So you bought your first lens besides the one that came with your camera or maybe it’s not your first lens purchase. Either way, I’m betting you have a 50mm f/1.8 or a 30mm or 35mm with a similar aperture. It’s very common to buy a lens like these because they have a wide aperture, or low f-stop. Shooting at f/1.8, or even f/1.4 means lots of blurry backgrounds and the ability to shoot in the dark. That blurred background is often referred to as bokeh. If bokeh isn’t a new term for you, then go ahead and shout it with me - BOKEH!

Let me bring my audience back a few steps before I go on. In photography (and video too), the aperture, shutter speed, and ISO (gain for video) determine your exposure. The aperture is measured as a ratio of focal length to the diameter of the lens’ opening. If you’re OK with math, you’ll know that ratios are a little counter-intuitive - the lower the number, the bigger it is. For example 1:1 would mean the focal length is equal to the diameter of the aperture (lens opening). If you had 1:3.5, then the aperture is smaller than the focal length. In photography, we just change how this appears. We simply assume the 1 and colon are present and call it an f-stop measured with f slash. So, a ratio of 1:3.5 would simply be f/3.5 - though most lenses still show 1:3.5 and so on when you examine the print around the lens. Following the same idea that a smaller ratio means bigger, f/1.8 would indicate the aperture is wider than f/3.5.

Now, notice I never mentioned anything that indicates a measurement of light gathering relating to the f-stop, or how wide the aperture is. The amount of light gathered is not measured in the f-stop calculation. Generally speaking, though, it can give a pretty good indication of how much light will be gathered. If the aperture is opening wider, then more light can pass through, right? Yes, this is true, but it doesn’t mean all lenses at f/1.8 will gather the same light. Remember, this is just a ratio, not a firm measurement. There will be slight differences in actual light gathered from lens to lens. If you want a measurement of light gathered, look for t-stops as a measurement (t/1.8, t/3.5, t/5.6, etc.). Most lenses don’t have their t-stops measured, however.

What is Bokeh?

Bokeh is a popular word in photography and many photographers feel it’s necessary to have in their photos in order for their work to appear professional. But what is it? Bokeh is the way the blurred parts of a photo appear due to shallow depth of field. With a wide aperture such as f/1.4 on a lens, very little in the photo can be in focus - this is shallow depth of field. The parts not in focus is the bokeh. Bokeh can appear swirly, which is a unique look from certain vintage lenses. Bokeh can appear soft and smooth. Bokeh can also appear sharp and rough. Lights can also appear as different kinds of shapes in the bokeh - we call these “bokeh balls.” Bokeh balls can be round, not quite perfectly round, or doughnut shaped.

Why do so many photographers care about bokeh?

Bokeh is a term thrown around so often in photography, reviews, how-to content, etc. that it gives an impression that it’s important. It is, to an extent. However, it’s often used as a crutch rather than something that takes skill. It’s common, especially with new or beginner photographers, for them to get a lens with a wide aperture, lock the lens at the widest aperture, and shoot almost exclusively wide open. The reasoning behind it is usually “bokeh.” But why?

Most of us today are used to taking photos on our phones. Maybe some of us have a point and shoot as well. These cameras physically just can’t produce a shallow depth of field, or bokeh. Instead, smartphone manufacturers had to come up with clever ways to simulate shallow depth of field with software. Because it’s so easy to achieve a shallow depth of field with a DSLR or mirrorless camera, doing so gives the impression of using a professional camera, regardless of experience or skill. And if you shoot wide open regularly, I am sorry if I have offended you.

Using shallow depth of field creatively

Don’t shoot wide open to give the impression you have a professional camera. Use the depth of field with intention. Adjust your aperture to fit the purpose of the shot. You should not lose contextual details of the shot or scene because of a need for bokeh.

Let me give an example. I was browsing a photography forum and an amateur photographer posted a picture of a dog in a dog bed for critique. I might have been a little too tough on my feedback, but it kind of inspired me to write about this topic too. The photo only had the dog’s head in focus and the rest of the photo fell off into a blur very quickly elsewhere in the photo. Reading some of the discussion, I learned the photo was shot at f/1.4. The lighting showed that shooting at f/1.4 wasn’t necessary and it’s difficult to keep things in focus with an aperture open that wide also. The details and context of everything else in the photo was lost to the shallow depth of field and the dog’s head felt out of place and stuck out like a sore thumb over the blur. The “bokeh” in this shot was far too distracting too.

