Aperture Basics

The aperture is simply the iris of the lens. By opening and closing the aperture you can control the intensity of the light entering the camera and hitting your sensor. When the aperture is wide open it let's in more light, and as you close it down it let's in less. These adjustments to the aperture are measured in f-stops and generally appear as a sequence. The f-stop sequence is:

f1.4    f2    f2.8    f4    f5.6    f8    f11    f16    f22.

F1.4 is the widest, brightest aperture and f22 is the smallest, darkest aperture in this sequence. With each stop in the sequence you are making the image half or double the brightness. So f2 is half as bright as f1.4, and f2.8 is half as bright as f2. Conversely, f16 is twice as bright as f22, and f11 is twice as bright at f16. In this sequence you can see the effect this has when you only change the aperture.

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By changing the brightness of the image, aperture allows you to adjust when there is too little light or too much light. The aperture also can control the depth of field in an image. Wide apertures have a shallow depth of field and smaller apertures have a much larger depth of field.

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f2.8 Aperture

f16 Aperture

By using wide apertures like the image on the left at f2.8, It allows you to choose which area of the image is the focus. I can make the lemons in focus or I could've made the background in focus and the lemons out of focus. This act of choosing what is in focus is called selective focus. Using small apertures like f16 like the image on the right, I can increase my depth of field. As you can see the background is starting to become clear, and the lemons are completely sharp. This is useful for getting multiple levels in focus in a frame like when people are at different distances but still need to be in focus.

I hope this was able to help you get started with aperture. The best thing you can do is to go out and try different apertures and see how they affect your image.

Aperture terms:

Maximum Aperture: The brightest, widest aperture the lens can be set to. Some lenses are brighter than others (f1.2 /f1.4 /F2.8) while others are darker (f3.5 /f4 /f5.6 etc) This influences price and capability. (Can also reference how dark a lens can go. Some lenses can go down to f32/f64 while others can only be as closed down as f16.)

Wide Open: Shooting at the brightest, widest maximum aperture of the lens.

Stopped Down: Shooting at an f stop darker/more closed than what the lenses maximum widest aperture is.