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Received February 26 2024, accepted March 4, 2025, date of publication April 9, 2025.

Original Research Article

Discussing the Clinical Value of Full-Range Autofocus 
Endoscopic Cameras

Rongjiao Zhao1,* and Cong Yang2

1 Hangzhou Micro Intelligent Technology Co. Ltd., Zhejiang Hangzhou, China.
2 Jinan Micro Intelligent Technology Co. Ltd., Shandong Jinan, China.

* Corresponding Author Email: 378454121@qq.com

ABSTRACT

Objective: This study aims to explore the potential of full-range autofocus (FAF) technology to improve image clarity and 
operational ease in endoscopic procedures.

Methods: The paper analyzes the application and development of manual focus, autofocus, manual zoom, and auto zoom 
technologies in clinical endoscopy. The clinical value of FAF technology in endoscopy, including intelligent scene linkage and 
continuous optical lossless zoom, is discussed.

Results: The application of FAF technology significantly enhances medical diagnosis and treatment by providing clearer 
and more flexible imaging. This technology allows for seamless focusing from near to far distances, improving the accuracy and 
effectiveness of medical procedures.

Conclusions: The FAF technology represents a significant advancement in endoscopic technology. It not only improves 
diagnostic precision and treatment efficiency but also contributes to safer and more comfortable medical services, which can 
promote further development in the medical industry.

Keywords—Manual focus, Autofocus, Manual zoom, Auto zoom, Full-range autofocus.            

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Zhao, Yang: Discussing the Clinical Value of Full-Range Autofocus Endoscopic Cameras

J Global Clinical Engineering Vol.7 Issue 2: 2025 6

INTRODUCTION

In recent years, the medical endoscopic camera sys-
tem—integration of traditional optical technology with 
modern computer and microelectronics technologies—has 
become a widely utilized medical instrument because of 
increased medical standards and public health aware-
ness.1 These systems have become increasingly common 
in clinical diagnosis and treatment, significantly enhanc-
ing diagnostic and therapeutic accuracy, reducing patient 
suffering, and accelerating recovery.

A review of related research reveals that the primary 
goal of endoscopic camera systems is to assist doctors in 
“seeing clearly” by obtaining sharp images while maintaining 
user-friendliness and simplicity. Thanks to advancements 
in focusing and zooming technologies, endoscopic cameras 
have evolved from “manual focus to autofocus, manual 
zoom to auto zoom, and then to full-range autofocus (FAF),” 
thus greatly facilitating clinical procedures, ensuring the 
clear vision, reducing surgical risks, improving surgery 
success proportions, and enhancing the functionality and 
application experience of endoscopes.

This process not only marks technological advancement 
but also reflects the broader trend in medical equipment 
development toward efficiency, precision, and ease of 
use. The primary objective of this study is to analyze the 
application of autofocus and zoom technologies in en-
doscopes, and discuss their positive impacts on medical 
diagnosis and treatment. Furthermore, we explore the 
potential future influence of these technologies on the 
development of endoscopic technology.

TECHNOLOGICAL EVOLUTION IN ENDOSCOPIC 
FOCUSING 

Clinical Requirements for Imaging Precision

Endoscopic surgery is intricate and complex, requiring 
clear imaging to present the details of the observation area 
to improve the diagnosis proportion of lesions (especially 
early and subtle lesions), thereby facilitating the doctor’s 
surgical intervention. For example, when doctors perform 
gastrointestinal surgery, to prevent unnecessary damage 
caused by intestinal adhesion, clear images of the lesion 
are required. This clarity aids doctors in observation and 

operation, reducing the risks associated with the blindness 
of traditional surgery, and minimizing organ damage and 
functional interference.

Manual Focus 

In order to ensure a clear field of view in usage sce-
narios, medical endoscopic cameras initially introduced 
manual focus technology. This technology requires the 
operator to rotate manually the focusing ring based on 
visual judgment. The focusing effect heavily depends on 
the operator’s subjective judgment and precise adjust-
ment, demanding a high level of skill from the operator. In 
practice, human errors are inevitable, making it difficult 
to guarantee clarity, and the operation process generally 
takes about 3 seconds or even more. 

Autofocus                     

In medical scenarios, doctors often need to obtain the 
clearest images as quickly as possible. Therefore, with the 
development of electronic technology, autofocus technol-
ogy has been introduced into endoscopic cameras. This 
technology uses sensors to detect the distance between 
the target scene and the lens, automatically adjusting the 
focus. Operators only need to click a button on the cam-
era, and the lens will automatically adjust to the clearest 
image based on image clarity and the theoretical focus 
position, significantly simplifying the use of endoscopes 
and making them highly suitable for medical applications.

The principle of autofocus is as follows: Optical signals 
received by the integrated optical lens are transmitted to 
the image sensor module, where the image sensor inside 
converts the optical signals into electrical signals that are 
then sent to the camera’s processor. The processor runs 
an autofocus algorithm that controls an internal motor 
to execute the focusing operation.

