Review: Runcam Split 4 Camera – Making the World’s Smallest 4K FPV Drone

The Runcam Split 4 is an HD camera capable of recording 4K videos, designed to be mounted in tiny whoops or “toothpick” micro drones. I managed to install it in a 65mm whoop, possibly the smallest 4K FPV drone.

The World’s First 4K 65mm Tiny Whoop

I simply replaced the BetaFPV Nano HD camera in the Beta65X HD with the Runcam Split 4. This tiny 65mm FPV drone can now record 4K videos! :)

It was easy to swap out the camera, as they both have similar size, except the lens module. I had to drill a couple of holes in the canopy to mount the lens.

I also had to trim away some plastic in the canopy to access the buttons. Still need to add protection to the lens, maybe some foam or a lens cap.

The weight without LiPo is only 34g, 2.5g heavier than before. This is a 2S whoop, so the extra weight should be manageable.

I am sure you can do the same upgrade easily on other micro drones too :)

Where to Buy Runcam Split 4

It comes with a “nano to micro” adapter (14mm to 19mm width), some M2 screws, standoffs and nuts, and a 3-pin JST cable for connecting to your FC.

Specs and Features of Split 4 Camera

The Runcam Split 4 is an HD camera, but it can be used as an FPV camera at the same time. The averaged latency according to Runcam is 55ms, slightly higher than dedicated FPV cameras, but low enough to be flyable.

It’s one of the smallest / lightest HD cameras that can record 4K videos. With the 25.5×25.5mm mounting holes, it can be mounted on top of “whoop style FC” – many tiny whoops and toothpick builds use this type of FC.

When the camera is powered off by accident (e.g. battery ejected in a crash), it will automatically save the video, so you won’t lose the footage. (it will cut off the last 3-4 seconds, but better than losing the whole video!)

You can control the camera using your switches on the radio (start/stop recording, navigate OSD menu), simply by connecting the camera to the flight controller, and set it up in Betaflight.

The Split 4 camera supports 5V to 20V as input voltage, which means you can power it directly from a 2S, 3S or 4S LiPo if you want, but it’s not recommended as voltage spikes could damage it. It’s best to power it from a BEC.

Closer Look at the Split 4

The Split 4 only weighs 10.2g!

Compared to the previous Runcam Split 3 Nano, the lens module sizes are similar, but the Split 4 has a different lens – appears to have wider aperture.

Left: Split 4; Right: Split 3

The PCB is slightly wider in the Split 4.

Top: Split 3; Bottom Split 4

Here are some close up shots of the PCB.

The ribbon wires are very strong and well protected, almost impossible to pull off from the PCB or the lens module. They used the same design/material in the older Split 3 and it’s been proven to work reliably.

The lens module is a 14x14mm nano size camera, with M2 screw holes on both sides.

There are two buttons – Power/Shutter button and Mode button. You can use these buttons to change settings through the OSD menu.

Alternatively, you can also solder your Runcam joystick to this camera, it’s much easier to navigate the menu with it.

They have added shutter speed to the image settings, which is amazing. This is a must have setting if you were to use ND filter and create silky smooth FPV footage, having a fixed shutter speed means your video exposure will be a lot more consistent.

Solder pads are well sized for easy soldering.

I am a little concerned by how far the SD card sticks out. But it doesn’t seem to be an issue though in my Beta65X build, but something to take note of.

Image Quality

See HD and FPV feed image quality in this video, comparing to the Split 3 Nano:

Watch it and decide for yourself, here are some of my own findings:

  • Field of view is wider, especially in FPV mode
  • Colors in FPV feed are much nicer to look at, more natural
  • Saturation in HD is much lower in the new version, possibly better for color grading in post
  • It has less image distortion than the previous Split 3
  • Audio is better
  • Default Sharpness and WDR are similar
  • Bit rate of 4K raw footage is 61Mbps, a 40-second video is about 310MB

And I think I found a problem with FPV feed stuttering when recording in 4K. It doesn’t always happen and seems to be random. Changing PAL/NTSC didn’t fix it. I’ve contacted Runcam about this and see if they can replicate the issue and fix it in a software update. Update: issue fixed in the latest version (1.1.5), hopefully all production units has this firmware (or newer).

Runcam Split 4 Connections

Here are the buttons and pin-out of the Runcam Split 4.

The only important connections are VCC (red), GND (black) and Video (yellow). You don’t have to connect RX and TX, these are for connecting to the FC if you want camera control

Basic Operations

How to operate the Runcam Split 4:

  • To Power on, long press the Power/Shutter button, solid blue LED means the camera is powered on
  • Press the Power/Shutter button to record, and blue LED will begin to blink
  • To access the OSD menu and change camera settings, long press the MODE button (when you are not recording), you will see a solid orange LED
    • Press Power button to move to the next setting
    • Short press MODE button to change setting
    • Long press MODE to exit

How to Setup Camera Control?

You can start/stop recording and navigate through OSD menu using the switches on your radio. Here is how to set it up.

First you have to find a spare UART on your FC, and connect the TX and RX pads.

Enable “Runcam Device” for this UART in the Ports tab in Betaflight.

And assign switches to these modes.

9 thoughts on “Review: Runcam Split 4 Camera – Making the World’s Smallest 4K FPV Drone

  1. Jordi

    Hi Oscar,

    Great review, congratulations and thanks for all information. I would need your support to clarify the Image Quality point: when saying “Field of view is wider, especially in FPV mode” and “Colors in FPV feed are much nicer to look at, more natural”, are you referring Split 4 over Split 3 (you mean 4 has wider FOV and much nicer to look at than 3)?

    Thanks in advance,

    Reply
  2. qemay

    The yellow wire is only for FPV which is a standard NTSC/PAL SD res. The HD/4K res is only recorded on the SD card.

    Reply
  3. Popwax

    Is the sensor in native 4:3 aspect ratio and stretched to 16:9 for recording (like GoPro SuperView)? If it’s true, is it possible to record in native 4:3 aspect ratio without stretching?

    Reply
    1. Oscar Post author

      As far as i know this is not possible in the Split series, but possible with the Runcam 5 series (box camera).

      Reply
  4. todd

    Doesn’t having just a single wire (yellow one) coming from the camera limit you to non-HD output (like a TV’s composite output)?

    Reply

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