There are a handful of flashlights/torches with the flexible Anduril user interface (UI) that are suitable for light painting photography. One of these is the quad LED Noctigon KR4. This review takes a look at how the KR4 performs for light painting photography and general purpose use.
Disclaimer
The Noctigon KR4 was purchased with my own funds. Product links in this review are non-affiliate.
Design and Construction
The Noctigon KR4 is made by Intl Outdoor/Hank Wang, who is well known for producing excellent enthusiast grade flashlights. The KR4 is an 18650 battery format flashlight, with metallic tail e-switch, side clip, quad LEDs, and the flexible but complex Anduril 2 user interface (UI) which has adjustable strobe frequency/speed. The light has a head diameter of 29mm, and length of 98mm. The KR4 is essentially is a tail switch version of the popular side switch Emisar D4V2.
The light has a wide range of LED emitter and LED driver options (more on that later). The TIR optics also have auxiliary RGB LEDs which are just a gimmick, and will need to be disabled for light painting photography. The reviewed light uses 4 Osram CSLPM1.TG (W2) LED emitters chosen for their high lumens/watt ratio and throwy beam. The reviewed light has a 8A Boost driver chosen for efficiency and sustained brightness over maximum lumens.
With a head diameter of 29mm, the KR4 fits in Light Painting Brushes (Universal Connector), and Light Painting Paradise adapters. The KR4 just fits into Luminosify T8 tubes, something which the larger KR1 cannot do. I would assume that the KR4 also just fits into Light Painting Tubes and Light Painting King T8 tubes, but I do not have samples to test. There is no remote pressure switch available.
The tail switch can be unscrewed for battery insertion. Both the head and tail have to be screwed quite tightly for the light to work (using the internal signal tube). The light only accepts unprotected flat top unprotected 18650 batteries. I would recommend the Sony US18650VTC6 3000mAh 30A, Samsung INR18650-30Q 3000mAh 15A, or LG INR18650-HG2. In the Boost driver version, the 3200-3500mAh Panasonic/Sanyo NCR18650GA, Molicell M35A, Samsung INR18650-35E3, EVE INR18650/33V, and LG MJ1 will also work with some extra capacity. As with some other Emisar/Noctigon lights, I find that the springs put too much pressure on the +ve pole of the battery which can cause denting of the pole. Whilst this is superficial only, this should not be occurring.
There is no internal charging, which is likely to be intentional as these lights are aimed at flashlight enthusiasts and not general consumers. Thus you will need to use a dedicated Li-ion battery charger. I am not currently aware of any tail switch Anduril light with internal USB charging that fits light painting connectors, despite my constant nagging to Sofirn for an Anduril version of the SC32!
User Interface
The Noctigon KR4 uses Anduril 2 UI. The main feature for light painting photographers is two strobe modes with adjustable strobe frequency:
Party strobe - 3ms on-time "motion freezing" - 4Hz to 90Hz.
Tactical strobe - 33% on-time - 2.5Hz to 90Hz.
These can be put into momentary mode to allow for fine control of on/off. Any brightness level can also be put into momentary mode, which requires the single stage tail switch to be depressed for the light to be on. Other features include a pulsating bike flash mode, and lightning effect mode. For continuous (non-strobe) output, this light can use ramped brightness or stepped brightness. I recommend using stepped brightness for consistency, which has 7 brightness levels 1/7 to 7/7, plus an even brighter turbo mode. Strobe is fixed at 7/7 brightness level. As anything other than basic use it not entirely intuitive in Anduril, I have written a detailed article on how to use Anduril for light painting photography. Below are the basics:
Enter Advanced UI from Basic UI - 10 clicks, last one hold for 0.5 sec (10H).
On/off (last mode memory for steps 1/7 to 7/7) - 1 click (1C).
Change ramped/stepped - 3 clicks from on (3C).
Change brightness levels (1/7 to 7/7) - hold, release at desired brightness level.
