Back to topics

Aperture and the range that looks sharp

In some portrait photographs, the person's face is tack-sharp while the background melts into a soft blur; in landscape shots, everything from a nearby rock to a distant mountain looks crisp. Changing the lens aperture, the size of the opening that lets light into the camera, controls this 'depth of field,' trading light gathering against the range of distances that appear in focus.

4–5 min

Questions you could explore

  • Why is 'acceptably sharp' different from a single perfect focus distance?
  • What trade-offs appear when the aperture becomes very small?

Start reading

  • Canon EuropeAperture

    Canon explains aperture and depth of field, including comparison images; it is a manufacturer’s educational account, not a camera ranking.

Ready to try your ideas aloud?

Your topic carries over. Record up to 2½ minutes, depending on your plan.

Arts and culture

How does perspective make a flat drawing look three-dimensional?

A drawing lies on a nearly flat surface, yet a few carefully angled lines can make it look like a long hallway stretching into the distance. In one-point perspective, receding parallel edges converge toward a single vanishing point on a horizon line, linking the flat drawing to a particular viewer's eye level.

3–5 min

How does perspective make a flat drawing look three-dimensional?

Arts and culture3–5 minA drawing lies on a nearly flat surface, yet a few carefully angled lines can make it look like a long hallway stretching into the distance. In one-point perspective, receding parallel edges converge toward a single vanishing point on a horizon line, linking the flat drawing to a particular viewer's eye level.

Arts and culture

Looking beneath a painting with infrared

The finished surface of an oil painting is not always the first version the artist drew on the panel. Because certain paint layers allow infrared light to pass through while carbon-based charcoal or ink absorbs it, infrared imaging can reveal hidden underdrawings and abandoned ideas beneath the visible masterpiece.

4–5 min

Looking beneath a painting with infrared

Arts and culture4–5 minThe finished surface of an oil painting is not always the first version the artist drew on the panel. Because certain paint layers allow infrared light to pass through while carbon-based charcoal or ink absorbs it, infrared imaging can reveal hidden underdrawings and abandoned ideas beneath the visible masterpiece.

Can a tradition be heritage without a building to preserve?

Arts and culture3–5 minA song, a craft skill, or a shared practice can be passed on without being fixed in stone. Intangible cultural heritage places importance on living knowledge and the communities that recognize and transmit it.

Aperture and the range that looks sharp | Speech Topic | speaking.app