Aperture Mode

Part of my Photography series. May need to merge this with my Auto-Focus, Depth of Field and Aperture page. Also the Exposure Triangle.

The internet seems to say that Aperture mode is the most useful mode to work in. In this mode you control Aperture of the camera, while the camera controls the ISO and shutter speed.

Aperture control depth of field and how much of your scene is in focus.

What is Aperture

It’s the size of the hole in your lens that lets in light. Bigger means more light, smaller means less.

How is it measured?

It’s usually designated with a fraction like f/2 or f/16. This is the f-number, or the numerical aperture and the denominator is the relative aperture.

In any case, a small f-number means a smaller hole, less light, and a bigger denominator. A bigger f-number means a bigger hole, more light and a bigger denominator.

Effects of larger and smaller aperture

A smaller f-number means a smaller hole, and also means a bigger depth of field, which means that more of your image is in focus. A larger f-number means a bigger hole and also means a smaller depth of field, which means less of your image is in focus.

So, handy summary:

• bigger depth of focus means a bigger part of your photo is in focus, and is associated with a smaller f-number, or a bigger denominator. This is a narrow aperture.
• smaller depth of focus means a smaller part of the photo is in focus, and is associated with a bigger f-number or a smaller denominator. This is a wide aperture.

It’s really all about the denominator. It is directly related to the amount of your photo is in focus.

The Bokeh effect

The Bokeh effect is that effect where the subject is in focus and the background is blurry. This is associated with a small depth of field, i.e. a smaller denominator.

Other ways to affect your DOF

• distance to your subject
• focal length (i.e. your lens)

The wider your lens (smaller mm) the more DOF you will have for the same aperture. The tighter the lens, the less DOF you have (i.e. you’ll have a bokeh effect).

Also, the closer you are to your subject, the less DOF you have, for a given lens and aperture. Move closer to your subject and you can get a bokeh effect.