Depends. The 4th amendment protects people, not places.
For your house?
Probably
For your yard?
Probably not, but it depends what part of the yard.
Cameras arranged on poles?
I'm too lazy to look up cases.
See Kyllo and friends.
The reason it's divorced from "freedom from observation" is because the constitution does not guarantee you a freedom from observation, only a freedom from search.
These are not the same.
As one of the cases says, "the police are not required to shield their eyes as they pass homes if they do not have probable cause"
Would you have protection from guvmint agents on stilts? I'm not being snarky; this is going somewhere.
What about cameras arranged on poles, aimed at backyards, with ubiquitous deployment?
It's a shame that this "no expectation of privacy" stuff is divorced from "a freedom from observation" (which is really what we're talking about).