Aperture uses for Depth of Field
- Aperture Affects Depth of Field
a large aperture results in a large amount of both foreground and background blur. This is often desirable for portraits, or general photos of objects where you want to isolate the subject. Sometimes you can frame your subject with foreground objects, which will also look blurred relative to the subject
a small aperture results in a small amount of background blur, which is typically ideal for some types of photography such as landscape and architecture. In the landscape photo, use a small aperture to ensure that both my foreground and background were as sharp as possible from front to back
Quick Note: The way the foreground and the background out-of-focus highlights are rendered by the lens in the above example is often referred to as “bokeh“. Although bokeh is the property of a lens, one can yield shallow depth of field with most lenses when using a large aperture and close camera to subject distance.
Ref - https://photographylife.com/what-is-aperture-in-photography