I have identified the part(s) that are causing the camera to change focus. Any "deployed" module, science, hab 2 or greenhouse. I made some very basic craft and then eliminated possibilities. They can be unmanned and un-mechjebbed, with or without any other modules. As soon as you deploy the module, the camera focus will shift from any new modules that come within 2.5km. I moved a module off the runway at ksp. Launched a new module. Toggled over to the first one, quickly deployed and toggled back. Once the module had fully deployed, camera focus changed. Toggle back to the deployed module, retract, toggle back to the new launched module and focus remains. I tried all these scenarios with and without the hub. The hub makes no difference. Hope this helps!