Panasonic S5 vs Pentax 645Z: A Hands-On Expert Comparison for Discerning Photographers

Choosing the right camera ultimately depends on your photographic goals, workflow needs, budget, and genre of interest. