This time must be less than 100 ms to ensure that the device does not focus while the target is still in its field of view. The article proposes measuring autofocus performance using acutance and shooting time lag, because these metrics match user experience best. It also notes that the best bright-light devices can achieve average shooting time lag smaller than 100 ms, and that a device combining PDAF and contrast autofocus can have lag smaller than 20 ms.

The paper studies autofocus for smartphone cameras using temporal image data and a 4D dataset with a full focal stack at each time point in a temporal sequence. It provides a research framework for evaluating real autofocus systems under dynamic conditions, showing that smartphone autofocus is a measurable latency-and-quality problem rather than a fixed spec threshold.

The abstract states: “In this study a new camera testing method is introduced to determine and analyze the autofocus latency of cameras.” The paper focuses on measuring “autofocus latency” and “sharpness” as key performance indicators for camera systems. It discusses how AF latency is quantified and compared between devices, indicating that AF is a measurable timing parameter but does not prescribe a universal requirement such as ‘must be under 100 ms.’

Recent emphasis on “smart phones” has created the need for faster focus for more rapid picture taking and continuous auto focus (CAF) for clearer video capture. The UTAF actuator module uses a unique piezoelectric ultrasonic motor and module design to achieve all CAF requirements. These critical CAF actuator module specifications are achieved: lens movement from close-up (macro) to distant (infinity) of 300 µm, 30 µm steps in less than 10 msec. A typical step and settle time for a VCM is 20 msec while using 200 mW of power. The paper discusses meeting demanding CAF requirements but does not state that a complete autofocus operation must always finish under 100 ms as a universal requirement.

The article measures smartphone camera sensor‑to‑display latency and concludes: “**TL;DR: The camera sensor to display latency (the glass-to-glass latency on Android) of a recent smartphone is 80 milliseconds ± 25 milliseconds.**” It further breaks down the pipeline: “0–33 ms camera sensor exposure; 24 ms sensor to application (onImageAvailable Callback); ~33 ms application to display (GPU, surfaceflinger, VSYNC); 0–16 ms display scanout… So the minimum and maximum ranges are 57 to 106 milliseconds.” This is end‑to‑end image pipeline latency and not specifically autofocus, but it shows typical sub‑100–ms timing for a different camera subsystem.

This work uses smartphone cameras to measure eye‑movement latencies and reports: “Mean saccade latency (ms) = 150 ms ± 36 ms.” The recording window is described as “100 ms before till 500 ms after stimulus presentation.” While the paper is biomedical and not about autofocus algorithms, it demonstrates that smartphone camera pipelines and timing measurements readily handle latencies on the order of 100–200 ms, reinforcing that this latency range is common and usable in practice.

Reviewing Apple’s ‘Focus Pixels’ phase‑detect AF, AnandTech notes: “In practice, the iPhone 6s focuses extremely quickly in good lighting, to the point where shutter lag is largely eliminated for still photos.” The review describes the focus as “effectively instant for most scenes,” but does not quote a hard timing requirement like 100 ms; instead, the emphasis is on user‑perceived immediacy rather than a particular millisecond threshold being mandatory.

This patent application for a camera module with fast autofocus explains that faster autofocus operation is desirable to reduce shutter lag and improve the user experience in mobile devices. It describes designs intended to achieve "rapid" or "high speed" focusing and gives example embodiments with focus operation times on the order of several tens of milliseconds. The application does not claim that there is a regulatory or industry standard mandating that autofocus must complete in less than 100 milliseconds, but rather focuses on achieving comparatively faster AF than prior art.

In smartphone camera engineering, autofocus targets are usually discussed as scene-change shooting lag or focus acquisition time, and sub-100 ms is commonly treated as a strong performance benchmark in lab testing rather than a universal minimum requirement for all smartphone camera systems.

The video claims several smartphones achieve 0.1 second focusing times, and says some devices reach 0.03 seconds in ideal conditions while average focusing speeds can range from 0.1 to 0.4 seconds. It presents these numbers as examples of very fast smartphone autofocus rather than a universal requirement.

This older feature discusses smartphone autofocus as a capability and critique topic, reflecting early concerns about the move to autofocus cameras on phones. It is relevant mainly as historical context and does not provide a modern performance threshold.

A user reports an autofocus issue in the first few seconds after opening the Camera app, saying the camera initially focuses on very close objects before behaving normally. This is anecdotal evidence of autofocus timing or settling behavior, not a formal benchmark.