There are a handful of flashlights/torches with the flexible Anduril 2 user interface (UI) that are suitable for light painting photography. One of these is the Noctigon KR4 with quad LEDs. This review takes a look at how the KR4 performs for light painting photography and general purpose use, configured with Nichia 519A high-CRI LEDs and a Boost driver.
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 Noctigon KR4 has a huge choice of LED emitters, which are often changing. My picks at the time of writing are:
Maximum throw/output - Luminus SFT-25R
Best for floody high CRI illumination - Nichia 519A domed (2700k, 3500k, 4500k, and 5700k).
These are both US$77 with Boost driver, and US$65 without, though there are often discounts available. There are also some niche options such as E17A Azure colour emitters, and very warm white E17A 1850k. It may be possible to order 'off-menu' (email before ordering) colour LEDs including XP-E Red, Green, Yellow, Pink, Cyan, and Purple.
The TIR optics have auxiliary RGB LEDs which are just a gimmick, and will need to be disabled for light painting photography. This review looks at the KR4 with quad Nichia 519A LED emitters which have high colour rendering index (CRI). The reviewed light has a 8A Boost driver chosen for high efficiency and sustained brightness over maximum lumens. Some Emisar/Noctigon models have the new Lume X1 driver, however at the time of writing it wasn't available as an option on the KR4.
With a head diameter of 29mm, then for light painting photographers, the KR4 fits in the Light Painting Brushes (Universal Connector), and Light Painting Paradise (cone) adapters. The KR4 also squeezed into the prototype Light Painting Paradise Ryu's V2 "All in one" adapter, making it a useful cheaper companion light (note: the final version of this connector has not been tested for compatibility). 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, but the tail switch can be used in momentary and tactical modes. The light has excellent ergonomics. Due to the light being quite short I only have to use one hand to hold the light painting adapter with my thumb on the momentary switch.
The tail switch can be unscrewed for battery insertion. Both the head and tail have to be screwed very tightly for the light to work (using the internal signal tube). The light only accepts unprotected flat top unprotected 18650 batteries. For use with the standard linear FET driver, I would recommend the Sony US18650VTC6 3000mAh, Samsung INR18650-30Q 3000mAh, LG INR18650-HG2, or Molicell P28A 2800mAh. For the Boost driver version, I would recommend the higher capacity Panasonic/Sanyo NCR18650GA, Molicell M35A, Samsung INR18650-35E3, EVE INR18650/33V, LG MJ1, Vapcell F38 or N40. 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. As the light uses an inner signal tube, it is critical that both the head and tail are fully screwed on for the light to work after a battery change.
There is no internal charging, which is likely to be intentional as these lights are aimed at flashlight enthusiasts and not general consumers. You will need to use a dedicated Li-ion battery charger. The only tail switch Anduril light I'm aware of with USB charging (in battery) is the Wurkkos TS10 Max, which I hope to review in early 2025.
Accessories included with the light included the side clip (installed), a lanyard, and spare O-rings.
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 80Hz.
These, or any continuous brightness mode, can be put into momentary mode to allow for fine control of on/off when the single stage tail switch is depressed/released. 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). You should only need to do this once unless you do a factory reset or click too much!
On/Off (last mode memory for steps 1/7 to 7/7) - 1 click (1C).
Toggle 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 (2C).
Enter strobe mode - click, click, hold 0.5s (3H) from off.
Cycle through strobe modes - double click (2C) ...party strobe>tactical strobe>police 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 only when you need light.
Exit momentary - unscrew and re-screw tail cap (to break the 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 with each 7C.
There is a fairly new Tactical mode, entered or exited with 6 clicks (6C). It is then possible to configure 3 different settings (including strobe) to be accessed by 1H, 2H, or 3H. (See diagram). This is rather complex to configure, so only really useful if you need to access more than one setting with momentary mode. The default settings are also not optimal (unlike the Wurkkos TS10 SG).
There are two new(ish) features which are enabled by default, but can be turned off in configuration. These are the "soft start" functionality, which creates a short fade during on/off/brightness change and battery check display using the RGB auxiliary lights when the light is turned off. As I only use the KR4 for light painting in momentary mode, these don't affect my workflow, but I would prefer them to be disabled by default.
I often use Anduril UI flashlights for light painting (as a secondary flashlight to the excellent Light Painting Paradise LightPainter - Ryu's Lightworks V2 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.
It should be noted that there are many versions of Anduril 2 in use. The tested light had a recent 2024 version, but some other Anduril lights may use older versions with different functionality and default configuration.
Beam, Output, and Runtime
The Noctigon KR4 has a huge choice of LED emitters. This review tested the Nichia 519A domed 5700K. These LEDs are in a quad TIR reflector, and result in a floody beam profile. Due to the floody beam profile, there is much less beam artifact than the previously tested W2 version.
The LED driver varies with the chosen emitters in the KR4, but most default options use a linear FET driver for maximum brightness which can briefly pull more than 15A from a high drain 18650 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) 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 a much more gradual driver step-down, and a higher sustained brightness. 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 Boost driver option. As usual for lights from Noctigon/Emisar which have a large range of LED options, there is a lack of printed product specific instructions and ANSI/NEMA charts.
All testing was performed with a Samsung INR18650-30Q 3000mAh battery, indoors, 27C ambient temperature, and minimal air flow.
