LED sources

Aputure’s Amaran AL-M9 vs. Sunway Foto’s FL-96

Aputure’s Amaran AL-M9 and Sunway Foto’s FL-96 are very small and handy LED light sources. The Amaran AL-M9 has been relegated to a second place in Aputure’s catalogue by the Amaran AL-MX, but I haven’t bought this newer and three times as expensive version. Both light sources compared here are roughly within the same price range.

I had earlier tested the AL-M9 and noticed that it uses pulse width modulation (PWM) dimming, albeit at high frequency (40 kHz). The FL-96 uses constant current (CC) dimming. Only at extremely fast shutter speeds a difference could be noticeable given the very high frequency used in the AL-M9. Light output is more in the FL-96 compared  to AL-M9, and colour temperature adjustable in the FL-96 while fixed in the AL-M9. However, these differences are at least in part because the FL-96 is a newer design than the AL-M9 which pioneered this type of light source. A comparison of the FL-96 against the new AL-MX would be technically more fair, but unfair with respect to selling price. The oscilloscope traces demonstrate this difference. For details please read my earlier post on LED dimming.

Amaran AL-M9, oscilloscope trace for light to voltage sensor.
Sunway Foto FL-96, oscilloscope trace for light to voltage sensor.

Although intended to be used as fill lights in video taking, these light sources are ideal for macro and close up photography. They do not weight much compared to their light output  with the FL-96 being compact and powerful (132 g, 550-580 lux at 0.9 m, 96 LED,  battery 2500 mAh), the AL-M9 being similar in size and weight but with lower output (140 g, > 80 lux,, 9 LED, battery 1800 mAh) and the AL-MX being significantly heavier (280 g, >200 lux at 1.0 m, 128 LED, battery 1800 mAh). These values are taken from manufacturer’s specifications and the lux values do not seem to be comparable across manufacturers.

The AL-M9 has nine identical LEDs and no possibility of controlling light colour, except for using filters. The FL-96 and AL-MX have each two kinds of LEDs interspersed, half of them emitting warmer and and the other half cooler light. By dimming both groups in opposite directions, intermediate light colours are obtained. The total light output remains fairly constant when adjusting the light colour. The FL-96 has a range from 3000 K to 5500 K settable in steps of 100 K, while dimming is possible down to 5% in steps of 1%. The AL-M9 can be dimmed down to 10% in steps of 10%. The AL-MX can be dimmed down to 20% in steps of 20%, the colour temperature range is from 2800 K to 6500 K but only five fixed set points are available: 2800 K, 4300 K, 5000 K, 5500 K, 6500 K.

Emission spectrum of Sunway Foto FL-96 at full power. Both spectra scales to equal area as for the Amaran AL-M9, below. Dashed line is for CT set to 5500 K, and solid line for CT set to 3000 K. In both cases output power set to maximum.
Emission spectrum of Amaran AL-M9 at full power. Spectrum scale at equal area as for the Sunway Foto FL-96.

According to specifications at full power a fully charged battery lasts for > 1 h, > 1.75 h, and > 1/2 h in the FL-96, AL-M9 and AL-MX respectively. In all three cases the battery is fixed and charged through a USB port. I have tested that the AL-M9 can be used while “charging” connected to a USB power source and will run continuously at full power fed through USB. The FL-96 given that it draws less current through the USB port than it uses to run the LEDs at full power, will not run continuously at full power fed through USB. More importantly, the FL-96 seems to overheat in this situation and trip an over-temperature circuit automatically disengaging battery charging.  The AL-MX which uses a USB-C port and draws 2.5 A through it, can be expected to be able to run continuously on USB power (not tested!).

Comparing EV values, although the FL-96 is about 2.5 times brighter than the AL-M9, this difference is not as large as could be expected from specifications which would imply that the FL-96 is around 5 to 6 times brighter. The AL-MX is described in advertising as the most powerful LED light in its class, which again does not match the specifications, even when taking into consideration the boost mode of the AL-MX. I think the output of the AL-MX in its normal setting could be comparable to that of the FL-96, but higher in boost mode (usable for only 60 s at a time).

Colour temperature and colour rendition index (CRI) are important for good colour reproduction, and of course also when mixing light from different sources. In these respect Sunway Foto specification provides a lot of detail. All three light sources are specified as having CRI > 96 which is very good for LEDs.

Except for the blue peak all spectra are smooth. Testing actual colour temperature (CT) values is rather tricky and disagreement between rated values and the observed white balance cannot be expected to be very reliable without use of a special instrument as camera sensors’ colour channels’ sensitivity to red, green and blue may also deviate from the expected one. The results from an approximate test using an Olympus E-M1 and a slab of white virgin PTFE are good for both light sources at full power. The FL-96 set at 3000 K is balanced in Lightroom exactly at 3000 K and tint -1, set 4000 K it is balanced at 3700 K and tint -3, set at 5000 K it is balanced at 4750 K and tint +6 (camera 4950 K, tint +7), and at 5500 K it is balanced at 5450 K and tint +15 (camera 5500 K, tint +17). The AL-M9 is rated at 5500±200 K and is balanced by Lightroom at 5200 K and tint +19 (camera 5250 K and tint +22). The extremely good match at the extremes of the range of observed vs. rated colour temperature in the case of the FL-96 indicates that LEDs used have very tight colour specifications (colour bin). Intermediate colour temperatures are obtained by coordinated partial dimming of the two types of LEDs. Given the method used to test these values, the not so good match of the AL-M9 is not a demonstration that it is outside the specified range, as measuring errors could have contributed to the differences.

In actual use, both are powerful enough to be used as main or only light source for macro and close up photography, but not comparable to a flash in light output. At distances of 1 m and farther the more powerful FL-96 is preferable. I have two of each, and I normally use them in pairs, one as main light and the other as fill, or both at full power on either side of the object being photographed. I tend to use them at distances from 0.2 to 0.6 m from the object being photographed mounted on Aputure A10 “magic arms”.  Colour rendition is good, noticeably better than with household LED and fluorescent bulbs.

I like very much the design of the FL-96 and its controls. For example having a small OLED screen where the settings are displayed as numbers and also the remaining battery charge expressed as time remaining at the current power setting are very useful. The AL-M9 is simpler and cheaper but it has no indication of the current dimming setting, so the only way of determining the current settings is to cycle through different steps to either maximum or maximum power and count button presses from there. At the time of writing the prices at AliExpress are  55 to 60 € for the FL-96, 40-45 € for the AL-M9 and 130-135 € for the AL-MX. The comparison between FL-96 and AL-M9 leaves no doubt that the FL-96 is a far better piece of equipment for only a very slightly higher price. Whether it is worthwhile paying 2 1/2 times the cost of the FL-96 for the AL-MX cannot be said for sure, but to me it looks very unlikely. Depending on the use case, not being able to use external power with the FL-96, such as a charger or power bank connected through USB while in use, can be a limitation. On the other hand the light output / weight ratio, light output / price ratio, and battery charge duration / light output are excellent for the Sunway Foto FL-96 and better than for either of the two Amaran devices.


All illustrations, text and measurements are of my own authorship, and copyrighted.

(c) 2018 Pedro J. Aphalo

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