Turbo mode - double click from on from 1/7 to 7/7 (2C).
Enter strobe mode - click, click, hold 0.5s (3H).
Cycle through strobe modes - double click (2C) ...party strobe>tactical strobe>lightning>candle>bike flash>...
Increase strobe frequency/speed - hold, release at desired strobe speed.
Decrease strobe frequency/speed - click, hold, release at desired strobe speed.
Save last used setting into momentary (essential to "save" strobe) - 5 clicks (5C).
Momentary - hold when you need light.
Exit momentary - unscrew tail cap (to break electrical connection).
Additionally, for light painting photography, you will need to disable the auxiliary RGB LEDs. This is done by clicking 7 times (7C) from off (in Advanced UI), which cycles low>high>flashing>off.
I often use Anduril UI flashlights for light painting (as a secondary flashlight to the excellent Light Painting Paradise LightPainter - Ryu's Lightworks flashlight). However, the user interface is complex, and I have had reports from many light painters who struggle to use Anduril UI lights. Persistence with learning to use Anduril UI pays dividends in creativity.
Beam, Output, and Runtime
The Noctigon KR4 has a huge choice of LED emitters. My picks are:
Maximum throw/output - Osram CSLPM1.TG (W2) - reviewed light.
Best for high CRI illumination - Nichia 519A domed (2700k, 3500k, 4500k, and 5700k).
There also some niche options such as E17A Azure colour emitters, and very warm white E17A 1850k. The SST-20 6500k may be a $15 cheaper option for creating light trails than the W2.
The LED driver varies with the chosen emitters, but most default options use a FET driver for maximum brightness which can briefly pull 17A max from a high drain battery. As with most 18650 format flashlights with a brightness of more than 1,500 lumens, this results in very fast brightness step-down (dimming) from approximately 15 seconds due to thermal throttling. In 2022, Noctigon introduced a high efficiency Boost driver option which limits the current to 8A (2A per LED) with lower maximum brightness, allowing for approximately x2 longer time on maximum brightness until step-down, and a higher sustained brightness after that. As I purchased this light for creating light trails in long exposure light painting, and don't want the light to dim during this process, I chose the W2 LED and Boost driver option. This also happens to be the most expensive configuration! As usual for Anduril flashlights, there is a lack of printed product specific instructions and ANSI/NEMA charts.
All testing was with a Samsung INR18650-30Q 3000mAh battery, indoors, 26C ambient temperature, and minimal air flow.
I measured the colour rendering (CRI), colour temperature (CCT), and tint (DUV) with hotspot measurements on 7/7 and 3/7 mode using an Opple Light Master 3 Pro:
7/7 brightness - 68 Ra CRI, 5821k CCT, +0.0056 DUV (slight green tint).
3/7 brightness - 66.1 Ra CRI, 5527k CCT, +0.0086 DUV (slight green tint).
The CRI of the W2 LED is pretty mediocre - fine for use with light painting tools/creating light trails, but I wouldn't use it for night photography illumination. The 519A LEDs are a much better option for high CRI. The CCT of the W2 is what I call coolish white, being slightly warmer than the usual 6500k cool white. There is a slight green tint, but this is only really noticeable on lower brightness levels and side-to-side comparisons with other lights.
The measured brightness @10secs on each mode was:
Turbo - 1,990lm
7/7 - 1,220lm
6/7 - 700lm
5/7 - 361lm
4/7 - 147lm
3/7 - 49lm
2/7 - 20lm (visual estimate).
1/7 - 5lm (visual estimate).
On Turbo mode the light started off at 1,990lm, and rapidly declined after 30secs to 1,192lm at 1 min, from where the brightness gradually reduced to 504lm at 6mins, and 405lm at 9mins. Useful runtime was 220mins. Throw is estimated at approximately 21Kcd/290m.
