AVCHD are the most popular format for camcorders such as Canon, JVC, Panasonic, Sony, Hitachi, Leica Camera, etc. But for some Mac users, they don’t know how to edit AVCHD with FCE. Now I will recommend a tool for you to resolve that

Application for editing AVCHD with FCE
Apple's powerful moviemaking application--Final Cut Express 4, supports AVCHD-based tapeless camcorders and enables people to edit footage captured in the most popular formats--AVCHD. Mac AVCHD to MP4 Converter Simply connect your camcorder to your Mac, select the AVCHD clips you would like to import, and start editing your video.

However, due to the wide range of camcorder types and different ways manufacturers store video on these camcorders, not all tapeless camcorders work with Final Cut Express
import avchd to iMovie

4. The compatible camcorders are listed in: http://support.apple.com/kb/HT2948#tapeless. When imported to Final Cut Express, the incompatible camcorders usually have the following problem: device not recognized, not displaying imported specific device or the imported specific device is not available to be viewed or edited.

AVCHD to Final Cut Express 4 is the fantastic conversion software provided for Mac users to convert Sony, Canon, Panasonic camcorder AVCHD(MTS/M2TS) to Final Cut Express well supportable MP4, MOV, MPG, MPEG, DV format with super-fast conversion speed and best output quality.