Do flies have good eyesight?
Flies do not have eyesight like humans. Flies have compound eyes (many tiny eyes). Fly eyes are very good at detecting movement and colors, but not good at detecting shapes. Flies search for food by smell not sight, so identifying objects is NOT important, detecting a fly swatter IS important.
Flies have rod and cone compound eyes, like many other insects. Is this good enough to say read a book? No but, their eyes allow them to see a large area around them, including behind them, so they can evade capture or being swatted by a fly swatter.