Apple Final Cut Pro 7 - Manual (Page 1777)

In this mode, the video track is cropped to the Clean aperture mode and scaled according
to the track’s pixel aspect ratio. For example, a 4:3 DV NTSC track appears as 640 x 480;
a 16:9 DV NTSC track appears as 853 x 480.
Clean: pixel aspect ratio
correction applied and
edges cropped
Production Aperture Mode
Content may appear differently than in QuickTime 7. The video track is not cropped to
the Clean aperture mode, but it is scaled according to the pixel aspect ratio. Use this
option when you want to see all the pixels in your video, including the edges. A 4:3 DV
NTSC track appears as 654 x 480; a 16:9 DV NTSC track appears as 873 x 480. Compare
this to the Clean aperture mode, which crops the edge-encoding pixels on the left and
right.
Production: pixel aspect
ratio correction applied
with no edge cropping
1777 Chapter 106 Exporting Using QuickTime Conversion