Category: Design & Tune

Stabilising footage generally has a huge impact on the sharpness and overall quality of the image. On the larger Cinelifter systems I try to use as little stabilisation as possible to maintain resolution. GoPro stabilisation such as ReelSteady often discards more than 30% of the original image! When using instagram, facebook or youtube for delivery it is difficult to tell what a hit the quality has taken.

Ideally you want to have your shutter at 180 degrees (twice your frame rate) so for 25fps this would be a 50th of a second, at 50fps it would be 100th of a second etc. This creates a natural and believable amount of motion blur in the image. You might say this is a cinematic look. Most freestyle pilots stick to a 180 degree shutter and no stabilisation. On a bright day even at ISO 100 you will end up with too much light to get a good exposure with these lower shutter speeds. This issue is solved using ND filters. I commonly use an ND8 or ND16 on sunny days to allow me to get the correct exposure.

If you are flying aggressively and using a lot of stabilisation off camera, eg with ReelSteady then using a 180 degree shutter can cause artefacts in the stabilised image. Many people think this is vibrations from the drone but it is actually the result of taking a frame that has been blurred with high speed movement and making it appear stationary – stabilising it. For this reason it is a good idea to use a 90 degree shutter when using ReelSteady. This means a shutter of 100 at 25fps or 200 at 50fps. As you get used to moving the drone around more gently and smoothly you can go back to a 180 degree shutter in some cases as the stabilisation will be working less hard.

These are my settings for most situations:

> 2.7k 4:3 50fps or 4k 4:3 25fps
> Wide
> In camera stabilisation: Off – this means I can use the unstabilised footage, de-fish and crop the top and bottom to make the image 16:9 or use ReelSteady to stabilise it
> Low light – off
> Shutter – discussed above
> EV Comp – no effect as GoPro is always exposed manually
> White Balance – 5500k outdoors, sometimes auto for indoors
> ISO Min & Max – always set to the same and as low as possible to prevent the camera laddering the exposure.
> Sharpness – Low, If working with an ISO > 100 then it’s much better to avoid in camera sharpening. With RSG, sharpening in post after the crop and interpolation has happened will produce a better result. Having said that I often shoot medium because sharpening in post is demanding even with a really good computer, this is for convenience though not IQ
> Flat Colour – On
> High Bitrate – Yes

Some more shutter speed info I posted on facebook:
Welcome! It took me a while to work out! In Benoit Finck’s clip above he has made totally the right decision of course. Sometimes with less movement in the shot you can get away with a 100th shutter at 50fps (180 degrees), as each frame is exposing for the same amount of time at a 90 degree shutter at 25fps.. having said that shooting a 180 degree shutter at 25fps results in a 50th of a second shutter speed and you have to be very careful to fly smooth and not put in any big moves or the motion blur artefacts are very obvious. Freestyle pilots and anyone in film/tv love a 180 degree 24/25/30fps shutter. You get a very natural look to the movement but you can’t stabilise it aggressively. A lot of cinelifter pilots prefer a 90 degree shutter at 24/25/30fps as there is so much movement in a lot of the shots it kinda tames the blur a little and gives more scope for stabilisation in post.

If you are flying really smooth and gentle on the sticks with no fast/uneven pan or tilt you can use a 50th of a second but even then artefacts will creep in sometimes. At 100th of a second you can be a little more agressive with your movements, at 200th the bar is raised again, you do still see artefacts from time to time but it’s very rare for it to ruin a shot. 50th, 100th or 200th are all valid depending on the situation. (60th, 120th, 240th in NTSC)

For UK drone ops: alex AT designtuneoperate.co.uk

Many people running larger motors on x8 setups and using the onboard BEC on the Matek F722-HD or similar FC have reported the video feed from the air unit freezing during aggressive flying.

It isn’t the current draw of the air unit that causes the issue, it’s the lack of capacitance before the FC regulator which is unable to cope with the voltage fluctuations from 8 motors and active braking. If you have smaller motors ie 2806.5 on 6s then some people have reported no issues when using the BEC on the FC, personally I wouldn’t risk it. With larger motors ie 2812 on 6s it is certainly a bad idea to use the FC BEC or one of the Matek/iFlight micro BECs. The solution which most operators have gone for is a D36V28F12 Pololu with a 390uf 35v low ESR cap on the input side of the Pololu.

For 8s rigs a separate lipo to run the air unit is recommended

Here is where you can get the required components:
https://www.pololu.com/product/3786 – US
https://proto-pic.co.uk/product/pololu-step-down – UK
https://www.ebay.co.uk/itm/183673621998 – Caps UK

Lots of people have been asking about PID tuning recently so I thought I would try and condense all the key info into a safe baseline tune that will start to get people in the right direction without having to copy paste a tune.

