纪录片作为一种纪实艺术,真实性是其产生艺术魅力的根源。而长镜头作为影视创造的一种理念和手法可以极大地增强纪录片作品的真实性品质,因此,在纪录片的实际拍摄和创作中,使用长镜头可以创立作品的真实感已经成为众多纪录片创作者的共识,但如何正确地使用长镜头特别是设置长镜头的时长,至今还没有一个相对明确的规定。论文试从微观的视角和发散性思维出发,结合三部纪录片作品当中出现的长镜头进行分析和论述,一方面在长镜头和蒙太奇的相互比较中对长镜头的概念进行了相对界定,旨在说明时长只是长镜头的外化特征,而非长镜头的本质和时长是形成长镜头的必要条件而非充分条件;另一方面着重提出了设置长镜头时长的三方依据,即镜头提供的“有效信息”的数量、“一般受众”对信息的解读时间、受众情感的延续性。 Documentary as a documentary art, authenticity is the root of its artistic charm. The concept of long shot as a film and television to create a concept and approach can greatly enhance the authenticity of the documentary works, so the actual shooting and creation of the documentary, the use of long shots to create the work of the realism has become the documentary creator of many Consensus, but how to properly use long shots, especially the length of time to set the lens, so far there is no relatively clear rules. Based on the microscopic perspectives and divergent thinking, this dissertation analyzes and discusses the long shots appearing in the three documentary works. On the one hand, the concept of long shot is defined in the mutual comparison of long shot and montage, It shows that the length of time is only the externalized feature of the long shot, but the nature and duration of the non-long shot is not a necessary condition for the formation of a long shot. On the other hand, the author puts forward the tripartite basis for setting the length of a long shot, Effective information “, ” general audience "time to interpret the information, the continuity of the emotional audience.