The autofocus algorithm first filters the input image at 
the current motor position to reduce noise interference, 
and then enhances brightness through gamma correction. 
It then segments the image and calculates high-frequency 
information to characterize image clarity, adjusting the 
motor position based on the rate of clarity change. As the 
motor position changes, the mechanical distance matched 
by the optical lens group changes, thereby achieving the 



7 J Global Clinical Engineering Vol.7 Issue 2: 2025

Zhao, Yang: Discussing the Clinical Value of Full-Range Autofocus Endoscopic Cameras

focusing effect. This cycle continues until the clarity is 
maximized, at which point focusing is complete. An il-
lustrative diagram of the autofocus algorithm is shown 
in Figure 1.

 

FIGURE 1. Schematic diagram of the autofocus algorithm start-up.

Zoom Technology: From Mechanical to Liquid Lens 
Solutions

Constraints of Fixed Focal Length

The difference between “fixed focus” and “zoom” lies 
in the variability of the focal length. Fixed focus means the 
focal length is fixed, and clear focus can only be achieved at a 
certain distance; zoom means the focal length is adjustable, 
and the magnification of the zoom lens can vary.2 Initially, 
most endoscopic cameras adopted a “fixed focus” design.

Owing to the larger focal length resulting in a smaller 
field of view, different fixed-focus lenses typically have 
their respective usage scenarios. For example, ear, nose, 
and throat (ENT) and gynecology endoscopes commonly 
use a focal length of F14, as doctors prefer to observe 
smaller and more comprehensive images; urology often 
uses a focal length of F22; images from a focal length 
of F28 are more popular in thoracic surgery and some 
laparoscopic surgeries; while a focal length of F32 is 
the most common one in major abdominal surgeries. 
Therefore, although the advent of autofocus technology 
can provide doctors with a convenient and rapid focusing 

experience, fixed-focus cameras can only focus at a 
specific distance and cannot be adjusted. Clinically, it is 
still necessary to equip multiple fixed-focus mounts, such 
as F14, F22, F28, F32, etc., to meet the needs of different 
departments for different depths and field sizes, limiting 
the application of endoscopes in complex surgeries.

Zoom has always been a clinical challenge.3 Endoscopic 
zoom lenses were developed to address this issue. Zoom 
lenses can change the focal length by moving the internal 
optical components, thus changing the field of view through 
“zooming”. A single “zoom” lens equates to an integration 
of multiple “fixed-focus” lenses. When using a zoom lens, 
there’s no need to switch between different fixed-focus 
lenses, as the clearest image is obtained at any position 
within a certain distance by operating the zoom. Now the 
zoom technology is divided into manual zoom and auto zoom.

Manual Zoom

Manual zoom is primarily achieved through detachable 
optical zoom adapters. By manually adjusting the optical 
adapter, the internal optical lens group is altered, achieving 
zoom.4 While manual zoom cameras are more flexible than 
fixed-focus cameras, they still fall short in meeting the fast-paced 
and high-precision requirements of medical environments.

Auto Zoom

Owing to the precision required in surgical interventions, 
auto zoom systems must be miniaturized,5 structurally 
simple, and compact, and must meet image quality 
requirements. With the continuous development of 
camera technology, particularly in liquid lenses, auto 
zoom endoscopic cameras have started to emerge. Liquid 
lenses use specific control methods to adjust the refractive 
index or shape of the lens, offering a novel approach to 
zooming. These lenses are characterized by fast zoom 
response times, low power consumption, and noise-free 
operation, which distinguish them from traditional lenses.2 
They offer the benefits of low manufacturing costs, simple 
structure, and easier miniaturization.6

The principle of auto zoom involves electrowetting, 
which manipulates the liquid’s wetting properties via an 
electric field, thereby altering its shape and curvature. A 
liquid lens contains two immiscible liquids—nonconductive 



Zhao, Yang: Discussing the Clinical Value of Full-Range Autofocus Endoscopic Cameras

J Global Clinical Engineering Vol.7 Issue 2: 2025 8

FIGURE 3. Schematic diagram of liquid lens in energized state.

FIGURE 4. Schematic diagram of FAF workflow.

THE APPLICATION OF FULL-RANGE AUTOFOCUS 
TECHNOLOGY IN CLINICAL PRACTICE

The FAF technology, which integrates the advantages of 
both autofocus and zoom, has significantly enhanced the 

oil and a water solution—separated by an interface. By 
applying voltage across the interface, the lens curvature 
can change in tens of milliseconds, altering the focal 
length. Increased voltage increases lens curvature and 
optical power.7 Figures 2 and 3 show the liquid lens in 
de-energized and energized states, respectively. Liquid 
lenses, particularly those utilizing electrowetting, offer a 
tunable focal length by adjusting the curvature of a liquid 
surface.8 These lenses have been successfully incorporated 
into zoom systems, such as the design by Park and Park,9 
which utilized liquid lenses to achieve variable focal 
lengths for compact mobile cameras. Moreover, recent 
developments have seen the combination of liquid lenses 
with other optical elements to enhance zoom capabilities 
without the need for moving parts, as demonstrated in the 
continuous zoom systems for telescopes by Jiang et al.10 
Additionally, stabilizing mechanisms for liquid lens-based 
zoom systems have been explored to improve precision 
and reliability, as discussed in the four-group zoom system 
proposed by Li et al.11 Figure 4 shows the step-by-step 
workflow of FAF technology, from image capture to 
focus adjustment, and finally to image clarity feedback.

