In general, we’re not expecting the iPhone 18 Pro to be a major leap forward from its predecessor. In fact, if you’re currently using an older iPhone, there are solid reasons to consider purchasing the iPhone 17 Pro before next week’s official release.
Among the limited enhancements we anticipate, the most notable one on paper appears to be a variable aperture lens for the primary camera. However, the real-world impact remains uncertain…
Variable aperture enables control over depth of field
One of the most significant differences between photos taken with a DSLR or mirrorless camera and those captured on an iPhone lies in the ability to manipulate depth of field (DOF).
With a traditional camera, using a wide aperture creates a shallow depth of field, typically employed to isolate the subject from the background. Portrait photography is a classic example, which explains why Apple’s simulated shallow depth-of-field feature is referred to as Portrait mode.
Conversely, when photographing scenes such as landscapes or cityscapes, a narrow aperture is usually preferred to keep everything sharp from the foreground to the background.
Therefore, a variable aperture is a standard component of traditional camera lenses. iPhones, by comparison, utilize fixed aperture lenses. (While there are methods to simulate shallow depth of field on an iPhone, I’ll explore these in a separate article following the new phone’s launch, but these remain exceptions rather than the norm.)
A variable aperture lens for the iPhone
We anticipate this to be the year when the iPhone finally adopts a variable aperture lens. It’s still unclear whether this feature will be available across both iPhone 18 Pro models or just the Pro Max variant. Regardless, it’s expected to be exclusive to the main camera, not the ultra-wide or telephoto lenses.
On paper, this is significant news. In theory, a variable aperture lens allows users to adjust the depth of field. In practice, we shouldn’t get overly excited about achieving the effect shown in the lead image, and here’s why it might not change much.
The drawbacks
The primary limitation of iPhones isn’t necessarily the lens aperture — which is already fairly wide — but rather the size of the image sensor. As with most things, the larger the sensor, the shallower the depth of field achievable. Compared to DSLRs and mirrorless systems, iPhones have extremely small sensors, and this is unlikely to change this year.
With the same sensor size and only a marginally wider aperture, basic physics suggests we shouldn’t expect dramatic improvements.
The potential upside
Despite these limitations, there may be reasons for optimism. Integrating a mechanically variable aperture into one of the iPhone’s cameras is no simple feat — it’s both intricate and costly, especially given how compact smartphone lenses are.
This raises an important question: why would Apple invest in such complexity and expense for what we’d expect to be a fairly modest gain? If the improvement is merely what the math suggests, it doesn’t seem worth the effort.
This makes me wonder if — assuming Apple does indeed plan to highlight this feature in its marketing — there’s more to the story. One plausible theory is that the optical enhancement could serve as a backdrop for a substantial upgrade to Portrait mode. While the simulated effect has improved significantly each year, there’s still room for refinement, and perhaps the enhanced processing power of the new chip allows Apple to deliver a more convincing, natural-looking result.
If that’s the case, most users likely won’t mind that it’s somewhat of a workaround — the variable aperture offering only a minor benefit while software drives the real improvement. Ultimately, what matters to most people is the final output. That’s my best assessment so far.
Do you have a different theory? Share your thoughts in the comments below.
Photos: Ali Pazanil, Tamara Bellis, Kalen Emsley