A quick study of how Aperture effects depth of field

When first started as a photographer, my first question real question is one of the questions I get asked most frequently now... "How do you get those blurry backgrounds?. There's not a single answer. In fact, your focal length, sensor size, subject distance, background distance, and aperture all play huge parts in creating shallow depth of field and the all important bokeh (background blur).  Everyone seems to focus on aperture, and that was honestly the answer I received and subsequently told others. YES APERTURE MATTERS! It makes a huge difference, but what does that really look like, and when do you want to change it? (for the sake of these examples, lets focus on how your aperture effects depth of field, and not about how it effects exposure, that's another lesson for another day)

The first example is from a shoot I did recently for my friend's handmade jewelry shop. The geometric pieces are beautiful, and in this photo I wanted to make sure the shapes on both the bracelet and necklace were both visible.

The image on the left was shot at F/1.4 and the image on the right was shot at F/10 (click image to enlarge)

Most people would agree that the image on the left is more visually appealing. Everything looks softer, and your eyes are drawn right to the lower third where the bracelet is. The background is less distracting and has a great bokeh. The image on the right looks flat, although it's significantly sharper. outside of exposure adjustments to compensate for the different f-stop, the image has the same adjustments applied. Which do you like better? Which would you use if you were featuring the jewelry in a catalog?


The next example is from the same shoot, and actually sort of an accident. I looked at my settings, saw what I assumed was 1.4 on the aperture, but somehow had bumped it up to 14. I knew right away that something was off, fixed it, and decided right then and there that I needed to show people how big of a difference your aperture settings make, which led to me deciding to dedicated a blog to sharing what I've learned over the years and help people take better photos.

I don't need to say much about this. I love shooting wide open, I love how the background disappears, I love how even the shadows are softer on the bricks in the background. Notice in the photo on the left, when zoomed in you can clearly read the letters on the sign and the plants that are so distracting behind her shoulder aren't visible either.


For portraits, shooting wide open (or close to it) is usually my jam. You'll learn quickly, however, that the shallow depth of field can be a disaster for group shots. 

In both of these group photos, I wanted to get as many people in focus as I could, but only had natural light available. In the larger group photo, was able to get away with F/4 because I was shooting with a relatively wide lens (23mm) has a naturally wider depth of field, but if there had been enough light I would have gone even wider to F/8 to make sure the people in back were a little sharper.

I had great light for the second photo, but still didn't want the background to be too distracting. My test image at 1.4 made it clear that I couldn't get everyone in focus, and I couldn't back up any further, so I just went up a few clicks to F/2.2 and while it's not tack sharp on all 5 girls, it's pretty close and was the exact look I was going for.


There's a thousand examples, and this certainly won't be my last post on the topics of Aperture and Depth of Field. Coming up soon: How Aperture can effect dynamic range?!?!?!