it is known that this focus system is performed manually in the action camera at the factory, the same thing happens on any FPV camera, where there is a ring to correct the focus.
I believe that the question here is more complex.
I am not a photography expert but I believe that the problem may instead lie within the group of lenses, which are obviously fixed inside the block that is rotated.
Even achieving perfect focus for a distant enough subject if the lens group is poorly designed will result in a wrong focus at the 30cm declared by DJI.
This is because classic infinity focus necessarily generates this problem, and more you want to have a ultra wide FOV, and the Osmo Action 3 has it, more you will have focus problems in close subjects.
In my OA3 for example the distant subjects are almost in focus, but those at 50 cm absolutely not, and DJI declares at least 30 cm.
Look at the weed in this video, with OA3 it looks poorly defined, with GoPro Hero 6 instead it is acceptable, considering that it is an action camera released in 2017.
Having said that I do not rule out that DJI has some lens groups, which for example should be 7 in the Osmo Action, not perfectly calibrated, badly designed or of very poor quality.
Therefore even by adjusting the ring by rotating it, the problem in close subjects may remain.
How is it resolved? With another well designed lens group and obviously at the correct distance from the sensor, so a firmware update cannot fix such a major hardware problem and perhaps unfortunately also by rotating the lens group.
In fact today many smartphones have more than one rear camera depending on the subject you want to shoot.
This is because the lens group is different depending on the FOV and the desired distance of the subject.
Unfortunately this action camera, like almost all the others, does not have a motorized lens system so the focus will always be a compromise.
So I'll wait for the new firmware, and sure enough that both software won't be able to fix it, I'll send my action camera to DJI to fix the problem.
If they declare "over 30 cm" a subject at 31cm must be perfectly in focus, as well as one at 20 meters.
