I've saved my favorite for last. Aperture controls your depth of field, or how blurred or crisp your background is. Since I am very into Macro photography, aperture is my best friend. This is what creates that yummy blurred background. It also is responsible for the beautiful bokeh that you see here.
The circles of light are referred to as "Bokeh"
ISO 100 ~ 60mm ~ f/2.8 ~ 1/10 sec
© Corrie M Avila
The circles or orbs of light you see are actually out of focus christmas lights. By having a focal point (the teacup) in front of the lights, and by using a f/stop of 2.8 (large aperture, small f/stop #) I was able to create this look for my photograph.
Detailed View of New York City
ISO 100 ~ 50mm ~ f/16 ~ 1/200 sec
© Corrie M Avila
Basically your f-stop number is your aperture. When you have a wide open aperture it is a small number. When you have a small aperture it is a bigger number. This is tricky in concept because it goes against logic.
The aperture controls how much light is let in. Lets think of your eye again. If you step into a dark room, your pupil opens really wide and lets in a lot of light (small f/stop #). When you step outside on a very bright day, your pupil is very small and lets in very little light (larger f/stop #). While your shutter speed is how fast your shutter opens and closes, your aperture is how wide or small the opening to the shutter is (just like the pupil of your eye).
Okay, so how do we use this information? Before you go to take a photograph, think about what your priority is. If it is freezing or blurring movement, adjust your shutter speed first. If it is controlling your depth of field (i.e. having a crisp or blurred background) adjust your aperture first.
In the following diagram I visually explain the difference between a wide open aperture (small f/stop # = blurred background) and a small aperture (large f/stop # = crisp background).
As you can see from this diagram your aperture or f/stop number can completely change the look of your photograph. When you fully understand and embrace this component of photography, you will begin to see the multitude of creative opportunities available.
The range of f/stop numbers depends on your lens. For the above example, I used my macro lens which happens to have a larger aperture (f/2.8) than my telephoto lens (f/3.5). Regardless of the range of your lens, you always have the ability to change your aperture and in turn can determine your depth of field (blur vs crisp background).
Homework for Tutorial 5:
1) Locate where your aperture is on your camera. Get comfortable with this setting so that you are able to adjust your aperture with ease.
2) Put your camera in AV mode (This is Aperture Priority). Again, do not get comfortable here. This is just for now to allow your camera to figure our the other settings while you adjust your aperture. Choose a still life object that won't move or run away from you :) Also make sure that you have a subject and a background. I used the apple as my subject and the tree as my background in the example above. Put your aperture to the lowest number you can. (Remember lower number means larger aperture = blurred background). Make sure your focus is on your subject and then take the photo. Write down the settings of your camera. Next change your aperture to the highest number it will go. (Remember higher number means smaller aperture = crisp background). Make sure you are focusing on your subject again and take the photo. Write down your settings once more.
3) Now compare your photos. Can you see a distinct difference in your background? Did you ISO change at all? If it did change, do you know why?
Now that we have completed the 3 components of Exposure, we will next work on the light meter and combining all you have learned together. You are closer than you think to photographing in Manual Mode. If there is an area you still need help with, please feel free to reread the tutorials, email, facebook, or comment below. I am here on this journey with you <3
Continue forward to Light Metering
Capturing the Moment,