The ASPECT ratio is set from the REC Setup menu (the
camera icon tab). This sets the height and width ratio of
your image.
If you are shooting images primarily for prints then for 4 x 6
inch prints (and its multiples 8 x 12 etc) then select 3:2
For other sizes 4:3 may be selected bearing in mind some
common print sizes like 5 x 7 inch will require some
cropping of the final image.
If you intend to use the images for HD video or display
without borders on your HD aspect TV select the 16:9 option
from this menu.
Each of these aspect ratios will display the actual image area
that you have selected on the LCD display or electronic
viewfinder (EVF).