1. Camera angle – Generally you will dissolve between two shots that present differing camera angles on the action, either from footage within the same scene or from two adjacent scenes in the story. Sometimes you may need to collapse time for one long, continuous event recorded from the same angle. Consider the following example – a bank robber is “trapped” in his hideout waiting for his partner to arrive. The scene encompasses time from late afternoon to late evening with appropriate lighting changes throughout. It is all shot from only one stationary camera angle. To compress time, and quickly show the escalating agitation of the man, the editor dissolves between short portions of footage. From daylight through drawn shades to dim desk lamp, the audience gets to watch the character move around the room, sit down, lie down, check his phone, peek out the window, etc. – all over elapsed “film time” via these multiple dissolves.
2. Sound – It is customary to also mix together the audio tracks of the two shots being dissolved in what is often called an audio cross fade. As the picture for shot one is dissolving away gradually under the incoming image of shot two, the audio tracks for shot one are also fading down (growing quieter) while the audio for shot two is fading up (growing louder).
3. Time – An important element in the efficacy of the dissolve is its duration, or how long it lingers on screen. One second is usually the default duration for dissolves in video editing software, but a dissolve can last for as long as there is visual material in each shot involved in the transition. In general, the dissolve should last as long as is required for its purpose in the motion picture. A quick dissolve of just a few overlapping frames, sometimes referred to as a “soft cut,” might be preferable to an instantaneous straight cut – but beware that this can imitate a jump cut. A long dissolve can be on screen for several seconds and may, along the midpoint of this longer duration, appear more like a superimposition of the two shots rather than a dissolve. If the story calls for such a visual treatment of these two images uniting for this longer period, then so be it.
4. The dissolve allows the editor to play with time. If you were editing a story that involved a flashback, you could dissolve from the last shot of the present time to the first shot of the events from the past. Also, the dissolve is often used to create a montage of many different images that condenses events over time; for example, a day at the amusement park is shown through ten shots that dissolve from one to the next, the whole sequence lasting only thirty seconds of screen time. Usually such special treatments of visual material are planned by the filmmakers from the outset of the project, but editors should feel free to experiment with dissolving time if they find certain scenes to be too long.
It is important to note that dissolves can also slow down time and manipulate the emotions of an audience when accompanied by slow motion imagery. A romantic or maybe an emotionally sad sequence can use dissolves rather effectively to slow down events and give the audience time to view and digest the meaning of the material. The gradual transition from image to image softens the experience. It is said that dissolves are the “tear jerker” transition. They allow the viewer time to think and feel, they are associated with more languid, somber, or “thoughtful” emotional responses to the visual story elements.
Dissolves can be used in any time-based motion media piece such as fictional narrative movies, television shows, music videos, documentaries, animated cartoons, how-to and wedding videos, and so forth. There was a time that you would have been hard pressed to find dissolves in the daily news, but even factual reporting has incorporated the “manipulative” transition. An indication of how the rules of visual grammar are changing with our never-ending 24-hour mobile access to motion media.