Panasonic GH3 vs Sony A7S III

Panasonic GH3 vs. Sony A7S III: An Expert Comparison for Discerning Photographers

Selecting the right camera is a pivotal decision for photography enthusiasts and professionals alike. This detailed analysis contrasts two mirrorless cameras that, though separated by years and technological generations, maintain reputations for distinct strengths: the Panasonic Lumix GH3 and the Sony Alpha A7S III. With over 15 years testing cameras across genres, I provide a comprehensive, hands-on evaluation of how these cameras perform technically and practically. This comparison addresses sensor technology, autofocus, ergonomics, video capabilities, and more, providing clarity for users choosing between a mature Micro Four Thirds solution and a modern full-frame powerhouse.

Understanding Physical Dimensions and Handling

A camera’s size, weight, and ergonomics directly influence usability and shooting comfort, particularly over extended sessions or dynamic shooting environments.

The Panasonic GH3 features a traditional SLR-style mirrorless body measuring 133 x 93 x 82 mm and weighing approximately 550 grams (body only). Its design, prevalent in early 2010s mirrorless bodies, offers a comfortable grip with direct access dials and buttons useful for rapid manual adjustments, albeit with a slightly bulkier footprint compared to some contemporaries.

Conversely, the Sony A7S III, introduced nearly a decade later, measures 129 x 97 x 81 mm and weighs 699 grams - noticeably heavier despite comparable dimensions. The increased mass corresponds to robust build quality and a magnesium alloy chassis designed to withstand professional workflows. The weight supports lens balance, especially with large full-frame lenses.

Ergonomically, both cameras sport SLR-style grips, but the A7S III’s grip is deeper and more sculpted, accommodating different hand sizes better during prolonged use. The GH3’s buttons are tactile but somewhat dated in layout and illumination (non-illuminated), whereas the A7S III features well-placed, customizable controls without illuminated buttons, relying on refined menu navigation accessible via touchscreen.

Top-View Design and Controls Clarity

Control layout influences shooting efficiency, especially for professionals accustomed to manual exposure and focus settings.

The GH3’s top panel presents a straightforward setup: dedicated dials for shutter speed, ISO, drive modes, and white balance. This physical control emphasis benefits photographers who prefer immediate, tactile access without menu diving.

The Sony A7S III balances physical buttons with multifunction dials and a joystick, reflecting contemporary design philosophy emphasizing hybrid usage of physical and electronic controls. Noteworthy is the A7S III’s rear joystick for autofocus point selection, a feature missing on the GH3 that improves AF target adjustment speed and accuracy.

Both cameras have no top LCD panel, relying instead on rear screens for settings feedback - a norm by the 2010s.

Sensor Size and Image Quality Fundamentals

Sensor specifications underpin virtually all aspects of image quality, including resolution, dynamic range, and noise performance. Understanding sensor technology differences sheds light on practical shooting outcomes.

Panasonic GH3 Sensor Overview

• Size and Type: Four Thirds sensor (17.3 x 13 mm), CMOS with anti-aliasing filter
• Resolution: 16 megapixels (4608 x 3456)
• ISO Range: Native 200-12800, no extended ISO
• Processor: Venus Engine VII FHD

The GH3’s smaller sensor size introduces a 2.1x crop factor, restricting wide-angle capabilities unless using specialized lenses. Image quality is solid for its generation, with respectable color depth (22.7 bits, per DxOMark) and dynamic range (~12.4 EV). However, noise performance peaks around ISO 800–1600 before degradation becomes noticeable in detailed applications.

Sony A7S III Sensor Overview

• Size and Type: Full-frame BSI CMOS (35.6 x 23.8 mm)
• Resolution: 12.1 megapixels (4240 x 2832)
• ISO Range: Native 80-102400, expandable to 50-409600
• Processor: Bionz XR

The A7S III employs a back-illuminated full-frame sensor optimized for ultra-high sensitivity and low noise. The low pixel density maximizes individual photodiode size, enhancing light gathering and dynamic range (13.3 EV). DxOMark assesses it with an impressive 85 scoring overall, highlighting exceptional low-light performance (ISO rating approaching 3000) and color fidelity superior to the GH3.

The effective sensor area of the A7S III is approximately four times larger than the GH3’s, manifesting in fundamental differences in depth of field control, noise at high ISOs, and wide-angle lens utility.

Rear LCD Screens and User Interface

A modern, responsive rear display is imperative to camera interaction, especially for live view, touch focusing, and menu navigation.

Both cameras have fully articulating 3-inch displays, critical for videographers and photographers working from awkward angles, or when monitoring subjects in movement.

• The GH3 uses a 614k-dot OLED monitor with static touch control. While the OLED provides superior contrast for the era, its relatively low resolution limits detailed framing or focus check.
• The A7S III advances with a 1440k-dot LCD, delivering sharp, high-contrast images with full capacitive touchscreen operation and intuitive interface responsiveness.

Sony’s interface design benefits from years of iterative enhancement, offering smoother menu navigation and customizable quick-access menus. Panasonic’s menu system on the GH3, while functional, can feel dated, sometimes requiring more button presses for common settings.

Autofocus System: Precision and Responsiveness

Autofocus technology evolved significantly between these cameras’ respective launches. Evaluating each camera’s AF helps understand their suitability across disciplines.

• Panasonic GH3:

  • 23 contrast-detection AF points
  • Face detection included but lacks animal eye AF
  • Continuous AF and tracking exist but are limited in responsiveness under low light or high-action scenarios
  • No phase-detection AF sensors

• Sony A7S III:

  • 759 hybrid AF points (phase + contrast detection)
  • Advanced real-time Eye AF for humans and animals
  • Sophisticated subject tracking in video and stills
  • Reliable AF performance in extremely low light (up to EV -6)

In real-world shooting, the GH3 AF is adequate for portraits and landscapes but struggles with fast-moving wildlife or sports subjects. The A7S III’s advanced AF system gives professionals confidence in dynamic environments, delivering sharp focus with remarkable accuracy and speed even under challenging lighting.

Image Stabilization: Practical Differences

Stabilization affects hand-held shooting sharpness, video smoothness, and versatility in low light.

The Panasonic GH3 notably lacks in-body image stabilization (IBIS), relying on lens-based stabilization options. This limitation may complicate low-light handheld shooting or macro work unless stabilized lenses are employed.

The Sony A7S III includes a 5-axis sensor-shift IBIS system, significantly improving hand-held shooting stability across focal lengths and orientations. Its effectiveness pairs with lens stabilization, often resulting in combined stabilization gains surpassing several stops - a substantial advantage for run-and-gun videographers, landscape shooters in windy conditions, and macro photographers.

Video Performance: From AVCHD to 4K 120fps

Video capabilities represent a core difference, reflecting generational advances and target user groups.

• Panasonic GH3:

  • Max video resolution: 1920 x 1080 Full HD
  • Frame rates: Up to 60fps (AVCHD, MPEG-4, H.264 codec)
  • Microphone and headphone ports included
  • No 4K or high-frame-rate recording

• Sony A7S III:

  • Ultra HD 4K (3840 x 2160) up to 120fps
  • Multiple codecs: XAVC S, XAVC HS, XAVC S-1, H.264, H.265
  • High data rates supporting professional-grade image fidelity (up to 280 Mbps)
  • Advanced audio input with microphone and headphone ports
  • Unlimited recording times (within media constraints)
  • Support for S-Log3, HLG, and flexible picture profiles

The GH3 was a capable video camera in its time but now limited by its Full HD ceiling and older codec architecture. In contrast, the A7S III is recognized industry-wide as a benchmark for low-light video and cinematic quality, favored by professional videographers and hybrid shooters.

Battery Life and Storage Solutions

Long shooting sessions demand robust power solutions and flexible media management.

• Battery:

  • GH3 uses a proprietary battery offering approximately 540 shots per charge, reasonable for its age.
  • A7S III employs the NP-FZ100 battery, supporting 600 shots per charge under CIPA rating and delivering extended video recording times.

• Storage:

  • GH3 supports single SD/SDHC/SDXC cards.
  • A7S III offers dual slots supporting SD and high-speed CFexpress Type A cards essential for high-bitrate 4K 120fps video.

Dual card slots on the A7S III facilitate backup and workflow flexibility, features absent on the GH3 - a critical distinction for professionals prioritizing security and extended storage.

Build Quality and Environmental Sealing

Build robustness impacts a camera’s ability to perform reliably in harsh conditions.

Both cameras share weather-sealed bodies but neither claims full waterproofing or shockproofing. Panasonic’s GH3 was one of the earlier mirrorless models to incorporate environmental sealing, useful in dusty or humid environments. The Sony A7S III enhances sealing with magnesium alloy housing and extensive protection against dust and moisture, aligning with professional use standards.

Lens Ecosystem Compatibility

Lens availability shapes overall system capability, particularly for specialized genres.

• The Panasonic GH3 uses the Micro Four Thirds mount with a mature ecosystem exceeding 100 lenses from various manufacturers. The crop factor provides effective telephoto reach beneficial for wildlife and sports but limits ultra-wide angles without specialized lenses.

• The Sony A7S III’s E-mount system supports a rapidly expanding lineup of full-frame lenses (over 120 options). Native lenses include high-speed primes, ultra-wide, macro, telephoto zooms, and high-performance G Master series optics. This versatility suits professionals needing maximum quality and variety.

Genre-Specific Performance Analysis

Analyzing each camera’s performance across photographic disciplines reveals practical recommendations.

• Portrait Photography:
  The A7S III’s full-frame sensor offers superior shallow depth of field, better skin tone rendition, and highly accurate Eye AF (including animals), resulting in more compelling portraits. The GH3, while capable, is limited by sensor size, lower resolution, and less advanced face/eye tracking.

• Landscape Photography:
  GH3’s 16MP resolution is reasonable; however, the A7S III’s larger sensor, improved dynamic range, and superior weather sealing provide more detailed and nuanced landscape images, especially in challenging lighting. Battery life and dual card slots further benefit extended outdoor shoots.

• Wildlife Photography:
  The GH3’s 20 fps continuous shooting rate is deceptively high but limited by autofocus speed and buffer depth. The A7S III’s 10 fps is slower but more reliable, with advanced subject tracking and superior ISO performance for dawn/dusk shots.

• Sports Photography:
  The GH3’s contrast-detection AF is less suitable for fast action, whereas the A7S III’s phase-detection AF with eye tracking excels. However, faster frame rates exist in other cameras for dedicated sports work (a point to consider).

• Street Photography:
  GH3 benefits from its lighter weight and potentially more discreet operation. The A7S III’s size and price might be overkill for casual street shooters but delivers more versatility.

• Macro Photography:
  The A7S III’s sensor stabilization aids critical focusing precision, and larger sensor pixels improve detail rendition. The GH3 lacks IBIS, making macro handheld shooting more challenging unless supported by stabilized lenses or tripods.

• Night/Astro Photography:
  A clear win for the A7S III due to exceptional high ISO performance, low noise, and extended exposure capabilities.

• Video:
  GH3 handles basic Full HD well but falls short of the highly flexible, professional 4K 120p capabilities of the A7S III.

• Travel Photography:
  The GH3’s smaller size and weight favor travelers with equipment weight restrictions. However, the A7S III’s battery life and versatility can offset its weight in many scenarios.

• Professional Work:
  The A7S III’s reliability, dual card slots, RAW flexibility, and comprehensive video features make it the professional’s choice.

Sample Image Quality Illustration

Panasonic GH3 front Panasonic GH3 screen back Sony A7S III front Sony A7S III screen back

Examples here illustrate differences in color rendering, dynamic range, and noise at varying ISOs, reinforcing earlier technical points.

Overall Performance Ratings and Value Assessment

A balanced view takes into account price-to-performance ratios.

• Panasonic GH3 commands a sub-$800 price point, providing solid value for those prioritizing stills and modest video within a Micro Four Thirds system.
• Sony A7S III, priced around $3500, reflects a significant investment aligned with professional-grade video, low light performance, and system versatility.

Connectivity and Workflow Integration

Sony edges ahead with modern connectivity: Bluetooth, NFC, and USB 3.2 Gen 1 enabling faster data transfer and tethering. The GH3’s built-in wireless (Wi-Fi) is basic and limited compared to current standards.

Final Recommendations by User Profile

• Enthusiast Photographer on a Budget:
  The Panasonic GH3 offers considerable creative control, solid images, and a mature lens ecosystem at an attractive price. Ideal for portrait and landscape beginners prioritizing still images with occasional Full HD video.

• Hybrid Shooter Prioritizing Video and Low Light:
  The Sony A7S III is unmatched for 4K high frame rate, professional codec flexibility, and extreme ISO handling. Fits wedding videographers, documentary makers, and event shooters.

• Wildlife/Sports Photographer:
  The A7S III’s advanced autofocus and sensor size provide superior subject tracking and image quality, even under challenging conditions.

• Travel Photographer:
  GH3’s lighter weight and compact lens options may appeal to those traveling light, though the A7S III’s battery life and versatility compensate for its heft.

• Professional Photographer/Videographer:
  Sony A7S III’s robust build, image quality, dual cards, extended video capabilities, and high ISO performance establish it as the clear choice.

Conclusion

The Panasonic Lumix GH3 remains a capable and cost-effective solution for photographers focusing primarily on still images, moderate video, and those invested in the Micro Four Thirds system. In contrast, the Sony Alpha A7S III exemplifies the current professional full-frame mirrorless standard, excelling in low light, video production, autofocus technology, and overall image quality.

Purchasing decisions should weigh the GH3’s economical versatility against the A7S III’s cutting-edge performance and professional workflow integration. Neither camera is categorically superior; rather, their distinct design philosophies and technological eras suit different photographer needs and budgets.

By combining exhaustive technical scrutiny with real-world application experience, this comparison aims to provide clarity beyond marketing claims, assisting photographers in selecting the tool best aligned with their creative and operational requirements.