Have you wished your photos to have that soft creamy background, that you see in magazines? Gives that three-dimensional look to an image. The buttery smooth background makes your subject pop out of that frame. Another widespread term used for background blur is ‘Bokeh’. It’s a Japanese reference for ‘blur’.
There are ways to achieve this effect in post-processing, but I will discuss how to blur the background of photos in camera, while you shoot.
Four main factors that affect the amount of blur we can create
1. Shoot at a wider aperture.
There are numbers (1:3.5-5.6 in case of a typical kit lens) on the body, and around the front element of any lens, referred to as maximum aperture values. Most zoom lenses have variable maximum aperture across the zoom range.
1:3.5-5.6 indicates that the maximum aperture at lowest focal length is 3.5 and the maximum aperture at the longest focal length is 5.6, for that given lens.
Smaller the number, wider the aperture. The numbers and aperture width are inversely related, counter-intuitive, I know. If the aperture opening is small ( i.e. numeric value high – f/16 or f/22), most of the frame is in focus. As we start increasing the aperture size (or decreasing the aperture number), the slice of the scene (near to far) that is in focus will begin to reduce. Wider the aperture, shallower the depth of field.
To begin with, move out of that auto shooting mode. Auto mode will choose its aperture automatically, smart. The easiest way to take control of the aperture is by switching to Aperture priority mode in your camera. Rotate the aperture dial to its smallest numeric value. That will give the widest aperture of your lens at that particular focal length.
The wider aperture allows more light to enter your camera. So your shutter speed/ISO will change to counter that effect.
Image Source – Snapaholic.com
2. Place your subject far from the background
The second step, place your subject as far as you can from their background. If space is tight, move a bit and recompose. But see that there is enough distance between the subject, and whatever is behind them. Increase the distance between subject and background. This adds up to the amount of background blur.
As shown in the above illustration, the image goes out of focus, on both sides of the depth of field range. Make use of this lens property.
3. Get closer to your subject
Third, move as close as you can get to your subject. Without compromising the composition much, that you are looking for. This adds up to the previous effects achieved and creates an even more blown out background. The closer you focus, better are the chances of your background to go out of focus. That is why it is difficult to keep macro (close up) shots all in focus. Get close to your subject.
4. Longer focal length
Higher focal lengths cause image compression. This is the nature of lens optics. So longer focal lengths naturally tend to give a smooth background. For the final step, zoom all the way in, and get that visually appealing photograph.
Lower focal lengths provide great detail across a scene. Everything in frame gets into focus. That is why photographers use 50 mm and beyond for portraits, to get that separation. Longer focal lengths give shallow depth of field.
Put together all the steps discussed, and you will be able to pull out the best possible bokeh with your camera.
Camera sensor has its role
Sensor size is another factor that affects the quality of blur or bokeh. For a given focal length and aperture, a 35 mm format (full frame) camera will give better out of focus softness than a smaller sensor camera (e.g. APS-C or micro 4/3).
That is why it is difficult to get a blown out background when you are shooting with your phone or a compact pocket camera. They have smaller sensor compared to DSLR. On top of that, most cell phones use fixed focal length lens of around 28 mm. Both these factors add up to give an everything-in-focus image.
You can still manage to squeeze out some decent blur out of your phone or compact camera. Switch to macro or close-up mode and move closer to your subject. If your point and shoot can zoom, go all the way in. Try to avoid any lower focal lengths if you want the bokehlicious background.
Quality of blur
Bokeh is often categorized as good or bad. A good bokeh will have creamy background with smooth round circles of light. Bad bokeh is anything that distracts the viewer. It may seem irregular with sharp edges around the out-of-focus light sources.
Lenses that help
It is easy to achieve a soft background with lenses that have a wider maximum aperture of f2.8, f1.8, or even wider. Zoom lenses are available with constant wide apertures of f2.8 or f4. But they are relatively heavy, and pricey.
A reasonable way to creamy bokeh is to get a prime lens (single focal length). Prime lenses generally come with a wider maximum aperture value, than kit lenses. 50mm f1.8 is an excellent great value prime lens. It’s cheap across most brands, and fantastic in image quality. It is a decent focal length for portraits, and bokeh quality is superb.
Roll up your sleeves
Grab your camera, put to test all the above-mentioned techniques. Pick a long focal length, turn that aperture dial to its lowest number (maximum aperture).
Taking 18-55 mm kit lens as an example, zoom all the way up to 55 mm, and dial the aperture value to 5.6. Place your subject closer to you than the background. Results will amaze you.
Soft background isolates and enhances the subject, and gives that professional look we all crave for.
Check out this illuminating video by Tom Greenwood from sydneyportraits.com.au
How were your test shots? Do you have other tips to achieve super fine bokeh? Was the content helpful? Please share your thoughts, questions, and comments below.