Focal Length Determines:

Image Size
Angle of View

Short Focal Length - SMALL Image Size - WIDE Angle of View (aka "Wide-Angle" Lens) 12 millimeter

Medium Focal Length - NORMAL Image Size - NORMAL Angle of View (aka "normal" lens) 25 millimeter

Long Focal Length - LARGE Image Size - NARROW Angle of View (aka "Long" Lens) 70 millimeter

*** NOTE:
In still cameras, "normal" is about 50 mm.
In video and 16mm film, the values are cut in half due to different "target sizes."

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