Olympus E-520 vs Sony A7 III: An Exhaustive Comparison for Serious Buyers

In the era of rapid photographic technological advances, selecting the right camera - especially between two models from vastly different generations - requires more than just cursory glances at specs or marketing buzzwords. Today, we dive deep into a comparison between the Olympus E-520, an entry-level DSLR from 2008, and the Sony A7 III, a widely acclaimed professional mirrorless camera released in 2018. By dissecting their designs, technologies, capabilities across numerous photographic disciplines, and usability, this comprehensive guide seeks to empower photographers of various skill levels in making an informed choice aligned with their creative needs and budget.

First Impressions: Design, Build, and Ergonomics

When handling cameras daily, the tangible feel, control placement, and operational fluidity are as critical as pixel counts or autofocus points. The Olympus E-520, positioned as a compact SLR with a traditional DSLR form factor, contrasts starkly with Sony’s modern SLR-style mirrorless body of the A7 III.

Physical Size and Handling

At a glance, the E-520’s body measures 136 x 92 x 68 mm and weighs 552 grams, making it lightweight for a DSLR. Its pentamirror optical viewfinder and fixed 2.7-inch, low-res LCD reflect design norms from 2008. Meanwhile, the Sony A7 III measures 127 x 96 x 74 mm and comes in at 650 grams - slightly heavier, but much more compact considering the full-frame sensor inside. The A7 III benefits from a sturdier magnesium alloy body with weather sealing, a feature completely absent from the Olympus.

The top view comparison reveals a clear evolution in control ergonomics:

Where Olympus offers basic mode dials and modest button layouts, Sony’s top deck presents dual control dials, dedicated AF controls, and a customizable function button ecosystem that greatly enhances professional usability, particularly for fast-paced shooting.

Viewfinder and LCD Panel

Olympus’s optical pentamirror viewfinder offers 95% frame coverage and a 0.46x magnification, making composition and focus confirmation somewhat approximate. In contrast, the Sony A7 III sports a sharp electronic viewfinder (EVF) with 2359k dots resolution, near-perfect 100% frame coverage, and 0.78x magnification, providing a transparent preview of exposure, white balance, and focus before pressing the shutter.

On the rear, Sony’s 3-inch tilting touchscreen with 922k dots supports live view touch focusing and menu navigation, a vast improvement over Olympus’s fixed, non-touch, and much dimmer 230k-dot LCD. For those engaged in live view shooting or video, the A7 III offers far more comfortable framing and feedback.

Sensor Technology and Image Quality: The Heart of the Camera

Sensor Sizes and Resolution

The fundamental difference lies in sensor technology and size: Olympus’s E-520 uses a 10.0 MP Four Thirds CMOS sensor (17.3 x 13 mm), whereas the Sony A7 III features a 24.2 MP full-frame BSI-CMOS sensor (35.8 x 23.8 mm). Sony’s sensor area is almost four times that of the Olympus, conferring significant advantages in light gathering, dynamic range, and noise performance.

This is further quantified in DxOMark scores:

These metrics highlight that the A7 III can capture richer colors, retain more detail in shadows and highlights, and maintain usable image quality at much higher ISOs, indispensable for low-light or high-contrast scenarios.

Image Characteristics and Output

The Olympus E-520’s antialias filter reduces moiré but softens textures slightly, which was common at the time. Its Four Thirds aspect ratio of 4:3 may appeal to some, but standard print sizes often leverage 3:2 or 16:9 ratios like those Sony uses.

Sony’s A7 III utilizes a backside-illuminated sensor (BSI-CMOS), enabling better light efficiency, especially with modern lenses. The native ISO range extends from 100 to 51200, expandable to 50–204800, supporting extreme low light and astrophotography. Olympus tops out at ISO 1600 natively, limiting its capacity under dim conditions.

Autofocus Systems: Precision and Speed Across Genres

A key operational difference lies in autofocus (AF) system sophistication, which directly impacts success under demanding shooting styles.

