Blu3ness, people use radio wave triggers and receivers because it is more effective than the flash's built-in IR wireless. Using IR to trigger your flash can only work at a certain distance and can also sometimes be blocked, it isn't always reliable. Using a radio wave trigger and receiver such as a Cactus V4 uses radio waves, which are more effective, have a significantly longer range, and are far less prone to failing to trigger the flash. If you are going to be using wireless a lot then you should think about investing in one. Most people who extensively use wireless such as fashion, portrait, product photographers find these a necessity.
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