Legal Question in Landlord & Tenant Law in California

No, although it is a good idea. Any audio recording of private conversations without the consent of all involved is a crime. Video is a little different. If you don't use any enhancement, such as a zoom lens, infrared, low light, etc., video and still photography is legal without consent (what you do with the images may be subject to other laws). Also, whether audio or video there must be a reasonable expectation of privacy before any of these laws apply. So that's why it's a good idea. If people are on notice of any kind of surveillance, they can't expect privacy.