You see a photo that you love, it has that trademark beautiful soft background you've been yearning to get in your own images. Problem is, you have no idea how to achieve this look. This can be achieved by understanding your camera's aperture. As we previously talked about, aperture is part of the exposure triangle as one of the key elements which controls what your end product will look like. Let's dive in and fully understand just what aperture is.
Aperture is that hole in your lens that allows light into your camera's body, ultimately hitting the sensor where your image is recorded. All lenses will have an aperture value assigned to them. This number can either vary or stay constant. When you see a lens listed it will say for example, "24-70mm f2.8." The f2.8 corresponds to the aperture value. Since this number is constant this means that this is the maximum aperture value from 24mm all the way to 70mm. However some lenses will be listed with values such as, "18-135mm f3.5-5.6."This means that at 18mm this lens' maximum aperture is f3.5, but when you zoom further in this number increases and eventually will have a maximum aperture of f5.6 at 135mm. This is due to lens quality/build. A lot of optics physics could be used to explain this, in short just know that the lens is much lighter and cheaper to make this way. The lower the maximum aperture value, the more light the lens can allow in and therefore will be heavier and higher quality (typically). Now it is not necessary to always have the highest quality lens. This will come down to what you are shooting and what you are trying to portray.
The most important aspect to understand is that the smaller the f value the more light that is allowed in and in turn less depth of field. This also means the higher than f value the less light that is allowed in and more depth of field is achieved. The more depth of field, the more of the image that is in focus. Let's look at some practical examples.
Take example the image above. I shot this image at f2.8, or "wide open."You'll notice the small depth of field in the image which is what we perceive as that soft background look known as bokeh. This is also partially due to how far the subject is separated from the objects behind it. When an object has a lot of distance behind it before another object appears, this effect also becomes prevalent. Most common uses of wide open aperture are: portraits, macro photography, sports photography, & astro photography.
Above is an image I shot at what is considered 'the sweet spot' on most lenses, f8. This is often the sharpest aperture value on most lenses. This offers adequate depth of field while avoiding what we call diffraction (will talk about in the next paragraph). As you can see more of the image is in focus and it is much sharper than the image shot at f2.8. There is a saying in photography, "f8 and be there." This relates to event photography and how as long as you shoot at f8 and are there, your images will turn out just fine. Best uses of aperture range f5.6-11: events, landscapes, lifestyle, architecture.
Lastly we have an image I shot at f22, the highest f value my lens offers. You'll notice that the depth of field seemingly lasts the entirety of the image. However this comes with back draws as well. As mentioned above after about f11 you will experience what is known as diffraction. Diffraction causes images to be less sharp as light is forced to go through a smaller aperture opening. Shooting at f22 for maximum depth of field isn't exactly the best idea (I made this mistake for months when I first started photography... oops!).
I wanted to touch on one last aperture value as it's the one I get questioned on the most. The image I shot above was taken at f16, this is the aperture value when you have aperture blades overlapping that creates the star effect when you are taking pictures of lights or the sun. Just wanted to touch on this in case anyone was wondering how to achieve this look (Note: the star look will vary based on the lens you use!).
That's all for this week's lesson. I recommend taking a subject and shooting it at each aperture value your lens offers and looking at the results to help you understand what I tried to explain above. This will help you best understand what is going on as you change your aperture.
Stay true to you.