On 7/7 mode the light started off at 1,220lm, and started to step down after 3 mins, with a gradual decline to 533lm at 5mins, and further step downs to 446lm at 7 mins, and 364lm at 14mins. I would expect that the tactical strobe mode at 7/7 brightness would last at least 9 minutes until the start of brightness step down due to the 33% on-time. Useful runtime was 240mins. Thermal/brightness performance should improve further if a higher temperature setting is set, or in more favourable ambient conditions. However changing thermal calibration settings in Anduril 2 is an exercise in frustration.
I compared the Anduril UI based Noctigon KR4 (7/7 mode) to the Noctigon KR1 (7/7 mode), Lumintop FW1A (7/7 mode), and non-Anduril based UI Sofirn SP31 V2.0 (Turbo mode) in 2 different light painting tools. With a Light Painting Paradise 1m Plexi Tube, there was no significant difference in overall visible light output. With a Luminosify 60cm Choob (T8 Tube), the KR4 was marginally brighter than the FW1A and SP31 V2.0 (the KR1 is too large for T8 tubes). The KR4 will briefly give a bit more of a % brightness boost than the KR1 and FW1A when in Turbo mode.
It should be noted that whilst tactical strobe is at the expected 7/7 mode brightness (other than the very fastest frequency), the 3ms party strobe has a 3 photographic stop hit to brightness due to the short 3ms pulse. This pulse should ideally be slightly longer at around 5ms. As the KR4 has quad emitters it doesn't create good "fairy dust" on party strobe, more like a "fairy splodge". The slowest party mode setting is faster than on my other Anduril lights. The single emitter Noctigon KR1 and Lumintop FW1A are better for "fairy dust".
Conclusion
Positives:
Excellent range of LED options.
Choice of max brightness (FET driver), or max efficiency (Boost driver).
Impressive range of strobe frequency/speeds (at fixed brightness).
Relatively good thermal/brightness performance/size.
Momentary switch can work for any strobe or continuous brightness setting.
Well spaced, stepped brightness levels.
Last mode memory for brightness steps 1-7.
Can be electronically or mechanically locked out.
Fits Light Painting Brushes, Light Painting Paradise, T8 tube, and Lumenman systems.
Side clip included.
Negatives:
Party strobe is relatively dim, and too fast on the slowest frequency - 3ms > 5ms on-time, and 4Hz > 2.5Hz frequency would be better.
Strobe frequency/speed adjustments are ramped - not good for consistency.
No last mode memory for strobe or turbo (you need to use momentary instead).
Anduril 2 UI is too complex for many users.
Lack of printed product specific instructions and ANSI/NEMA charts.
Auxiliary LEDs have to be disabled for light painting.
The tail cap has to be unscrewed to exit momentary mode.
No internal USB charging.
Springs can dent the +ve pole of the battery.
No remote pressure switch option.
For light painting photography - light trails:
With W2 emitters and Boost driver, the Noctigon KR4 is a very good flashlight for creating light trails, with adjustable strobe frequency. It is also bright enough for "blue hour" light painting on Turbo mode. It is most suited to the Light Painting Brushes, Light Painting Paradise, and various T8 tubes systems. If you want decent "fairy dust", you will need to use the single LED emitter Noctigon KR1 or Lumintop FW1A instead. With fixed strobe brightness, the KR4 does not have the creative potential of the Light Painting Paradise LightPainter - Ryu's Lightworks flashlight which has adjustable strobe brightness.
For light painting photography - illumination:
With 95CRI high-CRI Nichia 519A emitter options, and choice of colour temperatures, the KR4 is a good choice for night photography illumination, as are many other lights from Noctigon/Emisar. The Convoy S21D, S21E and S21F are better value for money though, with compatible diffusers and USB-C charging in the E and F models.
For general purpose use:
For flashlight enthusiasts, the range of options is superb, and this can be both a "pocket rocket" light with the FET driver, or a more sensible flashlight with the Boost driver. I would not recommend this light to "muggles" due to lack of USB charging, complex UI, and risk of burning things.
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