What Is a Convex Lens? 

What Is a Convex Lens featured photo

Do you ever wonder how a camera captures light and brings distant objects near? It uses a type of optical lens to make far objects appear larger and closer than they actually are. This lens is called a convex lens.

A convex lens has a curved surface that bulges outwards in the center. It causes passing light rays to converge at a single focal point beyond the lens. It ultimately lets you see a focused image.

Convex lenses have many uses in our daily lives, as we will show you below. This article also covers the other lens types based on their shape. But first, let us teach you the definition and features of a convex lens.

What Is a Convex Lens?

A Convex Lens

Also known as a converging lens, a convex lens has a bulging outward shape. It typically has a spherical surface, but it can also be parabolic or elliptical.

A convex lens has thicker glass or plastic material in the middle than the edges. It causes light rays passing through the lens to bend inward and converge or meet at a focal point. This area is located on the opposite side of the lens where the light rays emerge. Meanwhile, the focal length is the distance between the lens surface and the focal point. 

Convex lenses make distant objects appear larger and closer than they are because they refract light. They focus this light beam on a single point beyond the glass or plastic focal elements. Hence, they let you see and recognize various objects from afar.

What Are Convex Lenses Made Of? 

Convex lenses typically use glass or transparent plastic for their construction. The type of material you choose depends on your intended application and the required optical properties of the lens.

Most convex lenses are made of glass. This material offers durability and excellent optical clarity. 

However, plastic convex lenses are also available. These are cheaper, lighter, and more flexible, which makes them suitable for various applications.

Some specialized convex lenses common in laser systems use transparent crystals like quartz or sapphire. These have unique optical properties that meet specialist needs.

What Are the Uses of A Convex Lens?

A convex lens has many uses in our daily lives.

The prime example of this lens is the human eyes. It bends lights and creates a focused image on the retina at the back of our eyes. It ultimately helps us see.

Another popular use of a convex lens is in eyeglasses. It can correct hypermetropia or farsightedness (long-sightedness) by letting light rays converge and focus on the retina.

A convex lens is also the type of lens found in a magnifying glass. It delivers an enlarged image of an object when placed at a shorter distance than the lens’ focal length.

Plus, convex lenses are essential to the construction of microscopes. They produce an erect and magnified image. When stacked together, they let you see objects at a high magnification rate ranging from 40x to 1000x.

Convex lenses are even used in cameras. They focus light on an image and magnify it to create high-quality results.

Other common uses of a convex lens include binoculars, telescopes, projectors, and laser systems. 

What Type of Image Is Formed by Convex Lens?

A convex lens can create either a real or virtual image, depending on the object’s position.

A convex lens forms a physical photo when you place the object beyond the focal point. It depicts an erect and magnified picture.

However, when you position an object between the lens and the focal point, the image formed is a virtual one. It is upright and prevents you from projecting it onto a screen.

What Is the Focal Length of a Convex Lens?

The focal length of a convex lens describes the gap between the optical middle and its focal point. As previously mentioned, the focal point is the area where light rays converge after entering the lens.

The focal length determines the size of the image the lens creates. When you place objects at a greater distance than the focal length, it forms a real and inverted photo. However, it produces a virtual, upright image when the subject is located at a distance less than the focal length. 

The focal length is a fixed feature of the lens. It is usually indicated on the lens barrel itself. 

What Are the Other Types of Lenses?

Optical lenses come in two main lens types, depending on their shape and purpose. Let us cover them in detail below. 

Concave Lenses

A concave lens is the opposite of a convex lens. It has a curved surface that bulges inward rather than outward. So instead of making light rays meet at a single focal point, this lens type causes light to diverge or spread out.

A concave lens forms images that appear like they come from an area, or focal point, behind the lens. But since it is not real, it is called a virtual focal point.

Concave lenses are essential in eyeglasses to correct myopia or nearsightedness. They are also suitable for cameras, flashlights, lasers, peepholes, and projectors.

Compound Lenses

As its name suggests, a compound lens combines both convex and concave lens elements. Or it can also have a double convex lens construction. Either way, it has two or more lenses mounted on each other to correct optical aberrations.

Compound lenses can be used on more advanced microscopes and telescopes. They are also ideal for camera lenses.

Adjustable Lenses

A standard convex or concave lens has a fixed focal length. Fortunately, another type of lens known as an adjustable lens is available. It offers a variable focal length that can make subjects seem closer or farther away.

In photography, this type of lens is known as a zoom. It features multiple lenses that move together or apart, depending on how you turn the zoom ring. 

Adjustable binoculars and telescopes with adjustable lenses work the same way. But instead of a zoom ring, they have a focusing screw. This part allows you to move the lenses closer to each other or further apart.


Photographers can capture distant objects and make them appear larger with a convex lens.

Also known as a converging lens, it has a curved surface that bends outwards. It can make light rays meet or converge at a single focal point beyond the convex lens. It is suitable for various applications, as we explored in this article. 

Do you have other questions about convex lenses? Feel free to drop by our contact page and send your queries.