When choosing lenses for landscape photography, we usually want to see as much detail as possible from foreground to background we want to achieve the maximum depth of field by choosing a small aperture (higher f/stop, like f/8 or f/11).
This helps direct the viewer's attention to the subject. But it does also do something positive for youthat narrower aperture gives your image a broader depth of field. That smaller hole lets in less light, which limits your ability to shoot in low light conditions. Aperture for Portraitsįor classic portraiture we separate our subject from the surroundings by using "selective focus." Choosing a large aperture (lower f/stop, like f2.8) creates very shallow depth of field with only the subject, or just a portion of the subject, in focus. To summarise, it is important to understand that wide aperture pertains to a large opening but when measured in f-stops, it is displayed with a small number. When you select a narrow aperture, you are choosing to make the hole between your lens and your image sensor smaller.
Now that we know how to control depth of field, what determines the choices we make in selecting the aperture? We use focus and depth of field to direct attention to what is important in the photograph, and we use lack of focus to minimize distractions that cannot be eliminated from the composition. While there are no rules, there are some guidelines for selecting Aperture priority. In most areas of optics, and especially in microscopy, the numerical aperture of an optical system such as an objective lens is defined by, where n is the index of refraction of the medium in which the lens is working (1.00 for air, 1.33 for pure water, and typically 1.52 for immersion oil see also list of refractive indices), and is the maximal half-angle of the cone of light that. If youre learning about photography, use a small aperture (large number like f/16) if you want most things in focus.