After the clip is captured or imported into Final Cut, take it from the Browser and drag it into the Timeline, which will make it easier to work with. Place it where you want it to be in the sequence and then double click it, bringing it into the Viewer.
Go back to the Browser and click on the Effects tab, which should be right behind your project’s tab unless you have multiple projects open. Either way it will always be the tab that is the farthest back.
Once there click on the Video Filters folder, which then opens into a series of sub-options. These sub-options range from Blur to Stylize and are all series of video effects that you can apply to your video.
Click on the option labeled Image Control, and again you will be given a list of sub-options below it.
Go to the one titled Desaturate and drag this option onto the image in the Viewer. Suddenly your image will appear in black and white!