The Walksnail Moonlight camera/VTX kit emerges as a direct competitor to the popular DJI O3 Air Unit. Offering stabilized 4K recording and a robust performance that rivals, and in some aspects, surpasses the DJI O3, the Moonlight kit presents itself as an interesting option. This review delves into my personal experiences with the Moonlight, comparing it head-to-head with the DJI O3.
New to Walksnail FPV system? Learn more in this article: https://oscarliang.com/setup-avatar-fpv-system/
Still wondering which FPV system you should get in 2024? Check out my buyer’s guide: https://oscarliang.com/fpv-system/
Where to Buy?
Get the Walksnail Moonlight camera/VTX kit from these vendors:
It comes with the following accessories:
- 1x Spare screws for mounting
- 1x Wire harness for firmware upgrade
- 1x Wire harness for connecting the flight controller
- 1x ND8 Filter
- 2x Antenna
- 1x Manual
Specifications
- Firmware name: AvatarMoonlight_Sky_X.X.X
- Transmitter Power: FCC:<1000mW; CE:<25mW
- Image Sensor: Starlight sensor
- FOV: Max 160°
- Aperture: F2.1
- Shutter: Rolling shutter
- ISO: 100-25600
- Recording resolution: 4K@30/60fps,2.7K@30/60fps,1080p@100/60fps,720p@60fps
- Max Mbps: 150Mbps
- Video format: MP4 (H.264)
- 3D DNR: Support
- Gyroflow: Support
- Built-in EIS: Support
- Wide Power Input: 7.4V-25.2V
- Power consumption: [email protected], [email protected]
- Memory card type: U3 MicroSD, Max 256G
- Camera size: 19.6mm*19mm*24mm
- VTX size: 15.3mm*34.5mm*34.5mm
- VTX Installation hole distance: 20*20mm/25*25mm (M2)
- Weight: 38.5g(Antenna not included)
- OSD: Canvas mode
- Latency: Average delay 22ms
- Antenna: 2 (IPEX)
- Filter: ND8
- Antenna Polarization: LHCP
- Antenna Average Gain: 1.9dBi
- Antenna VSWR: ＜1.5
- Antenna connector: IPEX-1
- Antenna Dimension: 15x45mm (without cable)
- Antenna Weight: 2g
Moonlight is compatible with the following FPV goggles / receiver module:
It’s not compatible with DJI Goggles.
What’s the Moonlight Kit?
Similar to the DJI O3, the Walksnail Moonlight is a camera/VTX combo that offers 4K recording capabilities while streaming HD live videos back to the FPV goggles on the ground. This kit potentially eliminates the need for additional action camera on the drone, simplifying setups and reducing overall weight and cost.
The Moonlight not only records in 1080p, 2.7K, and 4K resolutions but also features electronic image stabilization (EIS). The camera settings allow for manual control, including shutter speed and ISO, which is crucial for capturing high-quality footage in various lighting conditions.
You can learn more about the DJI O3 here: https://oscarliang.com/dji-o3-air-unit-fpv-goggles-2/
Design and Build
The Moonlight has a robust build, with a durable metal shell that serves as a heatsink. It is slightly larger and heavier than the DJI O3 air unit, weighing around 43g without ND filters, compared to the O3’s 40g. However, the Moonlight offers better mounting flexibility with both 20x20mm and 25.5×25.5mm M2 mounting holes, enabling direct mounting onto most drone frames on the market.
The Moonlight camera has a 19mm width just like any standard micro camera. It’s easier to mount than the O3’s non-standard 20mm size, though it is somewhat longer front to back. The yellow silicone spacers in the mounting holes help to dampen quad vibrations, protecting the built-in gyro.
While the Moonlight also features a dual antenna setup for consistent signal, the antennas are individual, unlike the DJI O3’s more convenient 2-in-1 design. The antennas may be a bit challenging to plug in, luckily you probably only need to do this once.
The camera is connected to the VTX via a MIPI connector and it’s detachable.
The camera cable lengths and antenna lengths are similar between the O3 and Moonlight.
