Hi @test.vtw welcome to the community 
Please read the similar post discussed here.
You should be using the bracket notation instead of dot notation.
For example,
let response=pm.response.json();
console.log(response);
pm.environment.set("camtest1", response['cam:test']);
pm.environment.set("camtest2", response['cam:test2']);
This is just based on the response you have provided above, please edit the path if needed 
I hope this helps!