With all due respect, that gimbal is not really in the same class. It might be fine for doing still shots, but as I found out yesterday, in low light conditions, you need good vibration isolation, even for stills. This mount appears to "hard mount" to the bottom F450 plate.
For video, I think this gimbal will be severely limited. It uses a small servo in the tilt axis, in a direct drive configuration, which means for small corrections, there will be a "stair-stepness" to the gimbal movements, even with hi-res 10/12-bit higher end digital servos, which a $99 gimbal is not going to have. In the roll axis, they are using an even smaller micro HS-55 analog servo, with a mechanical linkage, which introduces a measure of slop, or backlash. From the geometry, it appears that even in the roll axis, they are sticking to a 1:1 ratio between angular movement of the servo arm and the roll angle. Small movements will not be smooth enough, in my opinion. finally, it has been my experience that the Naza and WK-M do not play nice with analog servos.
When Andrey and I set out to do this, the purpose was to address all the issues that limit excellent video performance. I had a checklist of what I knew were areas that we needed to address. My goal was to have a GoPro-specific gimbal that would fit on an F450 quad, and that would be optimized for producing great video. Here was my checklist of features that I think we needed to achieve this:
- Each axis needs a belt drive, in order to provide extremely smooth movements, even for small corrections. With higher than 1:1 reductions, however, there is speed penalty. From my own tests, I've found that a 2:1 ratio will provide the smoothness required, assuming hi-res digital servos are used, while still providing enough speed, if these servos are also fairly fast (.10-.11s/60 deg., or faster...). Speed is important so that the gimbal corrections don't lag platform movements.
- High speed, high resolution digitals servos are a must, and they should be programmable. We chose the Hyperion DH16-SCD digital minis, for this GoPro-specific gimbal, for several reasons. First and foremost, they are the highest resolution digital mini-size on the market. Most "higher res" digital minis are 10-bit, like the Savox SH-1357, for instance. The other reason is that these are easily programmed, using a PC app. What we do is open up the throw range to a full 180 degrees. This allows the full +/- 45 degrees of motion, for both axis. I've also used the programming app to fine-tune the deadband space to the WK-M/Naza's gimbal outputs, which improves smoothness.
- There needs to be an effective vibration isolation scheme. Even the tiniest of vibrations will come through to the video, usually in the form of "jelly roll". In my tests so far, I've not used the isolators at all, as I wanted to see the worst case for platform-related vibrations, so the gimbal is hard-mounted to the F450 lower plate. Now that I've minimized the prop-related vibrations, I'm going to install the vibration isolation plate.
- Finally, I wanted to make sure that this gimbal was compatible with using the GoPro's waterproof case. With my old GoPro, I ended up scratching three lenses, with even the mildest of "mishaps" (rolling over, on the grass, was one...), so I won't use a GoPro now without the case.
Anyway, this gimbal/mount is very robust, it has a very effective vibration isolation/mounting scheme, and it meets/exceeds the criteria that I've established above for achieving excellent onboard video performance. Attached are a few shots of its current configuration.
-- Gary