The Emisar D4, made by Hank Wang of Intl-Outdoor, is one of those lights that has created such a stir with its stunning output levels, that if you haven't come across it yet, you will do. Hank has created a light by which others will be judged and at an amazingly low price. Coming in several flavours of LED, with varying maximum output levels, the light on test here is the Neutral White 90CRI Nichia 219CT LED version. Also included with this review sample is the 18350 tube allowing it to be used with 18350 and 16340 cells.

Author's Statement for Transparency and Disclosure
The test sample/s featured in this article have been provided for technical testing and review by the manufacturer. Test samples are retained by the reviewer following publication of the completed review for the purposes of long term testing and product comparisons.

All output figures and test results published in this review are the sole work of the reviewer, and are carried out independently and without bias. Test results are reported as found, with no embellishments or alteration. Though best endeavours are made to maintain the accuracy of test equipment, the accuracy of these results is not guaranteed and is subject to the test equipment functioning correctly.

Taking a more detailed look:

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The beam

Please be careful not to judge tint based on images you see on a computer screen. Unless properly calibrated, the screen itself will change the perceived tint.

The indoor beamshot is intended to give an idea of the beam shape/quality rather than tint. All beamshots are taken using daylight white balance. The woodwork (stairs and skirting) are painted Farrow & Ball "Off-White", and the walls are a light sandy colour called 'String' again by Farrow & Ball. I don't actually have a 'white wall' in the house to use for this, and the wife won't have one!

Modes and User Interface:

From OFF:
1 Click - Turn ON to memorised level.
Press and Hold - Turn ON to minimum and Ramp up.
2 Clicks - Turn ON to Max output.
3 Clicks - Enter Voltage Battery Check (longer flash indicates a 1, short flash indicates a 0. Whole Volts first, then tenths).
From Voltage Battery Check 2 Clicks to enter Temperature Check (longer flash indicates a 1, short flash indicates a 0. Tens of Degrees C first, then Ones)
4 Clicks - Set to use Tactical (Max output) Momentary mode. 4 Clicks to cancel this mode.
6 Clicks - Lockout. 6 Clicks to cancel.
8 Clicks - Beacon Mode
10+ Clicks and hold - Thermal configuration. Hold the button until the D4 is as hot as you want it to get.
When ON press and hold to ramp up or down in output.

Batteries and output:

The Emisar D4 runs on several cell types depending on the battery tube you buy. In this case there is the 18650 tube and the 18350 which also allows a 16340 to be used. Only IMR cells should be used in this high performance light and a 20A output should be considered a minimum.

To measure actual output, I built an integrating sphere. See here for more detail. The sensor registers visible light only (so Infra-Red and Ultra-Violet will not be measured).

Please note, all quoted lumen figures are from a DIY integrating sphere, and according to ANSI standards. Although every effort is made to give as accurate a result as possible, they should be taken as an estimate only. The results can be used to compare outputs in this review and others I have published.

NOTE: the table is not parsing properly in BBcode, so is difficult to read here.

Emisar D4 | I.S. measured | PWM frequency or
using specified cell | ANSI output Lumens | Strobe frequency (Hz)
_______________________________|__________________ __|______________________
18650 Max @ switch on NOT ANSI | 3082 | 16100
18650 IMR Max | 1918 | 16100
18350 Max @ switch on NOT ANSI | 2259 | 16100
18350 IMR Max | 1700 | 16100
16340 Max @ switch on NOT ANSI | 2029 | 16100
16340 IMR Max | 1714 | 16100
Moonlight | <0.1 |

There is parasitic drain. When using 18650, the drain was 22.6uA (15.65 years to drain the cells). On Lockout, the drain was 25uA (14.15 years to drain the cells).

Below is the combined runtime graph for all the types of test carried out. It includes the D4 being run in its factory thermal configuration (45°C), and then the thermal configuration taken to the max. To set the thermal configuration as high as possible, it was set while wearing kelvar gloves (the bezel reached 80°C when setting this). Tests were carried out with fan cooling.

This gallery contains the other versions of the runtime graphs.

Review Summary
Things I like

3000lm+ Max Output.
Flexible UI.
Excellent Thermal regulation.

What doesn't work so well for me

Gets hot very fast due to lightweight construction.
Maximum output drops very quickly.

(Moderators, there is a reciprocal link at the end of every review on Tactical Reviews.)