You should use shallow depth of field to isolate your subject from the rest of the shot. The dog photo did isolate the dog’s head from the rest of the scene, but the head felt like it was missing a body. If the photographer had stopped down the lens, the dog’s body would have remained part of the focus and the dog bed and other elements of the scene would have stayed relevant.

When shooting your own photos, keep in mind the other elements in the scene. Keeping some context of the rest of the scene will help your photos remain meaningful to your audience. You should think very intentionally about what details are still visible and not in your shot. It will help tell a story or setup an emotion with the shot. Context is crucial.

When it’s OK to blur the background

I’m not arguing that you shouldn’t take advantage of the wide aperture of your new or favorite lens. There are times when using a very shallow depth of field is OK.In fact, there are situations when you just can’t avoid a shallow depth of field. For instance, aperture isn’t the only thing that creates a shallow depth of field - telephoto focal lengths can too. That means zooming into your subject will ultimately produce shallower depths of field, regardless of your aperture. Also, using extension tubes can significantly shrink your depth of field.

If you know me personally or have followed me for some time, you’d know I love shooting live music. Live shows usually mean dark venues. When shooting concerts, especially in small venues, you need to capture as much light as possible. This will mean opening your aperture. If necessary, shooting wide open will work well to your advantage. The shallow depth of field can be forgivable in this situation too because you’ll usually capture shots of one musician at a time. Anything in the background can still be identified as being a musician or part of the stage. The colored stage lights will also add to the shot. More importantly, a lot of the background contains elements we don’t want to see and can make our shots uglier. For example, shooting towards the side of the stage might reveal packed equipment from upcoming bands, duct work, or other elements of the building that don’t make up the stage presence. Blurring these elements means it’s less distracting to your shot. In fact, many concert photos include very dark or black backgrounds to hide these distracting elements - only the darkened backgrounds are usually done during the editing stage and not in camera. The problem with shooting at such wide apertures for a concert is is the difficulty in getting focus just right. Ideally, you want to focus on your subjects’ eyes. Except, live performances can be fast paced and your depth of field can be so narrow that shifting your body weight can be enough to throw focus off. For this very reason, I usually stick to apertures around f/2 on my APS-C camera.

You may want to get creative with shallow depth of field too. A common technique is to use string lights like you’d hang around your home for holiday decorations. Putting them behind your subject, using a shallow depth of field, will produce an array of bokeh balls, or round lights, that can add texture and pattern to the background. Another technique is to string the lights from your subject to the camera lens. This will produce a sense of depth and varying sizes and shapes of the bokeh balls.

When shooting macro photography, depth of field can both be your friend and enemy. Ideally, you want as much to be in focus as possible. This means stopping down your lens and adding light. However, you may find yourself shooting at an angle where the background could be distracting. When possible, you’d put something in the way light a piece of paper to serve as the background. However, when that’s not possible, using a shallow depth of field can be helpful to hide a distracting background. In fact, when your depth of field is shallow enough, the background can lose all detail and become a colored background instead. Just keep in mind that you risk losing parts of your subject to the shallow depth of field as well.

If you want to blur the background without resorting to a very wide aperture, increase the distance between your subject and the background. For instance, stage your shot so the background is further away from your subject. Depth of field, or the area that’s in focus, is limited by a distance away from the image sensor. That means that at a certain aperture and focal length (the two main factors in determining depth of field), focus will exist between x and y feet or meters. Anything in front of x or behind y will be blurred. So if you want to blur the background without blurring your subject, keep your subject between x and y, push your background far beyond y.

With made up numbers, this translates to focus being between 6 and 9 feet from the image sensor when shooting at 50mm with f/2.8. Everything 0-6 feet from the lens will be blurred and everything 9 feet and beyond will be blurred as well. Again, these are made up numbers to illustrate this example.

There are apps to calculate these numbers, just look up depth of field calculator. You punch in your focal length and aperture, the app does the calculation. There’s also the concept of hyper focal distance, however, and there are apps for this calculation too. Hyper focal distance cheats depth of field limitations. At the hyper focal distance, everything from a certain distance and beyond to infinity will be in focus, meaning no blurry background at all. Just be aware of this.