Depth of field is one of the tools most used by photographers to give three-dimensionality to the image and highlight subjects in an environment. So we look for bigger sensors, brighter optics, and ways to highlight and get those bokeh-sensational blurs. Hence, for many, mobile phones do not meet that need. What can we do about it?
Understanding the limits
Aperture, focal length, and focal plane distance versus subject: these are the three tools we need to master in order to achieve the depth of field we want. In mobile photography there are two variables that we cannot change, the aperture and the focal length..
On the one hand, most mobiles have very wide apertures, which in theory would help us to obtain a much shallower depth of field. However, the lenses are wide angles, which increases the depth of field by the way the light converges on the sensor.
This leaves us only with the distance between sensor and subject to try to achieve a greater or lesser depth of field. As with other clipped sensor formats, the angle of view of our systems is different and we need to compensate for it by getting closer to or further away from the subject. When we can get closer, we can reduce that depth of field. However, that is not an option in some photographic fields like portrait due to perspective distortion, so we stay at a distance for a more natural perspective.
Due to this, it is difficult to obtain that shallow depth of field that separates subject and background in our images.
Exceeding the limits
Mobile photography then gives us two physical options to achieve the depth of field effect.
The first is to get closer to our subject. The closer we can focus on the subject, the less the background will be in focus. This will be useful mainly for some small subjects and detail shots.
The second is to apply the depth in reverse. If we need to give three-dimensionality or depth to the image and our subject must be far away, we can take advantage of it to bring elements closer to the objective such as papers, plastics or other objects that are out of focus being so close to the target. This will help us give our image more depth.
On the other hand, if we want to reduce the depth of field, we also have two ways of doing it through the use of software.
The first is the device’s own bokeh effect. With advances in computational photography, higher-end models are already able to produce a more natural depth-of-field effect than before. While artifacts and bugs from that fake bokeh are still felt on some models, most present interesting results.
Create our own edition to perform the fake bokeh. The most effective digital way to obtain the blur we want at a digital level is by using the tools offered by editing software. A good selection and create the blurs ourselves. It is a longer process, but you can get better results.
As technology continues to evolve, we will be able to achieve better results that are closer to that most characteristic style of traditional photography. What tricks do you use to get a better depth of field in your mobile photos?