Here I’m going to explain a bit more about the caveats of smartphone cameras in the form of a FAQ. I will add that for all their compactness, smartphone cameras produce incredible images, they just have the same limitations all small devices have.

Is the image quality as good as a dedicated digital camera?

Image quality is partially reliant on the size of photosites, the building blocks of digital images. The larger the photosite, the better it is for low-light conditions. Smartphones have relatively small sensors, and therefore are constrained by the size of their photosites. They still produce images with exceptional quality, but there is a reason people choose full-frame and medium sized sensors for professional work.

Regardless of what companies say, image quality on a smartphone will never be as good as those on a camera. The iPhone 14 Pro has a 1/1.28” sensor on the wide camera with a sensor area of 75mm², and a pixel pitch of 1.22μm in 48MP mode (2.44μm in 12MP mode). Don’t get me wrong, the technology is amazing – squeezing a camera with a 7-element, 24mm focal length equivalent lens with optical sensor shift. But those pixels are small, and there is only so far you can scale up a 12MP image. In comparison, a 26MP APS-C camera sensor has photosites that have nearly four times the area of the 14 Pro, which means more light can be captured. It also has twice the number of photosites, more photosites amounts to better resolution.

Are lens elements made of plastic?

Cameras are all about the glass, or in the case of smartphones – plastic. Most smartphone cameras are comprised of lens elements made out of injection molded optical plastic. Now plastic lenses have been around for a long while, and they have benefits and drawbacks. There are many reasons for this, most notably the fact that plastic elements can be molded into much more extreme aspheric shapes, something not possible in optical glass (aspherical lenses are used in high-end optics to create sharper images and reduce or eliminate some types of optical imperfections). Plastic also allows for thinner lenses that have more complex flange geometries.

Are lens apertures limited?

The aperture of a lens controls how much light makes its way through to the sensor, controlling things like depth-of-field (or how much of the scene is in focus). Smartphones that work well in low-light situations, without the use of a flash, have large apertures. The wide lens on the iPhone 14 Pro has an aperture of f/1.78, which allows for good low-light performance, but taken into context, an aperture of f/1.78 has the DOF equivalent of an f/6.1 aperture on a full-frame camera. That makes it hard to produce blurry effects naturally – they are usually added artificially in post-processing. These lenses are stuck with a single fixed aperture, providing limited control of exposure. It may seem like you can change the aperture, but apps that allow the aperture to be changed to increase the amount of background blur are really just adding a certain amount of artificial background blur. Camera lenses can change the aperture, and hence the depth of field, facilitating natural blur, i.e. bokeh.

Do smartphones create natural Bokeh?

Bokeh has to do with unfocused regions in an image, and relies heavily on a shallow depth-of-field. Many smartphones use wide-angle lenses, and as a result, have quite a large depth-of-field (DOF), the distance between the nearest and farthest elements in a scene that are in acceptably sharp focus. The available depth of field increases as the sensor size and lens focal length decrease, which is why smartphone photographs tend to have very large DOFs. Landscapes, everyday shots, even close-ups have very little out-of-focus. How is bokeh created? Through the power of algorithms. The iPhone uses both cameras to create a DOF-effect in Portrait Mode. It combines the photographs taken by the wide-angle and telephoto lenses, and after applying some computational magic, produces a blurred background. There is even a Depth Control feature which allows the bokeh, to be tailored, between an aperture of f/1.4 and f/16. But it is computationally created, and bokeh is a natural phenomena which occurs in part because of lens optics.

Are different lens focal lengths useful?

While these lenses are exceptionally designed for the small space they are required to inhabit, they can not really be compared to the larger glass available in dedicated cameras. Photography is about light, and smartphone lenses are extremely small and so don’t really let in the same amount of light. The 24mm equivalent wide angle lens of the iPhone 14 Pro has an actual focal length of 6.9mm (35mm equivalent), the 13mm is actually only 2.2mm, and the 77mm is only 9mm. Basically the focal lengths often used to described in lenses are in terms of their 35mm equivalents, likely to create better associations. For example a 77mm telephoto lens seems easier to understand than a 9mm telephoto.

To get a bit technical, this means the effective diameter of the entrance pupil (DEP) of the wide-angle 6.9mm lens with a max aperture of f/1.78 is 6.9/1.78 = 3.88mm. Comparing this to the equivalent 24mm full-frame lens, say the Sony FE 24mm f/1.4, and the DEP is 17.14mm, much larger. More area equals more light. Apart from the fixed aperture, and compactness of the lenses, there is another big issue. Smartphone lenses, regardless of how many of them are on a phone, can only cover a finite number of focal lengths. Cameras, especially those with interchangeable lenses, can use optical zoom lenses that cover a very broad range of focal lengths. For example the APS-C lens Fujifilm XF 18-135mm (f/3.5-5.6) covers the full-frame equivalent of 36 to 270mm.