During photo walks, workshops and in our online comments we have been asked many times how to create bokeh and achieve a shallow depth of field, in effect removing distracting elements from the background and turning an otherwise boring set into something dreamy and magical. In answer to those who asked, we wrote this five step guide to help you understand and master the art of bokeh, at the same time unlocking the full potential of your camera equipment.
Not only is Bokeh beautiful, but it also happens to be a key story telling element. Once understood, it will open your eyes to new opportunities and improve your work by adding additional punch, wowing your audience.
Our band name ‘Bokeh Monster’ came from the frequent use of the technique; shallow depth of field is one of the many ingredients to our unique style. By removing the distracting elements from a background through the use of shallow depth of field techniques, everyone we photograph can be compared on a even playing field. Context and placement are subtracted from the distraction equation, isolating and honing in on a subject's beauty for honest appreciation.
First of all, lets define bokeh. Bokeh is the Japanese term for the out of focus elements in an image, the optical effect which transforms a crispy background into a smooth, sometimes abstract and/ or gooey magic.
The degree of bokeh which can be achieved depends on a number of factors,
- Focal length
- Focal distance
- Background separation
- Sensor size
Don't worry if the technical jargon does not mean much right away, our guide covers each element to help you on your way to mastering the art.
Focal length is an optical measurement relating to the field of view in a image. Measured in millimetres (mm), it typically ranges from 8mm (ultra wide angle) through to 200mm (telephoto). It is possible to buy super telephoto lenses which have focal lengths up to 1200mm, but with long focal lengths the size, weight and cost also exponentially increase.
The longer the focal length becomes, the shallower the depth of field and the more dramatic the bokeh is as a result. For example, look at the image below. It was made with an 85mm lens (typical portrait focal length) looking across a two lane street, using the adjacent buildings and their shop lights as the background. Due to its mid-range focal length it has the ability to easily create beautiful bokeh, and the background distractions quickly melt away.
On the flip-side, if you use a wide angle lens, known for their ability to retain a lot of the scene in focus, it becomes much more difficult to achieve any bokeh effects. For this reason, landscape photographers favour wider focal lengths, the image remains crystal clear across the entire frame and every detail can be examined at great length. For example, the image below was made at 24mm. It is significantly wider than the previous image at 85mm, and as a result the entire scene is in focus (do not confuse the water motion with being out of focus).
Focal length is also a key story telling element, depending on your choice, not only does the field of view alter but also the depth of field capabilities. Therefore, in order to reduce the depth of field and maximise bokeh, selecting longer focal lengths are key. The tipping point between a wide lens and the start of the telephoto focal range lies between 35mm-85mm.
In every lens there is an iris, the iris dilation refers to the aperture. It is either automatically controlled by your camera or you can take charge over the artistic option it provides. By manipulating the aperture you affect two important photographic elements,
- Light transmission to the sensor
- Depth of field
By closing the iris, the light entering the camera is reduced, darkening the overall image, and at the same time increasing the depth of field (reducing bokeh effects). So in order to maintain or achieve the shallowest depth of field, and maximise bokeh, keep the aperture as large as physically allowed by the lens. The maximum ‘F stop' (aperture) your lens allows is written close to the front lens element; lenses which allow larger apertures get increasingly more expensive.
Normally cheaper lenses found in point and shoot cameras, super zooms and DSLR kit zoom lenses suffer from small apertures. Hence their ability to create bokeh is limited. The larger the aperture becomes, the larger the iris opening has to be, hence the more glass is required to produce the lens, increasing cost and manufacturing complexity. Sadly there is no cheap route to bokeh, pursuing this effect does force you to dig a little deeper and buy the slightly more expensive.
Prime lenses have no zoom and are designed for maximum optical quality at a given focal length. This style of lens typically has a much larger aperture (iris can open wider, more light enters the lens and more bokeh is produced). Although their counter-part zoom lenses usually replace whole sets of primes, they are the cheaper option and during their design for versatility have to compromise on aperture, hence achieving less dramatic bokeh.
For our work we rely on a full set of prime lenses ranging from wide angle focal lengths through to telephoto masterpieces (14mm F2.8, 23mm F1.3, 35mm F1.4, 56mm F1.2, 90mm F2.8). The prime choice does require us to carry more equipment; however, with each lens excelling at beautifully smooth bokeh, the choice is easy.
The best example and effect of focal distance (the distance between the camera and the subject) comes from macro photography, where the focal distance is small. Macro distances can be as short as 15cm, however specific lenses are required to be able to focus this close and because the distance between the camera and the subject matter is so small, there are several challenges which have to be overcome. Including razor thin depth of field, the depth of field becomes so small it is really tough to keep enough in focus to make the image recognisable. For example, the image below of the red mushroom amongst the green forrest moss floor; while the mushroom is in focus, the surrounding green moss falls away in a matter of mm behind and in front of the mushroom.
Although macro photography is an extreme example of the effect, it does illustrate the bokeh relation due to proximity incredibly well. The concept can be easily translated to other areas of photography too. Getting closer reduces the depth of field, and can be capitalised on as long as the composition is not compromised.
Also note, prime lenses usually allow you to get much closer than a zoom. Again, the argument of a single purpose optic when compared with versatility. Compromises have to be made somewhere.
Just like the camera to subject distance plays its role, so does the distance between the subject and the background. If you wish to include the background (providing context and placement), move the subject close to the focus plane. Alternatively, if there are background distractions or it is messy, it might pay to clean up the exposure a little by melting it away. Separating the subject from the background achieves this; the further away the subject is from the background, the more blurred the background becomes, isolating the subject. For example, in the below image, the further down the street you look, the more blurred the elements become as the distance between the subject and the background increases.
Camera sensor size is a fixed parameter, something which cannot be altered unless purchasing a different camera body. Below are the typical sensor sizes, increasing in cost along side their bokeh ability.
- Micro 4/3 - 18mm x 13.5mm
- APSC (1.5x Crop) - 22.7mm x 15.1mm
- 35mm (Full frame) - 36mm x 24mm
- Medium Format - 50.7mm x 39mm
Larger sensors with the same focal length and aperture have an inherently smaller depth of field. Unfortunately the larger the sensor becomes, so does the complexity of manufacture and the cost goes up exponentially.
For most photographic work (unless you are printing billboards) a medium format camera is unnecessary. 35mm and APSC are the most common sensor sizes and currently have a great price to performance ratio. This is why they are used in the main stream DSLR and mirrorless camera brands.
Modern advances in technology have even seen APSC sensor performances match their bigger brother, the 35mm sensor. So it becomes a trade off between a little extra bokeh vs the cost of a full frame camera. Just something to keep in mind when making the next camera purchase.
Lets recap, in order to maximise bokeh and get the most out of your equipment, follow the five tips below:
- LONG FOCAL LENGTH – longer lenses, greater than 35mm make it easier to create bokeh.
- LARGE APERTURE – the larger the aperture (lens ‘F Stop ’ number) the more bokeh is produced.
- SHORT FOCAL DISTANCE – get closer, like the famous quote by Robert Capa “if your pictures aren’t good enough, you're not close enough”.
- LARGE BACKGROUND SEPARATION – If possible take a few steps back and take your subject with you, the more separation you can achieve, the quicker the details will melt away.
- LARGER SENSOR – Bigger is better, but are the $$$ worth the additional bokeh? Only you can decide.
At this stage all five concepts should make sense, if not, please re-read the relative sections or leave a comment below.
Bokeh is an art, remember, so even if you know what factors influence the creation, there is no replacement for content and story. Practice and chose your background carefully, not everything blurs equally and different lens designs have their own unique blur characteristics.