Aperture – the “Blurry Background” Tutorial | Ethereal Exposures Photography

One of the key features in professional pictures is that beautiful blurry background behind the subject. Even before I knew anything about anything in photography, I loved this “style”. In fact, when I consulted with our wedding photographer, I specifically requested “images with blurry backgrounds”. Ha ha ha!!! Just goes to show when executed well, a simple technique can be impressive. And, although there are some tricks to getting a blurry background none are very hard to execute … So today, I will reveal the secrets here in the article, Aperture – the Blurry Background Tutorial. So let’s get started …

To get proper exposure for an image there are three primary settings to consider that makeup the exposure triangle: Shutter Speed, Aperture, and ISO. We talked already about Shutter Speed and how that setting on your camera controls how motion is captured. If you missed the article, click on the term Shutter Speed to access. Aperture is the second setting in the exposure triangle and influences depth of field or the amount of the picture that is noticeably sharp in front of and behind the part of the picture where you are placing your focus point.

The hardware inside the camera that actually controls the aperture opening is called the iris and it functions similarly to the pupil in your eye. Do you remember back in biology class in high school where they talked about the pupil and how it gets bigger or smaller to let more or less light in? Yup! That is how the iris functions to control the size of the Aperture in a nutshell. Aperture is related to the size of the opening whereas an f-stop measures the amount light that travels through that opening and is received by the camera’s sensor. When considering how your camera calculates F-stop aperture is taken into account, but is not the only factor to be taken into consideration. The other important measurement that is included as part of the formula is the focal length of the lens. So effectively the formula for calculating the amount of light entering the camera, as represented by the F-stop measurement, is the focal length of the lens in millimeters divided by the diameter of the Aperture in millimeters. This is important because as the focal length gets longer a larger Aperture opening is needed to maintain the same F-stop number. Each full stop either halves or doubles the light. When adjusting the F-stop value normally it is done in either half or third stops based on how you have your camera setup.

Really the important thing to know is if your F-stop is a low number then you are letting in more light and a less of your picture will be noticeably sharp beyond your focus point. If your f-stop is a high number you are letting in less light and more of your overall photo will be noticeably sharp.

The below image of my daughter, Aurora, showcases this technique. This picture was taken at an F-stop of 3.5 with a 24 – 70 mm lens. As you can see, the background, which is a friend’s living room, is pretty blurry. By blurring the background, your eye is drawn to your subject without the surrounding distractions.

Since adjusting Aperture also adjusts how much light is let into the camera, you will want to balance your exposure by adjusting ISO and Shutter Speed to get your desired effect. If you would like to play with your Aperture and not worry so much about the other two settings, move your dial to “A” on Nikon or “Av” on Canon. This stands for Aperture Priority and as long as your ISO is set to auto, the camera will adjust both ISO and Shutter Speed for you so you can focus on just playing with the Aperture setting in a somewhat controlled setting.

One of the activities, Adam and I did when we were learning about Aperture was to diagonally line up a few figurines from our nativity set (it was Christmas time). Focus on the first one then raise the Aperture slowly while snapping a picture at each stop to see how and when an additional figure became sharp. For the sake of this article, we redid this exercise with the candles I have on my kitchen table.

If you give this exercise a try, I’d love to see your pictures and hear your thoughts. Please comment below.

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