Bokeh is popular, and the misunderstood element in photography. Due to its proximity to the depth of field, people often misunderstand it and find it confusing to attain a perfect bokeh. Bokeh is a quality of the blur produced in the out of focus subjects in the image. The definition states that the production of bokeh is the process that lens renders the out-of-focus points of light.
The shape of the aperture diaphragm and lens aberrations produces the pleasing effect of the blur in an image. However, a variety of lenses tends to produce good and bad bokeh. The blur observed in the image are the parts that lie outside the depth of field for the delivered focal length of the lens. Photographers use a shallow depth of field to produce images with prominent out-of-focus regions that generate creative pictures.
The most visible parts of an image are around the background highlights such as the light sources and reflections. However, bokeh does not have any particular limitation to highlights but defocuses the parts of the picture that rest outside the depth of field.
Bokeh originates in Japan from the word ‘Boke’ that means haze or blur. The term is also valid for mental haze or senility. The term ‘bokashi’ means intentional blurring or gradation. The term Bokeh popularized in the year 1997 in Photo Techniques Magazine, when Mike Johnston, commissioned three papers on the topic.
Most personalities will agree with the fact that good bokeh is capable of improving the quality of the picture. However, it is unclear about the separation between good and bad bokeh. It is because each lens has a different design and arrangement of the lens group. Due to this, the bokeh achieved is different from one lens to another.
In any case, obtaining the out-of-focus parts in an image is possible. Achieving the blurriness in a picture is possible with the lens. Setting the lens to the widest parameter of the aperture value provides the possibility to create bokeh or the background defocus effect.
According to Nikon, bokeh is this of the autofocus background achievable when shooting the subject using the fast lens and at its widest aperture value. It is, therefore, impossible to define a good bokeh, as different lenses produce different results. Photographers disagree to the presence of good and bad bokeh, as there is no such definition.
The reflection of the shape of bokeh is dependent on the shape of the aperture diaphragm. For instance, circular shaped blades produce softer and rounder out of focus highlights whereas hexagonal shaped diaphragm produce hexagonal results in the highlights.
Photographers also debate that the presence of bokeh is either the main characteristic of reflections and highlights in the photograph or the quality of the entire out of focus region of the image. However, the common factor about bokeh is that is the background defocus or the parts of the image that are out of the depth of field region. The shape and the volume of defocus are dependent on the design, form and size of the lens.
Bokeh and Lens Design
It is difficult to state a good bokeh, but a few lenses are capable of delivering pleasing out of focus areas. The term ‘good’ is suitable for macro lenses and telephoto zoom lenses. It is because they produce shallow depth of field that concentrates on a particular portion of the subject leaving the rest of the objects in out-of-focus.
Bokeh is also essential for portrait photography. The photographer would like to use the shallow depth of field to ensure that the subject stands out sharply against the out of focus background. Determining the characteristic of the bokeh is possible by examining the circle of confusion available in the image. In the blurred background, every point of the light is the reflection of the aperture, which is more or less in the appearance of a disk.
Depending on the correction that the lens receives for spherical aberration, the formation of the circle receives uniform illumination, brighter at the edge, or brighter at the center. Lenses that receive poor correction for the spherical correction show a single shape of out-of-focus disc points at the front and different shaped points at the back.
In certain cases, the various shaped points present in the image prove beneficial because blur circles that have less illumination produce less defined shapes. They tend to blend smoothly with the surrounding, making a pleasing appearance.
According to photographers, there is no such term as good bokeh. However, many agree that an image of the subject in sharp focus and the background blur that is pleasing to view is the good bokeh. Therefore, an image with softer and smooth out-of-focus area looks good and enhances the picture.
Bad bokeh appears due to improper construction of the aperture diaphragm and absence of spherical correction. An image with line, structures, and shapes of different forms in the background is the answer to bad bokeh. Although the background is out-of-focus, it does not completely isolate the subject from the background.
