“How do you make the background blurry in your photos?” I’ve been asked this 200 million times on Instagram so I figured it would be more efficient to address this question through a blog post rather than replying to individual messages.
Indeed, that background blur, or what the photography community usually refers to as bokeh, is what differentiates the casual iPhone snapshot from a professionally produced image (at least to the layman’s eye), and thus has become one of the most sought after looks in street style photography. Having said that, I feel I need to point out that bokeh does not a great image make. There’s a lot more to photography like composition, creative lighting and color theory than just blurred backgrounds. But we’re not here to debate these things. We’re here to learn how to achieve bokeh in your Instagram images.
1.) The right focal length
You know those numbers on the front your camera lens that read like “50 mm f1:1.8.” They’re not decorative. These figures are as descriptive of the lens as they can be without you having to actually try them out. It gives you an indication of how the lens is supposed to perform and what kind of images it can give you based on its physical characteristics.
The number expressed in millimeters is called the focal length, and determines how wide or tight the field of view is. The longer the focal length (the higher the number), the easier it is get bokeh in your photos. You can expect good bokeh from most lenses above 35mm with apertures of 2.8 and larger.
2.) The right aperture
You know that number that follows the focal length, that one preceded by an f? That’s the aperture. It tells you how much light your lens can transmit on to the sensor when the circular opening is set at the widest. To get noticeable background blur, you need to set your aperture to 2.8 or larger. The lower the number, the larger the opening and the more bokeh you can expect.
But going back to the focal length, if you have a short lens, it’s much harder to get blurred backgrounds even if you have a large aperture. No aperture is big enough to make a super wide lens, like the one installed on your iPhone, have any perceivable kind of bokeh.
Also remember, the faster the lens (meaning the lower the aperture number), the more exponentially expensive it become. Just as an example, a Canon 50mm 1.8 retails for about $100, the 50mm 1.4 for about $300, and the 50mm 1.2 for $1,300. The last is not exactly 10x better than the first in terms of the images it can produce.
3.) The right sensor size
The reason you can’t get bokeh on your iPhone no matter what you do is because its camera sensor is the size of a.. well, at 32 square mm I can’t really find an everyday object that small to compare it to. The typical Canon DSLR, starting from the super cheap EOS 1200D to the EOS 7D Mark II, has a sensor size more than 18x that at 592 square mm. The bigger the sensor, the more bokeh you can get provided that you get your focal length and aperture down. But why does sensor size affect background blur? Move on to the next one to find out why.
4.) The right distance from the camera to the subject
The closer you are to your subject, the more background blur you can get. If you try to experiment, a head shot, where you are considerably closer to the subject than say, a full body shot, will always have more bokeh if they were taken with the same aperture.
The physical reason sensor size from the previous point affects blur is because the larger the sensor, the wider a lens becomes (a 35mm lens on a 1200D behaves differently when mounted on a full-frame sensor 5D – you’ll get a wider scene on the latter), and the closer you have to be to the subject to achieve the same kind of framing.
If you focus far from the camera, no matter how big your aperture is, everything in your shot will be in focus and you will not get any bokeh whatsoever.
5.) The right distance from the subject to the background
Have you ever noticed how style photos are mostly shot in the middle of an empty street? That’s because the farther the subject is from the perceivable background, the most blurry the latter becomes. If you take your photo against a wall, which most bloggers do for some reason that’s beyond my comprehension, you will not achieve any blur no matter what expensive, larger aperture lens you use.