Its because of the Field of View (FOV).
An average human being can see about 45-60 degrees of vision (excluding peripheral vision).
But this game (and many others) set the standard FOV to 90 degree's so that we can use the keypad view system we use (and I also assume to simulate peripheral vision).
This is why things look too small.
When you "Zoom" in the game, your not actually zooming in at all, what its doing is changing your FOV back to 45 degrees, instead of 90 degrees.
Which is why things look "right" in zoom mode, but too small in normal mode.
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Vermillion
**MOL**, Men of Leisure
"Real Men fly Radials, Nancy Boys fly Spitfires"