Panasonic TX-26LX1F Operating Instructions Manual page 20

Aspect Controls
Zoom1
Zoom1 will display 16:9 letterbox or 4:3 pictures with no aspect
distortions.
Zoom2
Zoom2 will display 16:9 anamorphic letterbox pictures as a full screen
display with no aspect distortions.
Zoom3
Zoom3 will display 21:9 letterbox pictures as a full screen display with
no aspect distortions.
16:9 will display the picture at its maximum size but with sligth stretching.
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Zoom1
Zoom1
Zoom2
Zoom2
Zoom3
Zoom3