Image Characteristics

An essential framework for analyzing images formed by lenses and mirrors: Nature, Size, Orientation, and Position.

The Four Pillars

When an optical instrument like a lens or mirror forms an image, we describe it using four key properties. Mastering these helps predict and understand the behavior of light.

Nature
Size
Orientation
Position

1. Nature

Real

Formed by the actual intersection of light rays. It can be projected onto a screen.

Virtual

Formed where rays appear to diverge from. It cannot be projected.

2. Orientation

Upright

Same orientation as the object.

Inverted

Upside-down relative to the object.

3. Size (Magnification)

The ratio of the image height to the object height. It can be magnified, diminished, or the same size.

Object

2x

MAGNIFIED

Image

4. Position

Where the image is formed, which depends on the object's distance from the lens/mirror and its focal length (ƒ).

Convex Lens Summary

How image characteristics change with object position.

Object Position

Image Position

Nature

Size

Orientation

Beyond 2ƒ

Between ƒ' & 2ƒ'

Real

Diminished

Inverted

At 2ƒ

At 2ƒ'

Real

Same Size

Inverted

Between ƒ & 2ƒ

Beyond 2ƒ'

Real

Magnified

Inverted

At ƒ

At Infinity

Real

—

Between Lens & ƒ

Same side as object

Virtual

Magnified

Upright