This is aimed as a starting point for x8 BF4.2 builds on 7″ or 8″ props; Siccario // Thicc. YMMV, the real value of this post is the explanation of each of the key settings

Master Multiplier: 1.2 – this turns up P I and D and makes the drone push harder to correct for stick inputs and against external forces. – This has been reduced from my initial suggestion to allow for I-term issues caused by loose cameras as suggested by Sam Sanford. Extra P & D gain is added further down this post to keep the drone following set point

PD Balance: 1.4 – this mellows out P bounce back and resists all movement by turning up the D term – this really helps make things smooth. Setting this balance too high can result in hot motors, ideally this balance is determined using blackbox logging. 1.4 is a safe bet and you can see how it feels a couple of clicks higher, checking motor temps and listening for motor trilling as you go

Stick response: 0.5 – this turns down a boost effect that pushes the drone more aggressively when the sticks are moved fast – this generally isn’t ideal for Cine stuff as you want smooth footage

I Term Relax Cutoff: 5 – this is in the right hand panel on the tuning tab. Turning this down from the default setting prevents I term accumulating when the drone is rotating faster than the threshold. This tames slow wobbles after fast flips and rolls which can happen when a larger drone is not tracking set point well

Anti Gravity Gain: 10 – this is in the right hand panel as well. Turning this up from default will reduce the amount of nose wobble you get when blipping the throttle or powering out of a dive. Settings higher than 10 might be needed but the sticks will start to feel stiff with large throttle movements

Filtering: It is possible to increase prop wash performance by reducing the amount of filtering (less filtering = bigger slider number in GUI = filter cutoff at higher frequency in hz!).

On bigger drones you really need to be using blackbox info to make adjustments before you move away from having the filter sliders at 1. You don’t fully benefit from reduced filtering unless you are increasing your PD gain at the same time.. otherwise you are sacrificing the ability to fly with damaged props without taking full advantage of the improved flight performance.

RPM Filtering is highly recommended. Once setup, put the Dynamic notch to the following settings so it can focus on the lower frequencies while RPM filtering does the higher ones:
Dynamic Notch Width Percent: 0
Dynamic Notch Q: 250
Dynamic Notch Min Hz: 90
Dynamic Notch Max Hz: 350

PD Gain: 1.3 start with your PD gain at 1.3, if you are used to flying 5″ on BF defaults it should start to feel much better, probably a little loose still. If you want to get better prop wash handling and a more dialed in feel then you can slowly increase the P and D gain, checking motor temps each time until you hear the motors trilling in the air. Then back it off a notch or two. If the motors are already trilling or getting hot at 1.3 then reduce the PD gain

For drone ops: alex AT designtuneoperate.co.uk

After a few requests I thought I would write this quick guide on how I made the arm braces for my Siccario.

Update: Andy Shen now ships all new Siccario with a carbon version of these struts 👌🏻 They are also avail on his spares page.

I ordered 4 of these track rod end joints/knuckles and used a Dremel to cut them back so the ball inside is flush with out outside of the knuckle, it’s a bit fiddly but it means the knuckle fits under the motor:
https://www.ebay.co.uk/itm/362789871012

You will also need 2x 220mm lengths of stainless threaded bar, you can order 2x 300mm here and cut it down with a Dremel or similar. You may need to adjust the length but 220mm is a good place to start:
https://www.ebay.co.uk/itm/162605737481

Once you have the knuckles cut down and the bar the right length, add an M3 nylock to each end, fitted backwards as per the pictures, then attach a knuckle to each end:

Finally attach to the Siccario by removing one of the M3 motor mount bolts and replacing it with a longer 25mm bolt so there is enough length for the knuckle as well. I also have a washer between the knuckle and the carbon:

Enjoy reduced vibrations with those larger motors!

It is now possible to get the feed from your DJI v1 goggles onto your computer thanks to some clever people here:
https://github.com/fpv-wtf

Here is how it is done on OSX via terminal:

Install homebrew:
/usr/bin/ruby -e “$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)”
add Homebrew’s location to your $PATH
export PATH=”/usr/local/bin:$PATH”
and then:
git -C $(brew –repository homebrew/core) checkout master
Install node.js:
brew install node
Install ffmpeg & ffplay: (takes ages as it has to compile)
brew install ffmpeg

Get the required files from the clever dude’s github: (green code button then download zip)
https://github.com/fpv-wtf/voc-poc
Unzip, then type cd into a new terminal and drag the unzipped folder onto the terminal window, then press enter. This focuses the terminal window on that folder.

1. Connect your goggles via usb, and power them on with goggle battery
2. Make sure temp control is off on the DJI FPV system (this works better with Air Units. Vistas will get hot fast)
3. Power up your drone, (props off) wait for the picture in your goggles
4. Run the following code in the terminal window that is focused on the folder you downloaded from github:
node index.js -o | ffplay -i – -analyzeduration 1 -probesize 32 -sync ext
5. Sometimes it takes a couple of tries to get connected.

Proof of concept/testing for the Siccario Cinelifter