Dimensions and Weight Comparison:
| Moonlight | O3 | |
| Weight | 43g | 40g |
| VTX Dimensions (mm) | 34.5 x 34.5 x 15.3 | 30.5 x 30.5 x 14.5 |
| Camera size (mm) | 19.6 x 19 x 24 | 20 x 20 x 21.2 |
The Moonlight camera’s starlight sensor boasts a 160° FOV in a 16:9 aspect ratio, with an f/2.1 aperture and an impressive ISO range of 100 to 25600. It supports 4K recording at up to 150Mbps and is compatible with micro SD card up to 256GB.
It comes with an ND8 filter which is easily attachable and detachable, offers lens protection but is over 2 grams heavier and considerably bulkier than typical O3 ND filters. It can possibly be obstructed by the front standoffs, making it difficult to use in certain FPV drone frames without modifications. Anyway it’s nice to have it included in the kit. I wish ND16 is also included, for bright sunny day and snowy days, but ND8 should be quite versatile for many situations.
The absence of a USB port on the Moonlight VTX means SD card removal is necessary for footage transfer and firmware updates, which might be less convenient compared to the O3.
Another advantage of the DJI O3 is its 20GB internal memory. While it may not seem significant as it only holds about 20 minutes of footage, it can save you from going home empty-handed when you forget your SD card. I wish the Moonlight offered a similar feature.
Moonlight’s camera cable is about 12cm long while the antenna wires are about 5.5cm (excluding the plastic tube part).
Latency and Flying Experience
The Moonlight provides a flying experience similar to other Walksnail Avatar VTX and cameras, with the added advantage of onboard recording.
In terms of latency, the Moonlight matches or slightly outperforms the DJI O3, particularly in the 60fps mode. While the latency in 30fps mode is a bit higher than 60fps, it’s notably better than the O3 also, offering a more manageable flying experience. The O3 performs the best in 100fps mode, but then your recording would also be in 100fps, which is not ideal in some cases.
Thanks to Moonlight’s starlight sensor, the system’s low light performance is particularly impressive, outperforming the DJI O3 in challenging lighting conditions. Its ability to capture clear and detailed images in near-darkness is a significant advantage for night flyers.
I’ve noticed that the Moonlight is just as susceptible to jello as the O3, if not more. To combat this, ensure your FPV drone is well-tuned and consider soft-mounting the camera if possible. For guidance on tuning your quads, check out my tutorial: https://oscarliang.com/fpv-drone-tuning/. Gyroflow seems to be pretty effective in minimizing jello so that’s worth a try.
Image Quality and DJI O3 Comparison
The Moonlight was tested using the latest firmware at the time of publishing (37.42.3).
The Moonlight camera offers manual settings that will appeal to experienced pilots, currently you can adjust the following settings:
- Resolution / Frame Rate
- Sharpness
- Exposure Value
- Saturation
- White Balance
- ISO
- Shutter Speed
However, it’s worth noting that unlike the DJI O3, the Moonlight lacks flat color profile or 10bit recording capability and doesn’t offer a native 4:3 mode at the time of testing. Having native 16:9 means the video is more zoomed in after image stabilization is applied in post (such as Gyroflow).
In terms of image quality, it’s quite subjective. The Moonlight impresses with clear contrasts and sharpness, the advantage is especially noticeable in low light.
Here’s a side-by-side comparison between the Moonlight and O3, both set to 4K 60fps with auto settings. Both cameras produce very nice-looking images; the Moonlight appears a bit sharper and warmer, while the O3 has slightly less distortion and a marginally wider field of view (Wide setting).
In night time conditions, the Moonlight is the clear winner in low light. It supports ISO settings up to 51200, in contrast to the O3, which maxes out at 6400. Although the Moonlight excels in low-light scenarios, the high ISO can introduce noise and graininess, potentially making flight challenging.
One point of critique is the auto shutter speed’s exposure changes, which can seem a bit unnatural. Hopefully, this can be addressed in future firmware updates. Here’s a short clip from the Moonlight camera capturing a grey winter day, with Gyroflow applied.
Modular Design
Disassembling the Moonlight VTX reveals a dual board design similar to the O3. One board functions as the video transmitter and the other as the video recording board. Caddx has designed it in such a way that the two boards can be separated. This makes repair more cost effective as you only need to replace the damaged board, not the whole unit.
