We have been testing a lot, both with Android and iOS devices to find the best work around for unsharp pictures with a Mavic Pro ( v01.04.0100 ) and Pix4Dcapture. All firmware and software versions are up to date as of this post.
We used the generally recommended work around to first set the camera in focus in the DJI Go 4 App ( v4.1.18 ) and then switch to Pix4Dcapture. Additionally, we tried Litchi ( iOS v2.0.0, Android v4.0.2 ) replacing the Go 4 App.
1) Using Apple iPad 4 Mini ( iOS v11.2.1 ) with Pix4Dcapture ( v2.8.0 )
This combination gave very unreliable results, but most of the time the camera would reset to out of focus after uploading and starting the mission. Trying all sorts of combinations of autofocus/manual focus, Litchi vs. Go 4, unplugging and replugging did not result in a reliable work around.
The few times we managed to get sharp pictures, was only with single grid missions and was never successful with double grid missions.
–> Main observation: Pix4Dcapture in the iOS version hijacks the camera settings when starting the mission resulting in overriding the previously focused camera settings. Even within Pix4Dcapture the camera view shows sharp pictures prior to starting the app.
–> Our recommendation to Pix4D: Give the user an option that allows/disallows the app to change the camera settings.
2) Using a Samsung Galaxy S7 ( Android 7.0 ) with Pix4Dcapture ( v4.0.1 )
Using the workaround as described above results in sharp pictures every time we tried, for both single and double grid missions.
–> The problem: Switching apps on Android is much more complicated, error prone and much less reliable than on iOS. Specifically, even if executed correctly Pix4Dcapture might not connect to the drone after using Go 4 or Litchi.
–> Our recommendation to Pix4D: Take a look into why Litchi and Go 4 can easily be loaded at the same time, switched in between and connect to the drone, but Pix4Dcapture cannot.
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Our solution, that works 100% of the time: We use two devices: One to set the camera in focus, in our case the iPad, and the other (must be an Android device) to execute the mission. However cumbersome that might be, it is very reliable and doesn’t cost valuable flight time.
Additionally, we set the camera in focus to a distant point while the drone is still on the ground and the motors aren’t armed. This way we safe some more battery and the pictures are sharp enough for the purpose of mapping.
Please let me know, if you have any questions about the above or if something is unclear