The three styles of filming interviews are Observational in which are people recorded during answering on questione they heard or they are just talk about something with no presenter or narrator but it has voice over also everysingle person is filmed by rule of thirds. Expository also voice over and many kind of shots like in observational like mid-shot, long shot and both are non-intrusive but is using also something what is called Nose, Head and Hand room where some spaces have to be cutted or avoided during recording like space above head or hold hands to do not break the recording image and Nose room which have to guide from which position head could be recorded to get right effect. Participatory is kind of documentary which had most of thing which never exist in
Expository or Observational and that is Narrator or Presenter which go everywhere with camera man and meet many people and ask them questions which most audience want to ask. Also in this documentary Presenter gain answers and also show his own responses on how people behave around like he can be affraid or something can make him/her laugh or cry. And only that kind of documentary can show noddies. Whole different between them three is not big it's just in few different techniques they are use like in one you can see mid-shots and long shots in other we can find noddies in another just talking people with voice over. All that stuff change audience vision for documentary depends what that documentary has to share with audience then is choosing best style. Personaly I like them all, it's really nice and easy to watch.