According to Walksnail, in spring 2024, they plan to release a record-only unit (it includes only the Moonlight camera and recording board). This can be connected to any Walksnail Avatar VTX, offering a modular approach that reduces costs and simplifies replacements.
Firmware Updates
During my testing, Walksnail had released 4 firmware updates, showcasing their commitment to improving the Moonlight camera. While it was a little bit annoying for the reviewers having to retest it every time, hopefully when it gets to the customer’s hand, most of the issues would have been addressed.
The firmware update process is slightly cumbersome due to the need for a special cable to bridge the two boards. Firstly, it would be hard to reach these tiny connectors if you have a tight frame, which probably means you’d have to take the drone apart every time you want to update the Moonlight. Secondly, you cannot lose this tiny cable or you won’t be able to update.
Power Consumption Testing
25mW Output Level
| Input Voltage | Not Recording | 1080p 100fps | 4K 60fps |
| 7V | 1.6A | 1.8A | 2.0A |
| 9V | 1.3A | 1.4A | 1.55A |
| 12V | 0.95A | 1.05A | 1.2A |
1000mW Output Level
| Not Recording | 1080p 100fps | 4K 60fps | |
| 7V | 1.8A | 1.95A | 2.3A |
| 9V | 1.4A | 1.55A | 1.8A |
| 12V | 1.05A | 1.15A | 1.35A |
Power consumption tests at various output levels show that the Moonlight draws significant current, especially when recording in 4K. The difference in current draw between the minimum (25mW) and maximum (1000mW) power levels isn’t substantial. For safety, a 9V BEC with at least 2A, preferably 3A, is recommended.
An important note: the VTX underreports the input voltage by about 0.4V. This discrepancy is not an issue when powered by a BEC with constant voltage, but if you power it directly from a battery, it can make you want to land earlier than you should.
How to Use
Connecting the Moonlight VTX to the flight controller is exactly the same as other Walksnail VTX. You power it from a BEC or directly from the battery, and connect RX/TX pins to a spare UART on the FC.
In the goggles’ menu, you can select the desired resolution and frame rate for recording. The FPV system’s frame rate setting impacts the available recording resolutions.
- Setting frame rate to high, only 1080p 100fps/60fps/30fps are available.
- Setting frame rate to standard, you get 4k 60fps/30fps, 2.7K 60fps/30fps as well as 1080p60fps/30fps (100fps is not available).
By default, pressing the DVR record button on the goggles starts both the VTX and goggles recording.
Camera settings like frame rate and resolution take about 4-5 seconds to reboot after changes.
Built-in EIS (image stabilization) is only available in 2.7K resolution, not available in 1080p / 4K. Stabilization is applied in the recorded video directly. No gyro data is recorded when built-in EIS is enabled.
But when Built-in EIS is disabled, the VTX records gyro data in a separate file along with the video (.gcsv) which you can import in Gyroflow for image stabilization in post, which I believe yields better result than the built-in EIS. Therefore I recommend disabling built-in EIS and use Gyroflow for image stabilization.
In Gyroflow, camera and lens profiles are automatically detected and loaded when you import footage.
- 4K 60fps bit rate: 150Mbps
- 2.7K 60fps bit rate: 100Mbps
- 1080p 100fps bit rate: 100Mbps
- 1080p 60fps bit rate: 80Mbps
Best Settings
Walksnail seems to be still refining the firmware for the Moonlight, adjustments to settings and the introduction of new features are ongoing.
Therefore, I will hold off on publishing my preferred settings for the Moonlight until a stable firmware version is released, given that changes are anticipated prior to that.
Conclusion
The Walksnail Avatar Moonlight camera/VTX kit is a strong contender in the HD FPV market. It offers 4K recording, impressive low-light performance, and flexible camera settings.
Purchase the Walksnail Moonlight camera/VTX kit from the following vendors:
While it shows promise, the Moonlight still has areas for improvement to match the DJI O3, such as the addition of a flat color profile, 10-bit color, an easier firmware update process, and the inclusion of internal memory and a USB port. The O3 maintains an edge as a more sophisticated and powerful camera. Nevertheless, for those seeking a lighter Walksnail FPV drone without the need for a heavy camera like a GoPro, the Moonlight presents a compelling alternative.