FIGURE 2. Schematic diagram of liquid lens in de-energized state.



9 J Global Clinical Engineering Vol.7 Issue 2: 2025

Zhao, Yang: Discussing the Clinical Value of Full-Range Autofocus Endoscopic Cameras

field of medical endoscopy, particularly in clinical diagnosis 
and treatment. This technology enables continuous focusing 
from near to far distances, significantly improving the 
imaging quality and flexibility of endoscopes, providing 
doctors with clearer and more comprehensive views, and 
profoundly impacting disease diagnosis and treatment.

First, the technology enables continuous zoom across 
multiple focal lengths, from F14 to F32, facilitating one-click 
switching between distant, medium, and close-up views. 
The camera system can achieve intelligent scene linkage; 
by setting focal lengths for different surgical scenarios in 
the endoscope’s control system, the camera automatically 
adjusts to the most appropriate and effective focal length 
for the scenario. A single FAF camera can seamlessly switch 
between focal lengths of F14 and F32, accommodating 
the usage habits of doctors across various departments.

Second, traditional endoscopy faced limitations in deep 
scene imaging, restricting doctors’ ability to observe lesion 
areas. The FAF-equipped endoscopes achieve optical, lossless 
continuous zoom, allowing for undistorted magnification 
and direct observation of suspicious areas without losing 
detail. Compared to traditional digital magnification, this 
method offers superior magnification, lossless images, 
and reduced noise, effectively resolving issues with 
“extremely small” lesions, such as tiny blood vessels and 
outlines, improving visual precision. This is particularly 
crucial for early detection, such as during gastrointestinal 
examinations, where FAF can enhance the detection of minor 
abnormalities in the mucosa, increasing early cancer detection 
rates and the identification of other serious conditions.

Moreover, the FAF technology can be combined with 
auto zoom to achieve one-click autofocus. This ensures 
precise focusing with minimal margin for error, faster and 
more accurately than traditional manual focus methods. 
This enhances surgical efficiency and reduces the risks 
associated with inaccurate focusing, thus making surgeries 
more precise and improving the clinical experience.

 Additionally, the application of FAF technology greatly 
improves patient comfort. In traditional procedures, frequent 
adjustments to the endoscope’s position to achieve clarity 
can cause patient discomfort. However, FAF reduces the 

need for frequent positional adjustments, decreasing 
patient discomfort and enhancing patient satisfaction.

Finally, this technology offers greater opportunities for 
medical research and education. High-definition, full-range 
images allow researchers to closely observe and record disease 
progression, which is essential for studying mechanisms 
of medical diseases and developing new treatments. 
These high-quality images also serve as educational 
resources, assisting medical students and young doctors 
in understanding the characteristics of various diseases.

CONCLUSION

Considering the current research and development 
trends in endoscopic devices,1 there is a growing prefer-
ence for miniaturization to enhance the safety and comfort 
of endoscopic procedures.8 Furthermore, with the future 
deep integration of artificial intelligence (AI)12 and ma-
chine learning (ML) technologies, the autofocus and zoom 
systems of medical endoscopic cameras are expected to 
achieve greater levels of intelligence and automation. 
This could include real-time image analysis, predictive 
focusing, and automatic adjustment of parameters to 
meet the constantly changing requirements of the surgical 
field. These innovations will continue to improve image 
quality during procedures, providing doctors with more 
intuitive and effective tools for surgery.

AUTHOR CONTRIBUTIONS

Conceptualization, R.J.Z.; Methodology, R.J.Z.; Writ-
ing–Original Draft Preparation, R.J.Z.; Writing–Review & 
Editing, R.J.Z. and C.Y.; Project Administration, R.J.Z.

ACKNOWLEDGMENTS
The research team acknowledges the optical engineer 

Mr. Guo for his advice and assistance in the construction 
of the experimental platform for valuable input on de-
veloping this paper.

FUNDING
This research received no external funding.

DATA AVAILABILITY STATEMENT
Not applicable.



Zhao, Yang: Discussing the Clinical Value of Full-Range Autofocus Endoscopic Cameras

J Global Clinical Engineering Vol.7 Issue 2: 2025 10

CONFLICTS OF INTEREST
The authors declare they have no competing interests.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE
Not applicable.

CONSENT FOR PUBLICATION
Not applicable.

FURTHER DISCLOSURE
Not applicable.

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