Which statement correctly describes retinal image size as distance to the observer changes?

Which statement correctly describes retinal image size as distance to the observer changes?

• A. The nearer the object, the larger its retinal image.
• B. The farther the object, the larger its retinal image.
• C. Retinal image size is independent of distance.
• D. Retinal image size remains constant with distance.

Answer: (A)

The retinal image size is determined by how large an angle the object subtends at the eye. When an object is close, it covers a larger angle in your field of view, so it creates a larger image on the retina. As the object moves farther away, the angle it subtends becomes smaller, producing a smaller retinal image. For a fixed physical size, the retinal image size is roughly inversely proportional to distance. That’s why near objects look larger on the retina, while distant ones look smaller. Statements that retinal image size is independent of distance or that it grows as distance increases don’t fit the geometry of how the eye forms images.

The retinal image size is determined by how large an angle the object subtends at the eye. When an object is close, it covers a larger angle in your field of view, so it creates a larger image on the retina. As the object moves farther away, the angle it subtends becomes smaller, producing a smaller retinal image. For a fixed physical size, the retinal image size is roughly inversely proportional to distance. That’s why near objects look larger on the retina, while distant ones look smaller. Statements that retinal image size is independent of distance or that it grows as distance increases don’t fit the geometry of how the eye forms images.