieve at intermediate CCT values when the light is coming from two different types of LEDs. I tested this at 4000 K and as shown in the plot below, there is an important change in colour temperature when light output is strongly dimmed.
The change in the spectrum with dimming also leads to a small decrease in CRI.
An important question is if the light sources matched or not the specifications given by the manufacturers. Here is where I was most surprised. While the AL-M9 and the FL-96 were very close in CCT to the setting at 5500 K (at the “cool” end), the Key Light Mini was more than 1000 K warmer than settings (less than 6000 K at the 7000 K setting). This is a huge difference! At the “warm” end differences between settings and actual performance both for the Sunwayfoto and Elgato were rather similar in magnitude and smaller. For the FL-96 the difference between CCT measurement and settings was largest at the middle of the CCT range.
Conclusion
Did I return the Key Light Mini because it does not fulfil the specifications? No. Would I have bought it, knowing what I know now. Yes, as alternatives do not have built-in batteries. In fact I have been using both my two Sunwayfoto FL96 LED lights and my ElGato Key Light Mini frequently since I bought them, as suit different situations
With the ElGato Key Light Mini I mostly use 4000 K, the CCT at which light output is reasonably strong. What I find most annoying is the mismatch between the settings in the App and the actual CCT as I makes matching the CCT of other light sources cumbersome. The actual range of CCT even if not as broad as promised is enough for me. For many uses it is the best of the three lights, because its large surface and better diffusion makes it much more comfortable on the eyes of the subject. When illuminating shiny objects at close range it is also better than the FL-96, with which reflections can produce multiple bright spots, which look very unnatural.
- The ElGato Key Light Mini better than the other two LED lights as main light.
- The ElGato Key Light Mini is also an excellent light source for digitizing colour slides and negatives with a camera.
- The FL-96 is most useful as a fill light (and doubles as a pocket-sized very bright flashlight).
- The AM-L9 is small and light weight, but in practice it is the least useful of the three LED lights.
I have not used the AM-L9 LED lights after buying the two FL-96. There is room for improvement in the Key Light Mini, and hopefully an upgraded version will be produced in the future.
However, I do find it worrying that specifications are not fulfilled by a product from a well known brand. This raises in my mind the question of how accurate are CCT ratings of LED lights in general, including those from other brands rated at wider ranges, such as 3000 K to 9000 K.
[2025-03-07] My Sunwayfoto FL-96 LED fill lights have been is use for nearly seven years, without a single problem. Their batteries have still good capacity and the hard anodization of the aluminium body still looks like new. I have found and additional use for the