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  • Stephen Knight

Flashlight Review: Convoy M21H (8A Getian GT Colour LED)

Updated: Feb 3

Convoy is one of my favourite flashlight/torch manufacturers, as they sell flashlights with new and interesting LEDs that are often not available from other manufacturers. Most flashlights with colour (red, green, or blue) LEDs are limited in current to 1 to 3 Amps. The Convoy M21H, with Getian GT colour LEDs uses a whopping 8A current.


Disclaimer


The Convoy M21H was purchased with my own funds. Product links in this review are non-affiliate links. This review is written from the perspective of a light painting/night photographer and flashlight enthusiast.


Convoy M21H Flashlight
Convoy M21H Flashlight

Design and Construction


Convoy offer a huge range of lights with coloured LEDs. The Osram CSLNM1 red, blue, full spectrum green, and full spectrum yellow-orange are available as options in many lights including the T5, S2+, C8+, and Z1. The new (presumably 7070 format) Getian GT 3V 8A red, green, and blue LEDs are available in the M21H (reviewed here), C8+, M21A, Z1, and L21B. The SST-20-DR deep red and CSLPM1.F1 full spectrum green are also available in a selection of lights.


The Convoy M21H is a medium sized flashlight that uses 21700 Li-ion batteries, and has a 40mm head size. The length is 130.8mm, body tube 27mm width, and the weight is 132g. There is a single side e-switch. The light was priced at US$28 at the time of writing. The strong cardboard packaging only included the flashlight and a lanyard. There was no side clip or spare O-rings included. There are no instructions, but these are on Convoy's product page.


The Convoy S21H uses a single Getian colour LED available in either red, green, or blue. This review is of the green LED version. The emitter is placed in a 12 degree TIR optic, for a relatively throwy beam profile.


The Convoy M21H requires a 21700 Li-ion battery. This is not included. Check out my Battery and Charger Buying Guide for recommendations. Testing was performed with a Samsung 50E 5000mAh 21700 battery. The battery tube has springs at both ends of the battery tube. Charging is claimed to be at 2A, and the 5000mAh battery took 3 hours 5 minutes to fully charge. Charging terminated at 4.21V which is acceptable.


The 40mm head size of the M21H is too large to connect to commercial light painting tools, and thus the M21H is more suitable for the illumination side of light painting and night photography, rather than creating light trails. The M21H does have a compatible diffuser, which creates omni-directional light, like a light bulb. The M21H can also be tripod mounted using a clamp such as Small Rig Super Clamp.


Convoy M21H Packaging
Convoy M21H Packaging

Convoy M21H Side e-Switch
Convoy M21H Side e-Switch

Convoy M21H USB-C Charging Port
Convoy M21H USB-C Charging Port

Convoy M21H Diffuser
Convoy M21H Diffuser

Size Comparison L to R - Convoy S2+, Skilhunt / ESKTE MiX-7, Convoy M21H
Size Comparison L to R - Convoy S2+, Skilhunt / ESKTE MiX-7, Convoy M21H

User Interface


The Convoy M21H uses Convoy's easy to use side e-switch user interface. This is the same as found on many of the M21 series lights and popular S21E. From the Convoy website:


1.click the button ——> flashlight is turned on with last brightness ——> press the button,brightness ramping up ——> release and press the button again,brightness ramping down

2.flashlight off, press the button ——> moonlight mode (0.2%) [This brightness will not be remembered]

3.flashlight on or off, 2-click the button ——> turbo 100%

4.flashlight off,3-click the button ——> strobe

5.flashlight off,4-click the button ——> tactical mode, only 100% ,4-click the button again to quit tactical mode.

6.flashlight off,5-click the button ——> voltage detection (* means "flash" , *** pause ******* means 3.7V, )

7.flashlight off,6-click the button ——> normal ramping mode switch to 4modes 1%-10%-40%-100%

8.flashlight off,10-click the button ——> Lock mode,The flashlight will flash once under any operation, which means the flashlight is locked.10-click the button again to quit lock mode. Please note that this is the only way to unlock.

The flashlight has low voltage protection and temperature control protection.


I find this user interface easy to use and remember, yet it has a lot of useful features such as ability to switch between stepped/ramping brightness, battery check, tactical mode, and lock out mode. The strobe is constant frequency. The light can also be locked out mechanically be slightly unscrewing the tail cap. As with previous versions of the Convoy e-switch user interface, the ramping could be slower at lower brightness levels.


Beam, Output, and Runtime


The Convoy M21H is available with a range of LED emitter versions. This review is using the high output 3V 8A Getian colour LEDs, available in either monochromatic Red 620-630nm, Green 520-530nm, or Blue 450-460nm. The Green LED version was tested. The LED is placed in a TIR optic, with 12 degree hotspot beam angle. This created a relatively throwy beam, with a fairly dim but wide spill beam. This beam profile may be useful for hunting, or medium to long range illumination. I would like to see a more floody TIR optic choice to be added to the product listing - I'm not sure if Convoy's range of 35mm optics designed for the GT-FC40 and XHP.70.x are suitable for this LED.


