Four ways to achieve shallow depth of field without buying the iPhone 18 Pro

iPhone 18 Pro's Variable Aperture Lens: A Closer Look at Depth of Field and Photography Capabilities

The variable aperture lens of the shiny new iPhone 18 Pro goes almost one stop wider than the fixed aperture lens in its predecessor: up from f/1.78 in the iPhone 17 Pro to f/1.48 (a smaller number is wider). This improvement in maximum aperture allows more light to reach the sensor, which can enhance low-light performance and provide a slight edge in background blur capabilities. While the change is modest in numerical terms, it represents a meaningful step forward in optical design for Apple's flagship smartphone camera system.

Background

In principle, this will allow for slightly shallower depth of field, enabling greater separation between your subject and the background – although it’s a relatively small difference. The jump from f/1.78 to f/1.48 equates to roughly a 0.3-stop increase in light gathering ability, which translates to a subtle but measurable improvement in bokeh quality under ideal conditions. However, Apple emphasizes that this hardware change alone is not the primary driver for achieving strong background separation in iPhone photography.

The most obvious method is, of course, to use Portrait mode, which is specifically designed to allow people to be very clearly separated from the background. This is a completely artificial effect using computational photography (assisted by LiDAR, on models that support it) to identify the subject and to apply an artificial blur to everything else. Early versions were extremely crude, but it’s become remarkably good in the last few years, with improved edge detection and more natural-looking blur transitions that rival dedicated cameras in many scenarios.

Specifications

The variable aperture lens in the iPhone 18 Pro opens up to f/1.48, compared to the fixed f/1.78 aperture on the iPhone 17 Pro. This represents an increase in maximum aperture size of approximately 25% in terms of light-gathering area. While not a full stop, this change places the iPhone 18 Pro among the wider-aperture smartphones currently available, though still behind some Android competitors that offer f/1.4 or wider fixed apertures.

All else being equal, the longer the focal length, the shallower the depth of field, and so using the telephoto lens on an iPhone can allow us to achieve a somewhat blurred background. The iPhone 18 Pro continues Apple’s trend of incorporating longer focal lengths in its telephoto module, building on improvements seen in the iPhone 15 Pro and later models. This optical advantage, combined with subject distance and positioning, plays a more significant role in background blur than aperture alone.

Features

The second approach is Macro mode, which will be automatically enabled when you get extremely close to something. With this engaged, the iPhone selects the wide-angle camera, which can focus at extremely close distances. In this mode, only a few centimetres will be in focus, with everything beyond it increasingly blurred. As you might notice from the example below, you should be prepared to spend a lot of time dusting and cleaning before attempting to photograph anything using this mode! You’ll know the mode is active when you see the yellow flower symbol in the bottom right of the display.

You can also achieve a similar result with the standard camera by getting very close to the subject. For example: Just tap on the object or person you want to be in focus before taking the photo. This technique leverages the inherent optical properties of close focusing, where depth of field naturally decreases as subject distance diminishes, allowing for creative blur effects even without specialized modes.

Combining three methods works best: Select the telephoto lens, get your subject as far away from the background as possible, and get as close as possible to your subject. This is the best approach to take when photographing people, and is especially effective with the iPhone 15 Pro and later due to the longer focal lengths. This triad of techniques—optical choice, subject-background separation, and proximity—maximizes the potential for background blur regardless of aperture limitations.

Performance

The wider and variable aperture lens is only one of the new camera features of the iPhone 18 Pro, so you may still want to upgrade if photography is a key application of your phone. However, if background blur is your goal, there are other ways to achieve the same thing that may not require the latest hardware. Computational methods like Portrait mode have matured significantly and can produce convincing results across a wide range of lighting conditions and subject types.

Real-world testing shows that while the f/1.48 aperture does provide a slight advantage in low-light scenarios and marginal improvements in background separation, the difference is often imperceptible to the casual observer. The computational photography pipeline in recent iPhone models has become so advanced that it can simulate shallow depth of field with impressive accuracy, reducing the reliance on wide apertures for bokeh effects.

Price and Availability

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These promotional offers are presented alongside the technical discussion, reflecting common retail associations with Apple product launches. While not directly related to the camera capabilities of the iPhone 18 Pro, they represent potential ancillary purchases for users investing in the Apple ecosystem.

Verdict

The iPhone 18 Pro’s variable aperture lens, opening to f/1.48 from the iPhone 17 Pro’s f/1.78, offers a modest but meaningful improvement in low-light performance and theoretical depth of field control. However, for achieving strong background blur, users have multiple effective alternatives—Portrait mode, Macro mode, close-focus techniques, and telephoto lens utilization—that often deliver superior or comparable results without requiring the latest hardware. Ultimately, the iPhone 18 Pro represents an evolution rather than a revolution in mobile photography, where computational intelligence continues to play as vital a role as optical specifications.