For any lens, the best bokeh capturing ability is at its widest aperture value. For instance, for a telephoto zoom lens of 200mm with a variable f value of 4.5-6 delivers the best background defocus at f/4.5. However, it is important to combine other elements such as focal length, shutter speed, and ISO to achieve soft defocus of the background. A better understanding of the three pillars of photography will prove beneficial in producing good bokeh images.
Achieving good bokeh or pleasing background defocus is also dependent on the lens. Faster lenses provide accurate out-of-focus while slower lenses tend to introduce lines or shades of the background. Although the images are good, they could have been better. The use of the background blur is dependent on individual choice.
Causes of Bokeh
As discussed earlier, the presence of bokeh is due to the construction of the lens elements and the aperture diaphragm. It is the reason lenses from different manufacturers have varying qualities of bokeh. Generally, faster lenses such as f/1.4 or f/1.8 produce pleasing bokeh that a slower variable lens.
The bokeh that is visible in the picture is the result of the construction of the aperture lens elements. Reduced depth of field is achievable by increasing the aperture value (wider at smaller f-stop). The reduction in the depth of field concentrates only on a particular area or the subject while defocusing the rest of the objects or parts in the frame.
The appearance of the bokeh changes from one lens to another because of the multi-leaf diaphragm. The aperture handles controlling the amount of light entering the camera sensor through the lens. Typical designs of the lenses choose eight-blade aperture construction that has either straight or curved blades. Straight blades tend to produce polygon shape while curved blades produce a more rounded opening.
When the opening of the aperture is close to round, the out-of-focus achieved is more pleasing than straight bladed diaphragm construction. Therefore, the cause and the shape of the bokeh are dependent on the design and quality of the lens.
Types of Bokeh
There are two basic types of bokeh – cream cheese and Hollywood. Most photographers refer to them as the best for any given condition.
- Cream cheese bokeh – Photographers refer to cream cheese bokeh as the perfect out-of-focus for an image. Lenses with ‘good’ design and quality produce near-round opening of the aperture that results in cream cheese bokeh. Photographers use the setting for portrait photography, as it defocuses the background while focusing only on the subject. The result is a pleasing picture with the right amount of sharpness, brightness, and background defocus.
- Hollywood bokeh – the second type of the bokeh is the Hollywood bokeh and known for creating distinctive softening of the highlights in a picture. The result is lights or reflections appear soft and round – yet distinctive. There is a possibility to create distinctive shapes with the addition of bokeh kit accessories. They provide the opportunity to produce custom shapes of the lights and the reflections, creating a unique picture.
While the cream cheese bokeh is useful for macro and portrait photography, the Hollywood bokeh is suitable for product photography. Hollywood bokeh also suits portrait photography. However, the background requires the presence of lights and reflections to make it appropriate.
Getting the best out of DSLR
DSLR lenses receive special construction. The quality of the lens material, their arrangement, and the group elements play a crucial role in generating high-quality images. The fast lenses that possess wide aperture openings, such as f/1.4, offer incredible bokeh effect. Telephoto zoom lenses with f/4 are decent but may not be a match to the image captured by a fast lens.
Setting the aperture value to the smallest value is crucial in narrowing the depth of field to create more out-of-focus parts in the image. Nonetheless, the focal length of the lens also matters. A lens with longer focal length decreases the depth of field. For operating a zoom lens, it is preferable to zoom to the maximum focal length and set the aperture to achieve the best bokeh.
Furthermore, it is crucial to focus on the subject and maintain the minimum distance to produce the best bokeh. At the same instance, it is essential to keep the larger distance between the subject and the background. The more considerable distance enables in generating more out-of-focus background.
Bokeh is dependent on the construction, design, and quality of the lens. The fast lens produces cream cheese bokeh while slower lenses tend to produce bokeh that is not perfect. Achieving bokeh is possible with lenses that have wider aperture settings.
Although there is no relative term, that explains ‘good’ bokeh, the effect of defocus in an image is individual choice and preference. Therefore, photographers have complete control over bokeh and produce the right amount of background blur according to the requirement.