Multiple choice general knowledge science & technology

Why does one sometimes have red-eyes in photographs?

  1. The rays of the sun bounce off the lens of the camera, projecting a reddish glow into the eyes of those photographed.

  2. An ineffective flash doesn't allow enough light for the actual eye color to be recorded in the photo.

  3. A flash that is too glaring often makes people blink at the same time the shutter snaps. Therefore, the subjects eyes are merely blurred, though it appears red in the actual photo.

  4. The pupil doesn't have enough time to constrict and the picture records the reflection of the red retina in the back of the eye.

  5. I don't know
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The red-eye effect occurs because the camera flash is too fast for the pupil to constrict. The light enters the dilated pupil, illuminates the retina (which is rich in blood vessels and appears red), and reflects back to the camera. The other options are incorrect - sun rays aren't relevant, flash effectiveness isn't the issue, and blinking causes blur, not red-eye. Option E is not the scientific explanation.

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