1.
Easier to see the subject in bright sunlight.
2.
Easier to hold the camera steady.
Your head is steadier than two outstretched arms.
3.
DSLR cameras can display exposure data right under the optical view in the viewfinder.
Very helpful with difficult lighting conditions.
4.
Easier to follow the action when shooting sports or panning the camera.
Why do people use the viewfinder more than the screen?

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