Testing disclaimer - I tested both relative lumen output, and peak beam intensity. When testing with white light output, my results are usually within +/-10% accuracy of test results using expensive integrated spheres and light meters. However, I would debate the accuracy of my testing equipment when testing monochromatic light. For example differences in the primary green wavelength used by different lights may result in inaccuracies in testing. Despite this, these results did correlate with visual comparisons.


Relative brightness/lumen output for green LED output, tested using the ceiling bounce method with Light Meter App/Google Pixel 6.

  • Convoy M21H 100% - 100%

  • Convoy M21H 40% - 61%

  • Convoy M21H 10% - 28%

  • Convoy M21H 1% - 4%

  • Convoy S2+ CSLNM1.F1 100% - 93% (*note: this is full spectrum green and comparison may be innacurate)

  • Skilhunt MiX-7 100% - 38.4%

  • Olight Marauder Mini 100% - 29%

  • LED Lenser P7QC 100% - 18%

  • Weeylite RB9 Panel Light 100% (H 120, S 100%) - 125%


Relative peak beam intensity or illuminance, measured with a Opple Light Master 3 Pro.

  • Convoy M21H 100% - 100%

  • Convoy M21H 40% - 58%

  • Convoy M21H 10% - 10%

  • Convoy M21H 1% - 1%

  • Convoy S2+ CSLNM1.F1 100% - 213% (*note: this is full spectrum green and comparison may be innacurate)

  • Skilhunt MiX-7 100% - 11.1%

  • Olight Marauder Mini 100% - 6.24%

  • LED Lenser P7QC 100% - <1%

  • Weeylite RB9 Panel Light 100%, 120degrees, 100% sat - <1%


On 100% "Turbo" mode, the light stayed above 92% until 140 seconds, followed by a gradual stepdown over the next minute to 57% output. Output then stayed relatively stable until it dropped to 1% mode at 124 minutes. Low battery warning (red flashing button) started at 132 minutes. As is often the case with Convoy flashlights, the light runs very hot, but within safety limits for Li-ion batteries.


As the brightness level lowers, there is a change in hue towards yellow. This is most notable on 1% mode. I have not noticed this before with coloured LEDs, but upon re-testing other lights with green LEDs, it is perfectly normal.


Convoy M21H TIR Lens
Convoy M21H TIR Lens

Getian GT Colour LED
Getian GT Colour LED

Convoy M21H Getian GT Green Beam Profile
Convoy M21H Getian GT Green Beam Profile

Not surprisingly, the Convoy M21H with Getian GT 8A green LED, has higher brightness/lumens and peak beam intensity than all other (single battery) monochromatic green lights I've tested by quite a large margin. It is possible that the Emisar D4K or Emisar D8K with 4 or 8 XP-E colour LEDs may rival the maximum lumen output, though probably not the sustained brightness. It should be noted that the (non-monchromatic) full spectrum green CSLNM1.F1 performed very well in my tests despite the low current, most likely due to having a wider range of wavelengths. I would be interested to compare the CSLNM1 vs Getian GT colour for monochromatic colours (e.g. red and blue) - please donate if you want me to do that review!


If you need a bright and throwy red, green, or blue flashlight, the Convoy M21H is a good option. This LED is also available in other Convoy flashlights, all of which are relatively throwy (the L21B will have the longest throw with a "pencil like" beam). The zoomable Z1 may be useful for the illumination aspect of light painting and night photography. I would like to also see the Getian GT coloured LEDs in the more floody S11, which is the smallest Convoy body suitable for 7070 size LEDs. If Convoy's floodier (25 and 36 degree) 35mm optics are compatible with this LED , I would like to see them added as an option in the product listing.


M21H Outdoor Beam Shot. f/5.6, 1.6sec, ISO400.
M21H Outdoor Beam Shot. f/5.6, 1.6sec, ISO400.

Conclusion


Positives:

  • Impressive maximum and sustained coloured light brightness/lumens.

  • Impressive peak beam intensity/throw.

  • Decent runtime.

  • Good value for money.

  • Simple user interface, with ramping or stepped brightness, and last mode memory.

  • Moonlight mode.

  • Internal USB-C charging.

  • Compatible with diffuser and tripod mount.


Negatives:

  • Head size is too large for connecting to light painting tools.

  • No battery included.

  • Ramping is too fast at lower brightness modes.


If you want best in class brightness and impressive throw from a single colour red, green, or blue LED, then the Convoy M21H is an excellent choice. Convoy offers a huge range of flashlights with coloured LEDs for niche uses. However, I would like to see some floodier TIR lens options in the light's listing, as well as use of the Getian GT colour LEDs in a flashlight with a smaller head size for connecting to light painting tools.




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