conventions

In Documentaries you often find a various amount of conventions.
In a documentary it often starts with a voice over it is usually someone with an authoritative voice so it draws people in, this is encouraging to the audience to think that the person who is doing the voice over knows what they are talking about and have a specialist knowledge. There speech should be articulated clearly so that you can understand clearly.
Documentary is essentially seen as non-fiction although people are questioning this. However, a convention of a documentary is that all events presented to us are to be seen as real by the audience. Documentaries often go to a great lengths to convince us that the footage is real and unaltered in anyway, although editing and
voiceover can effect the reality of what the viewers see.

When it comes to documentaries you often see footage of situations that have happened in the past for example we watched a documentary called 'Touching the Void' this was a documentary about how two men climbed up Suila Grande mountain the footage used was re-enacted for the film as they had no archive footage.
In documentaries you often find that they have interviews with people who know about what they are talking about and they have a lot of experience in the area that they are talking about, sometimes you will find that the interviewee will disagree with the message of the documentary, although the film maker will usually disprove them in some way.
Text is often used so that the audience can keep up with the programme for example; if the place was to change they could put text at the bottom showing the name of the place that they are now at, it can range from the time of day to the date showing if there has been a change in something since that day.

In a documentary there is often a lot of sound used to show a mood or action of a person that is often called non-digetic sound, for example in the documentary 'Supersize me' the use of children's music that they use is how they undermine McDonalds to prove the point.

Conclusion

The difference between News and Documentary is you find that in news it is set up and they have a script so that they can show facts. However with documentaries you find that they are planned but not scripted, they are given a topic and broaden it and use facts too.
In fact documentaries are very similar to the news due to the fact they have to document things that are going on in the world and the documentaries are just a longer more detailed version of a news report but could be based on things that aren't as important as the problems on the news.