...now you need to find one particular camera out of the hundreds or thousands slaved to the host....
Either you rule that it is
immediately obvious (because you automatically spot icons you have User or Admin access on and the camera is not trying to hide from you anyway) and you just take your action on the specific camera without requiring any test or action economy in order to first spot it.
Or you resolve it with a matrix perception test (because finding an obvious thing with your regular perception, like a neon sign, might perhaps require a test... at least in situations where there might be hundreds or even thousands of different neon signs in your field of vision).
...or find a particular file
To find a specific File in this edition you use the Hash Check action (SR6 p. 182).
If you already know the hash value of the specific File Icon you are looking for then the threshold to find which 32 likely candidates is 1, otherwise (like if you are looking for backup footage of a surveillance camera) the threshold is 4. For each extra hit you can divide the number of candidates by 2 (to only end up with one single candidate you need a total of 5 net hits). You can also add more hits by Trying Again. Each attempt cost one Major Action.
(For reference; in previous edition there was no Hash Check action.... instead you used the Matrix Search action, but with a base time of 60 seconds).