The big question for new photographers is, “How do I get the pretty blur in the backgrounds of my photos?” I can remember wanting to know the same thing when I started out. It actually wasn’t very tough to do. All I used to do was zoom in as much as I could with my kit lens and somehow the blur would just magically show up. Which is weird, because the more I zoomed in, the smaller the aperture would get inside of the lens. Typically, the smaller the aperture, the deeper the depth of field, not the other way around. Ah! But proximity to the subject plays a role as well. The closer you are to your subject, the more shallow the depth of field. But I’m getting ahead of myself here.
Okay, there are two things that control the pretty blur (bokeh) you see in the backgrounds of so many pictures on the internet. The first is aperture size inside of your lens and the second is how close you are to whatever it is you’re taking a picture of. Let’s get the distance thing out of the way first. If you set your camera to f/5.6 aperture while in aperture priority mode and stand two feet away from something (all the way zoomed out or with a prime lens) and take a photo of it, you’ll definitely see some blur in your background. If you keep the same aperture size and stand 15 feet away from that same thing and take a photo of it, you’ll see a heck of a lot less blur. So basically, the rule is that the closer you hold your camera to something and take a picture of it, the more blur will appear in the background of your photos. That’s just the way it works, which can sometimes be confusing because of what I’m about to tell you next.
When people talk about isolating their subjects, they’re primarily talking about blurring out anything that’s not important in the image. Let’s face it, if everything in a portrait was absolutely sharp, the person would get so lost in it, no one would know what you wanted to take a photo of. By blurring out all of the non-essential objects in a scene, you’re prioritizing, or highlighting, the most important thing – the person. The best way to control how much blur is in an image is to set your camera to aperture priority mode (A or Av on the top dial) and then adjust the aperture size by rolling the dial that’s on the top of your camera or on the back of your camera back and forth. If you’re using a tripod, you can play around and take the same exact photos over and over again while changing the aperture size. You’ll immediately see the effect of each f-stop on the appearance of your photos. If you take a picture of a scene with your aperture set to f/22, almost everything in the image will be sharp (depending on how close you are to things) and if you set your camera to 2.8, you’ll see lots and lots of blur. Generally speaking. If you’re taking landscape shots and everything is ten miles away, you most likely won’t see much of a difference.
I just want to let you know that I have my camera set to aperture priority mode 90% of the time I’m out there photographing. Sometimes that’s because I want the bokeh I just wrote about, but other times it’s because I’m trying to control the light that comes into my camera. I also like to dictate the shutter speed by adjusting the lens’s aperture size, but that’s a topic for another day.
So there you have it. Both distance and your aperture setting will control how much blur you’ll get in your images. What is required is lots of experimentation to see what the effects of different circumstances will be. Don’t worry, it’s a lot of fun.