The E-520’s modest 3 AF points and contrast-detection AF in live view reflect its entry-level status. During testing, its AF speed is adequate for portraits or landscapes but struggles with action requiring predictive tracking or seamless focus transitions.

In contrast, the Sony A7 III boasts a sophisticated 693-point hybrid AF system that covers nearly the entire frame, brilliantly locking onto subjects with quick and accurate eye and face detection, including for animals - a vital asset for wildlife photographers. Its continuous autofocus performance excels in sports and wildlife, especially combined with 10 fps continuous burst shooting.

Photography Disciplines Performance Breakdown

To provide practical insights, we examine each camera’s suitability across diverse photographic styles, taking into account real-world performance validated through field tests.

Portrait Photography

Portraiture demands faithful skin tone rendering, pleasing background separation, and precise eye focus.

• Olympus E-520 delivers solid skin tones with accurate color reproduction, but its limited resolution and smaller sensor yield less pronounced bokeh and less creamy background blur - especially with the Four Thirds crop factor of 2.1, restricting wide aperture lenses’ effectiveness.

• Its face detection AF helps in basic scenarios but might miss catchlight-perfect focusing in dynamic conditions.

• Sony A7 III provides exceptional tonal gradation, 24 MP resolution for exquisite detail, and superb subject-background separation through compatibility with fast full-frame lenses. Its eye AF feature consistently locks on real-time, a game-changer for studio or environmental portraits.

Landscape Photography

Landscape photographers prioritize dynamic range, resolution, and ruggedness.

• Olympus, with a 10 MP Four Thirds sensor, produces decent detail but is handicapped by narrower dynamic range and lower ISO performance. Lack of weather sealing makes it less viable for harsh outdoor use.
• Sony’s A7 III offers wider dynamic range (14.7 EV) and higher pixel count to extract fine detail and shadow separation. Its weather-resistant body is a boon in inclement conditions.

Wildlife and Sports Photography

High-speed subject tracking and telephoto lens compatibility are paramount here.

• Olympus supplies limited AF points and moderate burst rates (4 fps), insufficient for fast-moving wildlife or competitive sports. The crop factor and numerous compatible lenses (45 Four Thirds lenses) somewhat ease telephoto reach but can’t compensate for autofocus limitations.
• Sony’s A7 III excels with 693 AF points, eye and animal tracking, and a 10 fps burst rate, making it suitable for most demanding wildlife or sports applications. The vast Sony E lens ecosystem (121 lenses and counting, including excellent super-telephoto offerings) provides outstanding versatility.

Street Photography

Discretion, compactness, and rapid focusing matter.

• Olympus is physically slightly bulkier, with slower AF and lower sensitivity, although its smaller sensor and 4:3 aspect ratio can facilitate compositional creativity.
• Sony’s mirrorless design favors portability, silent shutter options (not available on Olympus), and fast, reliable AF, although the increased cost and learning curve might deter some.

Macro Photography

Critical factors include focusing precision, stabilization, and magnification ability.

• Olympus features sensor-based image stabilization, helpful for macro work by stabilizing minor shake, but lacks focus stacking or bracketing capabilities.
• Sony also boasts 5-axis in-body stabilization, which combined with precise focus peaking and touch-to-focus, offers better control over critical focusing. Compatibility with specialized macro lenses in the E mount ecosystem is excellent.

Night and Astrophotography

High ISO performance and manual control impact results here.

• Olympus’s max native ISO 1600 restricts use in dark environments; noise becomes pronounced beyond that ISO.
• Sony’s A7 III native ISO extends to 51200, with clean shadows and less noise, facilitative of night skies and low light scenes. Its longer max shutter speed of 30 seconds and remote control apps support advanced astro techniques.

Video Capabilities

Though Olympus E-520 lacks video recording functions entirely, Sony’s A7 III caters robustly to hybrid shooters.

• The A7 III supports 4K UHD (30p/24p) and Full HD slow-motion up to 120 fps, alongside microphone and headphone jacks - essentials for professional video workflows.
• Features like in-body 5-axis stabilization and advanced codecs (XAVC S) make the Sony far more versatile for multimedia creators.

