Image Area: Choosing a Movie Crop
You can choose an image area using the  > [ ] item in the movie shooting menu. Select [ ] to shoot movies in what is referred to as “FX-based movie format”, [ ] to shoot in “DX-based movie format”. The differences between the two are illustrated below.
The sizes of the areas recorded are approximately 35.9 × 20.2 mm (FX-based movie format) and 23.5 × 13.2 mm (DX-based movie format). Movies shot with a DX-format lens and [ ] selected for [ ] > [ ] in the movie shooting menu are recorded in DX-based movie format.
Enabling electronic vibration reduction by selecting  for [ ] in the movie shooting menu reduces the size of the crop, slightly increasing the apparent focal length.