Lecture Notes on Aperture in Photography

What is Aperture?

• Aperture is the hole in the lens through which light travels into the camera body and onto the camera sensor.
• Analogous to the human eye:
  • The cornea gathers light.
  • The pupil acts as the aperture.
• Larger aperture (larger pupil) allows more light into the camera.

Control of Aperture

• The iris of the lens controls the size of the aperture, also known as the diaphragm.
• Aperture is expressed in f-numbers (f-stops):
  • Smaller f-stop = Larger aperture
  • Larger f-stop = Smaller aperture
  • Example: f/1.4 (larger) vs. f/2.8 vs. f/8 (smaller)

Impact on Depth of Field

• Depth of field: the area of the image that appears sharp.
• Larger f-number (e.g., f/16): brings both foreground and background into focus.
• Smaller f-number (e.g., f/1.4): isolates either the foreground or background and blurs the rest.

Lens Specifications

• Each lens has a maximum and minimum aperture:
  • Maximum aperture: more important, indicates lens speed (e.g., f/1.4 or f/2.8 = fast lenses).
  • Minimum aperture: usually not as significant; diffraction can cause loss of clarity.

Types of Lenses

1. Prime Lenses
   • Fixed focal length; cannot zoom.
   • Have a fixed maximum aperture.
2. Zoom Lenses
   • Variable focal lengths (e.g., 70 to 200 mm).
   • Maximum aperture often decreases with increasing focal length (e.g., f/3.5 to f/5.6).

Relation to Other Camera Settings

• Aperture influences ISO and shutter speed:
  • Larger apertures = more light = faster shutter speed or lower ISO.
  • Useful for reducing motion blur and noise in images.
• Important for:
  • Nighttime photography (requires fast lenses).
  • High-speed photography.

Camera Modes

• Aperture Priority Mode: Change aperture while the camera automatically adjusts shutter speed and ISO.
• Manual Mode: Full control over ISO, aperture, and shutter speed.

Conclusion

• Aperture is a critical and stylistic setting that can create unique effects in photography.