This opening sequence is for the first saw film, which was released in 2004. It is very effective for the audience as it sets the mood for the rest of the film. The lighting is dark creating a sense of mystery about what is happening as we can't see where the characters are or what is happening to them, this also means that the scene is likely to be jumpy as in most horror films traditionally when it is dark and you can't see much something jumps out the screen and scares the audience. The camera focuses on the key with the light falling down the plug hole highlighting the importance of it and that it could've been used by the prisoners to help them escape. When the man wakes up and gets out of he bath a voice can be heard talking to him, but the audience cannot see who it is, again creating a mysterious feeling around what is going on. When the lights flash on the camera changes to the characters view and it goes out of focus and back into focus to show that he is adapting to the light, suggesting he has been in the dark for a long time and his kidnapping happened some time earlier.
Only four titles are shown in this opening sequence, these are the two production companies (Twisted pictures and Burg/Koules/Hoffman) after these it shows the directors title (James Wan) and finally it shows the film name (Saw). By just showing these titles it makes it short and sweet and then breaks straight into the film, for some audiences this would be better as they prefer just watching the film rather than seeing who is in it, but some audiences like to see who is playing the characters. So only having some titles has benefits and positives.