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  • Stephen Knight

Flashlight Review: Convoy M21C GT-FC40

Updated: Feb 3

I'm a big fan of Convoy flashlights / torches, due to their high quality and low price. The M21C range of lights are designed for high output, in a mid-sized package that runs off just one Li-ion 21700 battery. Can the M21C compete with larger, "soda-can" sized flashlights for night photography and light painting illumination?


This flashlight was purchased with my own funds.


The Convoy M21 range of flashlights (or torches in the Queen's English) are high output, medium sized flashlights that run off a single unprotected 21700 Li-ion battery. The M21A has a large head and is quite throwy, the M21B has a compact head, and the M21C and M21D have a large head, and pitched somewhere between being a floody and throwy light depending on the chosen LED emitter. Emitter options for the M21C include the high-CRI Getian GT-FC40 (reviewed), Luminus SST-40 and SFT-40, Cree XHP70.2, Osram CULPM1.TG, CSLPM1.TG, and CSLPM.F1 (Green). The M21C has a mechanical tail switch, 12 group user interface, and no USB internal charging. The M21D (which has recently replaced the M21C-U) uses the Cree XHP70.2 emitter, has a side e-Switch, choice of stepped or ramping brightness, and USB-C internal charging.

The reviewed model is the M21C with GT-FC40 emitter, which is a large format (7070) high-CRI LED emitter, in an orange peel (Convoy call it "crumpled") reflector. The flashlight head is 55m diameter, body 28mm diameter, and 163mm in length. The LED runs off a 12V 2.5A driver. There is a single mechanical tail switch, and the unprotected Li-ion 21700 battery (optional) can be inserted by unscrewing the tail cap. I used a 5000mAh Samsung 50E 21700 battery for my tests.

As usual with Convoy, the light came in a padded cardboard box with no extras, and no instructions. Instructions are available on the product page on Convoy's website. The M21C and M21D will both fit U-shaped tripod mounts from Kaidomain. I was sadly unable to find a compatible diffuser.

Convoy M21C GT-FC40 Flashlight
Convoy M21C GT-FC40
Size comparison - Convoy M21C (left) vs BLF Q8 (right)
Size comparison - Convoy M21C (left) vs BLF Q8 (right)

User Interface

The Convoy M21C uses a version of Convoy's 12 Group user interface. By clicking the tail switch 20 times you go into configuration mode and can choose between 12 different mode group options, and turn mode memory on and off. I prefer mode 10 which is 1%, 10%, 35%, 100%.

As per the Convoy S2+, a full click of the tail switch is on/off, and a half press moves to the next mode. The strobe is unfortunately alternating frequency instead of constant frequency, though as this light is too large for connecting to light painting tools, this isn't an issue. Loosening the tail cap will mechanically lock the light out for safety.

Beam and Output

The GT-FC40 is a relatively large 7070 format emitter, so naturally this will create a "floody" beam, with a large hotspot. The crumpled reflector smooths out the hotspot to spill beam transition. However, the reflector is very deep, which creates a much narrower beam than I would expect at approx. 60 degrees, vs the BLF Q8's 80(ish) degrees. Some users may prefer the narrower beam, but personally I would like it to be 20 degrees wider. Since the review, I have added D-C-Fix diffusion film to the lens which creates a beautifully smooth floody beam. The hotspot can provide useful illumination up to around 150m distance.

The GT-FC40 is quite unique in that it is a large format LED with high colour rending (high-CRI) at 95CRI. Most other LEDs of this size and output are around 70CRI. The impressive CRI means that illuminated scenes will not appear to be washed out, with tree trunks and leaves for example appearing much more realistic. There are two colour temperature options 4000-4500k and 5000-5500k, of which the latter was reviewed. The tint is perfect, bang on the BBL Line, so no hint of green or purple. The tint and colour temperature are also very even between the hotspot and spill beam, much better than the fried egg look from Cree emitters.

The M21C GT-FC40 managed approximately 2500 lumens for 4 minutes, and then the heat management lowered the brightness to approximately 1000 lumens, where the output remained stable. On 35% mode, the light remained stable at approximately 1000 lumens, and the runtime was 140 minutes with a 5000mAh battery. This is all pretty impressive for a high-CRI flashlight running off a single 21700 battery.

Whilst there are plenty of flashlights with much higher initial brightness, these are rarely suitable for light painting and night photography illumination purposes as the the maximum brightness rapidly reduces in brightness - for example if you set up a typical 10,000 lumen light for a backlit photo, by the time you actually get around the taking the photo 30 seconds later, the brightness will have reduced to just 5-15% of the initial brightness. This is why I consider sustained brightness to be more important than maximum brightness in my reviews.

Convoy M21C GT-FC40 Crumpled Reflector
Convoy M21C GT-FC40 Crumpled Reflector

For night and light painting photography purposes, the M21C GT-FC40 is excellent for bright high-CRI moving illumination, backlighting (amusingly known as still-houettes), and for use with backlight scanners (such as the LACE Backlight Scanner). Due to the narrow beam angle and lack of compatible diffuser, it is not so useful for static illumination.

Beam comparison -Convoy M21C GT-FC40 (left) vs BLF Q8 XP-L HI (right)
Beam comparison -Convoy M21C GT-FC40 (l) vs BLF Q8 (r)
Convoy M21C GT-FC40 Woodland Beamshot
Convoy M21C GT-FC40 100% output. f/5.6, 2sec, ISO400
Backlighting with Convoy M21C GT-FC40 f/5.6, 1.3sec, ISO400
Convoy M21C GT-FC40 35% output. f/5.6, 1.3sec, ISO400

Can the M21C replace multi-battery "Soda Can lights"? Maybe not the GT-FC40 version, but certainly the XHP70.2 version of the M21C or M21D can compete with the chunkier BLF/Sofirn Q8, Sofirn SP36, Fenix LR35R, in terms of sustained brightness. These lights all have a short-lived (<90secs) brighter maximum output. The M21C GT-FC40 can also compete with the far more expensive (but zoomy) Ledlenser MT18 is terms of maximum and sustained brightness.


Things I liked:

  • Good maximum brightness for a high-CRI light

  • Good sustained brightness for a high-CRI light

  • Excellent tint

  • Very good value for money

  • Configurable user interface

  • Good size to sustained lumen ratio

  • Can use 3rd party tripod mount

Things I didn't like:

  • Narrower beam than expected (60 degrees)

  • No compatible diffuser

  • No internal charging (note: the M21D has internal charging)

The Convoy M21C is great value for money, and has good maximum and sustained high-CRI output. A "floody" emitter in a "throwy" reflector is an odd choice though, and I would have preferred a wider beam angle. If you don't need a high-CRI beam, then I would recommend the 4000lm M21D XHP70.2 instead which has higher 4,000lm maximum and 1,500lm sustained brightness , choice of ramped or stepped brightness levels, and USB internal charging.

Product link (affiliate):

Convoy M21C GT-FC40 15% off with Code "STEPHENKNIGHT".

Product links (non-affiliate):


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2 Kommentare

Vincent Tanu
Vincent Tanu
13. Juli 2021

Great review! Have you tried Convoy S11 GT FC40? It's said to have 87deg beam (in the Aliexpress listing).

Do you find the CRI critical in your profession?

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Stephen Knight
21. Juli 2021
Antwort an

I've had a look at the Convoy S11 with GT FC40, but it slowly reduces from max brightness almost immediately, and can only sustain around 700 lumens. Not really worth upgrading from my LH351D S2+.

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