Visual Correction for Long-Sightedness
- People who are long sighted → unable to clearly see objects close to their eyes
- Their eyes focus the rays from each object point to a point beyond the retina (above image)
- As light rays → not focused on retina → rays from a single object point form an extended patch instead of a sharply focused point on the retina.
- when diff object points form many overlapping patches on the retina → overall image becomes unclear.
By wearing spectacles with suitable converging lenses → image focal points can be brought onto retina to form sharp image.
Forming Image in a Camera
Converging lens → used to form an inverted, real and diminished image → on a sensor of a film camera.
- Focusing ring is used to adjust lens to sensor distance.
→ minimum distance between the lens and sensor (i.e. focal length F) → faraway objects will form sharp images on the sensor.
→ As lens is moved further out → nearer objects become more focused.