Digital SLR Photography All-in-One For Dummies, 4th Edition

Chapter 2

Setting the Aperture

IN THIS CHAPTER

Understanding f-numbers and apertures

Setting the aperture

Controlling depth of field

Being creative with depth of field

This chapter is about the aperture of your lens. You learn what an aperture is, how it affects exposure, how to tell what a lens is capable of, and how you can set the aperture. You also learn how the size of the aperture contributes to defining the scene's depth of field (the area in focus).

Armed with this information, you will have an understanding of what the aperture is doing when you use your camera's automated shooting modes, and if you like, take creative control and start setting the aperture yourself.

Investigating f-numbers and Apertures

The opening in every lens that lets light into the camera is called the aperture. Apertures shrink and grow by means of a mechanical iris. Larger apertures let in more light. Smaller apertures let in less light. The aperture plays an important part in exposure, and it’s expressed as an f-number, which I explain next.

An aperture is part of the lens, not the camera body. ...