Practical Considerations: Lenses, Battery Life, and Storage

Lens Ecosystems

• Olympus E-520 uses the Four Thirds mount, boasting some 45 lenses, mostly designed for older DSLR lenses. While glass options cover various focal lengths decently, the ecosystem’s vitality and innovation lag behind mirrorless systems.
• Sony A7 III leverages the thriving Sony E-mount with over 120 prime and zoom lenses from Sony and third-party manufacturers, including a wealth of modern, fast, native full-frame optics compatible with advanced features.

Battery Life and Storage

Despite its age, Olympus offers a respectable quoted battery life of 650 shots per charge, slightly edging Sony’s 610 shots, but modern shooting patterns with LCD/EVF usage tend to shorten actual endurance.

Sony’s more modern battery (NP-FZ100) and the camera’s dual SD card slots provide professional flexibility and redundancy, unlike Olympus’s single slot with Compact Flash and xD card compatibility - a limitation for fast data handling and convenience.

Connectivity

Sony shines with built-in wireless, Bluetooth, NFC, HDMI, and USB 3.1 Gen 1 for efficient tethering and media transfer. Olympus E-520 is limited to USB 2.0 and lacks wireless capabilities altogether, increasingly inconvenient in modern workflows.

Putting It All Together: Performance Ratings and Genre-Specific Scores

• Portrait: Sony leads with superior resolution and AF.
• Landscape: Sony’s enhanced dynamic range and weather sealing trump Olympus.
• Wildlife and Sports: Sony’s speed and tracking overshadow Olympus.
• Street and Travel: Sony’s smaller size and silent modes make it more street-friendly despite being slightly heavier.
• Macro: Both reliable; Sony edges due to stabilization.
• Night/Astro & Video: Sony dominates.

Sample Image Comparison

Olympus E 520 front Olympus E 520 screen back Sony A7 III front Sony A7 III screen back

Side-by-side sample comparisons reveal Sony’s superior image clarity, richness in shadow detail, and clean noise profile at higher ISOs, while Olympus images feel softer and less vibrant, though usable in well-lit scenarios.

Who Should Buy Which Camera?

Olympus E-520: Entry-Level Enthusiasts on a Budget

The E-520 caters primarily to beginners or hobbyists stepping into DSLR photography, especially those interested in basic portraiture, casual landscape, and general-purpose shooting where budget constraints exist. Its optical viewfinder, image stabilization, and intuitive exposure modes make learning fundamental photography straightforward.

However, limitations in sensor resolution, AF system, and lack of advanced features make it unsuitable for professionals or serious enthusiasts invested in demanding shooting scenarios or video.

Sony A7 III: The All-Round Professional Workhorse

Sony’s A7 III is a mature flagship - versatile for enthusiasts and professionals alike - excelling in all photography genres from portraits to wildlife and video. The rich lens ecosystem, advanced autofocus, superior sensor performance, and robust build offer unmatched value in the full-frame mirrorless category at its price. Its versatility also suits hybrid shooters balancing stills with high-quality video demands.

Final Thoughts

How do you navigate two cameras separated by a decade of innovation, layout philosophy, and technological leaps? The Olympus E-520 represents a venerable, affordable entry point into interchangeable lens photography with solid, straightforward features typical of circa 2008. In contrast, the Sony A7 III is a thoroughly modern, high-performance tool engineered for demanding professionals who need top-tier autofocus, image quality, and video.

Our hands-on testing confirms that the Sony A7 III outperforms the Olympus comprehensively across all critical parameters, justifying its significantly higher price point for serious photographers or content creators. Conversely, if budget and simplicity dominate your priorities, the Olympus remains a capable albeit modest companion.

For those ready to invest deeply in their craft or needing robust adaptability and current-generation features, the Sony A7 III is the clear recommendation.

Expert advice based on extensive hands-on evaluation, sensor testing, AF system trials, and field experience - empowering your next camera choice for years of creative fulfillment.