I measured the colour temperature (CCT), colour rendering (CRI), and tint (DUV) with hotspot measurements using an Opple Light Master 3 Pro:
Turbo - CCT 5480K, CRI 98.1 Ra, Tint -0.0047 DUV.
7/7 - CCT 5405K, CRI 98.5 Ra, Tint -0.0045 DUV.
5/7 - CCT 5245K, CRI 98.9 Ra, Tint -0.0042 DUV.
3/7 - CCT 5159, CRI 99 Ra, Tint -0.0042 DUV.
2/7 (unable to measure 1/7) - CCT 5058K, CRI 98 Ra CRI, Tint -0.0047 DUV .
The CCT is slightly lower than specified; and decreases with lower brightness. The CRI is exceptional at all brightness level, and will render colours, particularly reds and browns, much better than standard 70 CRI flashlights. This is useful for light painting illumination, and light painting portraits (for skin tones). The tint is also consistently neutral at all brightness levels, with a very slight magenta tint.
The measured brightness @10secs on each mode, using a Samsung 30Q 3000mAh 18650 battery was:
Turbo - 2447lm
7/7 - 1478lm
6/7 - 802lm
5/7 - 380lm
4/7 - 151lm
3/7 - 47lm
2/7 - 10lm
1/7 - 1.5lm
On Turbo mode the light started off at 2447lm, with step-down starting from 30secs. This step down is gradual, 1889lm at 1min, 1063lm at 5mins, 662lm at 10mins, and stabilising at 557lm from 15mins. There was a major step-down at 1hr24mins, and useable brightness until it dropped to 1/7 (moonlight) level at 1hr44mins. This was tested with default temperature control settings, indoors in 28C heat and no wind. In most real world conditions I would expect higher sustained brightness. For the light's size, 557 lumens is pretty impressive sustained brightness.
Tactical strobe appears to run on Turbo brightness (other than the very fastest frequency). I'm pretty sure some previous Anduril 2 versions were at 7/7 brightness? The 3ms party strobe has a 3 photographic stop hit to brightness due to the short 3ms pulse. As the KR4 has quad emitters it doesn't create good "fairy dust" effects on party strobe, more like a "fairy splodge". The single emitter Noctigon KR1 and Light Painting Paradise Ryu's V2 are better for "fairy dust".
Throw was tested against the KR4 with W2/Boost configuration:
519A Boost Turbo - 6,487cd (161m)
519A Boost 7/7 - 3,918cd (125m)
W2 Boost Turbo - 25,533cd (320m)
W2 Boost 7/7 - 15,871cd (252m)
Note: My Opple Lightmaster 3 Pro tends to over-estimate lux readings by 25%.
The throw was less than expected (both the single 519A emitter Convoy S2+ and S21E have more throw), but this is a "flooder" and does what it says on the tin. The W2 version, now superseded by the SFT-25R version has much more throw, but low CRI and a slight green tint. The SST-20 2700K and 4000K versions are high-CRI throwy options, but I'm not a fan of the increasingly green tint at lower brightness levels with SST-20s. The de-domed 519A will also provide more throw, but with a magenta tint.
Conclusion
Positives:
Excellent range of LED options including "floody" high-CRI, or "throwy" low-CRI.
Choice of Boost (efficient, high sustained brightness) or standard linear FET driver (max brightness).
Excellent CRI and neutral tint in 519A version.
Adjustable strobe frequency (at fixed brightness).
Excellent sustained brightness / size.
Momentary or tactical modes 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.
Excellent light painting system compatibility - Light Painting Brushes, Light Painting Paradise, and some T8 tubes.
Side clip included.
Negatives:
Strobe frequency/speed adjustments are ramped - not good for consistency.
No last mode memory for strobe or turbo (you need to use momentary or tactical modes 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.
I'd prefer some Anduril 2 features to be disabled by default.
The tail cap has to be unscrewed to exit momentary mode (tactical mode is now an alternative).
No internal USB charging.
Springs can dent the +ve pole of the battery.
No remote pressure switch option.
For general purpose use:
The range of LED options is superb, with both throwy options such as the SFT-25R or floody high-CRI options such as the 519A. The Noctigon KR4 can be both a "pocket rocket" light with the FET driver, or a slightly more sensible compact flashlight with the Boost driver. Noctigon and Emisar lights are aimed at flashlight enthusiasts. I would not recommend these lights to "muggles" due to lack of USB charging, complex UI, and risk of burning holes in things.
For light painting photography - light trails and illumination:
With high-CRI Nichia 519A emitters that can render skin tones well, Boost driver, and adjustable strobe frequency, the Noctigon KR4 is a useful flashlight for light painting portraits. If you just want max lumens and throw for use with saber like tools, choose the low-CRI SFT-25R option with Boost driver instead. The 519A's high-CRI output, neutral tint, and range of CCT options are also very useful for the illumination side of light painting. With fixed strobe brightness, the KR4 does not have the creative potential of the Light Painting Paradise LightPainter - Ryu's Lightworks V2 flashlight which has adjustable strobe brightness and frequency. However, the KR4 is still my favourite flashlight for light painting, that hasn't been designed specifically for light painting. The Anduril 2 UI requires tech savvy users.
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