Making cheap Pan+Tilt servo bracket mount work with heavy camera
I am talking about these cheap servo brackt mounts on aliexpress:
https://www.aliexpress.com/w/wholesale-Servo-Mount-Pan%252FTilt-Camera-Platform.html
There is no problem mounting lightweight cameras like Raspberry v1/v2/v3 cameras in intended direction.
I added 55g Arducam PTZ camera in that direction with a first adapter:
https://forums.raspberrypi.com/viewtopic.php?t=347704#p2083481 
While that worked, it was a bit unstable.
RE: Making cheap Pan+Tilt servo bracket mount work with heavy camera
Next I modified the adapter to mount the PTZ camera the other way around in order to bring center of mass more over rotation center.
This worked surprisingly well, despite the fact that base of camera holder was not fixated to ground in any way:
I published model on printables.com, most important is OpenSCAD script.
The left part including the long hole is for snapping into camera holder.
The right part is for Arducam PTZ camera, the small hole and big center hole are needed for adapter solder points.
You can just replace the right side with anything needed to connect your heavy camera:
https://www.printables.com/model/405720-adapter-to-make-cheap-pantilt-servo-bracket-mount- 
RE:
When looking far up system became unstable even with new bracket adapeter.
So I 3Dprinted a 80mm diameter base plate onto which the cheap camera bracket base can be screwed, with its provided 2mm diameter screws:
https://www.printables.com/model/406859-base-plate-for-cheap-pantilt-servo-bracket-mount-w 
I used digital camera to record PTZ camera with camera holder, and HDMI display in background showing live camera view. It starts far up showing 92cm diameter C60 fullerene hanging 3m high, zooms out with adjusting focus, goes down to see its base plate, turns to wall and goes up again to show analog clock from last night:
This is corresponding video captured with PTZ camera: