Panasonic GH5S vs Pentax 645D: A Detailed Comparison for the Discerning Photographer

When it comes to selecting a camera that aligns perfectly with your photographic aspirations and working style, understanding the nuanced distinctions between models is paramount. In this comprehensive comparison, we dissect the Panasonic Lumix DC-GH5S - a mirrorless powerhouse tailored for video professionals - and the Pentax 645D, a venerable medium format DSLR renowned for its image quality legacy in studio and landscape work. Each camera occupies a distinct niche in the photographic ecosystem; our goal is to transcend surface-level specifications and rigorously evaluate real-world performance across all major photographic disciplines. This detailed analysis emphasizes technical prowess, user ergonomics, system extensibility, and value-for-money considerations, grounded in extensive hands-on testing and years of industry expertise.

First Impressions and Ergonomics: Handling Two Different Cameras in Size and Style

The ergonomic experience sets the foundation for any camera’s usability over long shoots or demanding scenarios. Here, the GH5S and 645D present stark contrasts reflective of their design philosophies.

The Panasonic GH5S is a mirrorless camera with a traditional SLR-style body but in a relatively compact form factor: dimensions of 139 x 98 x 87 mm and a weight of 660g. This lightweight design engineers portability without sacrificing control heft. It fits comfortably in hand with well-placed grip contours suitable for extended handheld shooting. The build quality is robust, featuring environmental sealing - a significant boon for outdoor use.

Conversely, the Pentax 645D embraces a large-format DSLR footprint (156 x 117 x 119 mm, 1480g), almost twice the weight of the GH5S, emphasizing durability and presence for professional studio or landscape workflow. Its large grip and substantial build afford balance when paired with heavy medium format lenses but reduce its pocketability and quick-shoot potential. Environmental sealing is also present, affirming Pentax’s commitment to ruggedness.

Examining control layouts from the top reveals Panasonic’s modern approach, favoring customizable buttons and a fully articulating touchscreen facilitating intuitive operation, whereas Pentax’s rigid traditional pentaprism design provides fewer direct customizations and lacks touchscreen capabilities. The GH5S thus offers a more versatile and user-friendly control scheme for photographers who actively switch settings on the fly.

In summary, for travel and fast-paced scenarios, the GH5S’s ergonomic profile is superior, while the 645D excels in stability and control fidelity for deliberate, studio-style shooting, but at the cost of size and weight.

Sensor Technology and Imaging: A Tale of Two Formats and Their Impact on Picture Quality

The most foundational difference separating these cameras lies in their sensor designs and resultant imaging capabilities.

• The Panasonic GH5S sports a 17.3 x 13 mm Four Thirds CMOS sensor with 10 megapixels, exquisitely tuned for exceptional high-ISO performance and video-centric dynamic range, emphasizing sensitivity over resolution. Its lack of an anti-alias filter further sharpens detail rendition, albeit at a modest pixel count - a typical trade-off in video-focused systems. The sensor's relatively small area (224.9 mm²) imposes a 2.1x focal length multiplier on lenses, affecting field of view.

• The Pentax 645D is built around a gargantuan medium format CCD sensor measuring 44 x 33 mm with 40 megapixels of resolution, delivering unparalleled image detail and color fidelity with an area of 1452 mm² - roughly 6.5 times the size of the GH5S sensor. This leads to superior dynamic range (DxO mark 12.6 stops), deeper bit-depth color (24.6 bits), and impressive tonal gradations, which professionals cherish for landscape and studio photography. Its effective focal length multiplier is 0.8x (slightly less than full-frame), broadening lens perspectives.

Looking deeper, the GH5S’s native ISO sensitivity ranges from 160 to 51200, expandable up to ISO 204800, a specification extremely advantageous for low-light shooting and astro-photography, while the 645D caps at ISO 1600 with no boosted ISO, reflecting its sensor generation and the CCD architecture’s limitations under extreme sensitivity conditions.

Regarding raw file handling, the 645D produces massive raw files (~80MB) in 16-bit color depth, ideal for intensive post-processing, compared to the GH5S’s smaller yet highly malleable 10-bit raw output optimized for video pipelines.

Thus, landscape and studio photographers who require ultimate resolution and tonality lean heavily toward the 645D, while shooters prioritizing video, high-ISO stills, or fast action may find the GH5S’s sensor design more serviceable, despite lower resolution.

Autofocus Systems and Speed: Balancing Precision with Tracking Capabilities

The autofocus system provides critical insight into practical shooting scenarios, especially when capturing fleeting moments.

The Panasonic GH5S employs a contrast-detection autofocus system with 225 focus points, enhanced by advanced face detection and continuous autofocus modes. Although lacking phase detection pixels, in hands-on testing, this hybrid contrast AF performed admirably - particularly in video where smooth focus transitions are paramount, but occasionally slower in still autofocus acquisition compared to phase systems in good light.

Animal eye AF is absent on the GH5S, a feature increasingly standard in modern mirrorless cameras, which is a noted deficiency for wildlife photographers.

The Pentax 645D, with its DSLR heritage, features a traditional phase-detection AF system with only 11 focus points and no face detection or live view AF, limiting its AF flexibility. It operates reliably in bright conditions but struggles in low light and dynamic environments, making it less effective for fast-moving subjects.

Additionally, the GH5S supports high burst rates of 12 frames per second, supplemented by silent shutter modes at speeds up to 1/16000s, enabling discreet shooting, whereas the 645D’s mechanical shutter caps at a modest 1 fps and max shutter speed of 1/4000s, constraining action capture sufficiency.

In practice, for wildlife and sports photographers requiring rapid autofocus, versatility, and silent operation, the GH5S is clearly more capable, whereas the 645D’s AF utility is better reserved for static, well-composed subjects.

Displays and User Interface: Touchscreen versus Traditional LCD and Optical Viewfinder Experience

The GH5S’s 3.2-inch fully articulating touchscreen LCD at 1620k dots provides live view flexibility unmatched by the 3-inch fixed, non-touch TFT display (921k dots) on the 645D. This articulating screen facilitates shooting from challenging angles (low or high) and lends itself well to vlogging and video productions.

While the 645D offers an optical pentaprism viewfinder with 0.85x magnification and 98% coverage, Panasonic opts for a high-resolution (3680k dots) electronic viewfinder with 100% coverage and 0.76x magnification on the GH5S. This EVF advantage incorporates live exposure previews, focus peaking, and histogram overlays, all absent in the 645D’s OVF.

The interface on the GH5S includes extensive customization, intuitive menus, and touch focus capabilities that dramatically improve handling speed, particularly in complex shooting situations. The 645D adheres to a more traditional analog control scheme without illuminated buttons or touchscreen responsiveness, requiring a learning curve.

Overall, users accustomed to modern interfaces and video workflows will find Panasonic’s design far more compelling, while traditionalists may prefer the direct feedback and optical clarity of Pentax’s viewfinder system.

Performance Across Photography Disciplines: Real-World Use Cases Evaluated

Photography encompasses a broad spectrum of genres, each with distinct demands. Let’s explore how the GH5S and 645D perform across these major disciplines - with an eye toward actionable recommendations.

Portrait Photography

The GH5S’s 10MP sensor, coupled with its Micro Four Thirds native lenses, offers respectable skin tone rendition and smooth bokeh, helped by its absence of an AA filter. The excellent eye detection AF simplifies focus acquisition on subjects’ eyes, ensuring sharpness where it counts.

That said, the larger medium format sensor of the 645D renders portraits with a shallower depth of field and exceptionally nuanced tonal rendition, delivering exquisite skin textures and smooth highlight roll-offs prized by high-end portrait photographers.

Given their respective characteristics:

• GH5S shines when portability, fast AF, and continuous shooting matter for portrait sessions involving children or environments demanding mobility and speed.
• 645D excels for controlled, studio portraits requiring detail and tonal subtlety, albeit with slower AF and heavier gear to manage.

Landscape Photography

Landscape photography demands high resolution, extensive dynamic range, and weather-sealed reliability.

Pentax’s medium format 645D produces stunning 40MP images with a celebrated 12.6-stop dynamic range, capturing shadow details and recovering highlights with remarkable precision. This, combined with Pentax’s weather sealing, makes it ideal for outdoor landscape expeditions.

The GH5S, while only 10MP, offers excellent high ISO range, reduced noise, and weather sealing, making it versatile in less-than-ideal light or weather conditions. However, its smaller sensor limits its ultimate resolution and tonal gradations compared to medium format.

For landscape purists seeking the ultimate image quality, the 645D is the standout choice, but those prioritizing versatility, mobility, and effective low light handling should consider the GH5S.

Wildlife and Sports Photography

Due to the GH5S’s rapid 12fps burst, advanced continuous AF tracking, and high ISO capabilities, it clearly outpaces the 645D in action photography. Its smaller sensor and faster electronics facilitate noise-free performance at high frame rates.

The 645D’s single frame per second rate, relatively basic AF points, and limited shutter speed make it unsuitable for dynamic wildlife or sports shooting.

Street Photography

Street photographers often prioritize discretion, portability, and fast response.

The GH5S’s compact size, silent electronic shutter, and articulating touchscreen mark it as an excellent candidate for discreet street work, even under low light.

The large, heavy 645D is unwieldy for street shooting, lacks silent shutter, and requires deliberate setup, which limits candid captures.

Macro Photography

Macro requires precise focusing and camera stability.

Neither camera offers in-body image stabilization, which is a notable omission in the GH5S for macro handheld use, though its post-focus and focus stacking features present creative advantages.

The 645D, given its heavier body and traditional DSLR design, can pair well with dedicated macro lenses offering high resolution, but its slow AF makes handheld macro challenging.

Night and Astro Photography

The GH5S’s extraordinarily high ISO ceiling and excellent noise management secure its position as a preferred camera for night and astrophotography, especially with its electronic shutter facilitating silent, vibration-free shots.

The 645D’s limited ISO range restricts its utility in dark environments, but its medium format sensor provides notable dynamic range advantages in long exposures.

Video Capabilities

A core strength of the GH5S lies in video. Supporting:

• UHD 4K (4096x2160) at up to 60p with 10-bit 4:2:2 color over HDMI
• Internal recording supports multiple codecs including H.264 and H.265
• Microphone and headphone jacks enabling professional audio monitoring
• Advanced video tools like V-LogL profile and waveform monitors
• 4K PHOTO mode capturing 8MP images at 30 fps from video frames

The 645D, by contrast, offers no video capabilities, reflecting its design era and medium format heritage.

Hence, for creators whose work extends into professional video or hybrid multimedia, the GH5S is the clear frontrunner.

Travel Photography

Given the GH5S’s compactness, articulating screen, dual card slots with UHS-II support, and wireless connectivity (Wi-Fi, Bluetooth), it serves well as an all-in-one travel camera.

In contrast, the large and heavy 645D, with no wireless features and slower write speeds via dual SD (UHS-I) cards, demands more effort to travel comfortably.

Build Quality, Environmental Resistance, and Battery Life

Both cameras feature environmental sealing, a hallmark of professional-level gear, safeguarding against dust and moisture intrusion.

The GH5S benefits from a well-rounded build combined with a 440-shot battery life rating per CIPA standards, which - while not record-breaking - is respectable for mirrorless systems.

The 645D’s larger body accommodates a more powerful battery offering approximately 800 shots per charge, advantageous for extended shoots without battery swaps.

On storage, the GH5S supports dual SD card slots with modern UHS-II (V60) speed compatibility crucial for 4K video recording, and the 645D uses dual SD/SDHC slots (non-UHS-II), showing the GH5S’s edge in data handling speed.

Connectivity and Workflow Integration

GH5S is modern in connectivity, featuring built-in Wi-Fi and Bluetooth for seamless image transfer and remote shooting via Panasonic’s mobile apps.

The 645D offers no wireless options and connects via USB 2.0, which is considerably slower. These omissions may increase tethered workflow reliance and delay file offloading.

For professional workflows, the GH5S aligns with contemporary studio and field needs, while the 645D requires more traditional tethering setups.

Price-to-Performance and Lens Ecosystem

At launch, the GH5S retailed around $2500, whereas the 645D commanded a higher $4000 price point, reflecting its medium format status.

The GH5S benefits from the extensive Micro Four Thirds lens ecosystem, boasting over 100 native lenses from Panasonic, Olympus, and third parties, spanning wide-angle primes to high-end telephotos, including dedicated video lenses.

The 645D, limited to only six native Pentax 645 lenses available at the time, offers fewer options, and medium format lenses tend to be larger, pricier, and less versatile.

Thus, for budget-conscious buyers who prioritize lens variety and affordability, the GH5S affords more flexibility.

Real-World Samples and Image Quality Comparison

Panasonic GH5S front Panasonic GH5S screen back Pentax 645D front Pentax 645D screen back

Side-by-side evaluations illustrate the complementary strengths:

• The 645D’s medium format sensor reveals unrivaled detail resolution, dynamic range, and color depth in landscapes and studio shots - capturing subtle textures and colors impossible for smaller formats.
• The GH5S produces impressively clean images at high ISO, delivering punchy colors suitable for low-light event shooting and video frames but visibly reduced resolution for print-quality enlargements.
• Bokeh quality in portraits favors the 645D, catering to shallow depth of field, while GH5S’s video aperture choices and lack of AA filter preserve sharpness at smaller apertures.

Performance Ratings and Genre-Specific Analysis

To assist decision-making, performance scores summarize how each camera fares across technical and use-case parameters.

In overall capability, the GH5S earns high marks for video, low light, and speed, while the 645D excels in resolution and image fidelity but lags in autofocus and video.

• Portrait & Landscape: 645D leads due to sensor size and resolution.
• Wildlife & Sports: GH5S dominates with AF speed and burst.
• Street & Travel: GH5S favored for portability and silent shooting.
• Macro & Night: GH5S favored for high ISO and features.
• Video: GH5S exclusively provides pro-grade options.

Final Recommendations: Who Should Choose Which Camera?

Choose the Panasonic GH5S if you:

• Require a hybrid photo/video tool with professional 4K60p capture and quality audio features
• Shoot in low light or fast action scenarios with demanding autofocus capabilities
• Prioritize portability, high ISO performance, and a modern interface with touchscreen EVF
• Wish to leverage the extensive Micro Four Thirds lens ecosystem at reasonable costs
• Need weather-sealing in a smaller, lighter body suitable for travel and street photography

Choose the Pentax 645D if you:

• Prioritize ultimate image resolution and dynamic range for studio or landscape work
• Value medium format tonality and color fidelity for large prints or detailed commercial projects
• Are indifferent to video, fast autofocus, or compactness, focusing instead on image quality above all
• Have access to medium format lenses and workflows tuned to large-file handling
• Accept a heavier body and more traditional DSLR controls for assured reliability in controlled environments

Conclusion: A Comparison Bridging Different Eras and Genres

The Panasonic GH5S and Pentax 645D cater to distinct photographic paradigms with minimal overlap: the former representing a modern, video-capable mirrorless system optimized for speed and low light, the latter embodying the large-format tradition emphasizing max resolution and tonal quality. Informed choice depends heavily on your priorities - whether capturing ultra-high definition portraits or landscapes, or pursuing motion-rich events and multimedia content creation.

This side-by-side evaluation, enriched with firsthand insights and rigorous testing criteria, equips both enthusiasts and professionals to navigate this decision with clarity and confidence.

With meticulous analysis and decades-long hands-on expertise, we strive to empower your next camera investment with data-driven, practical knowledge.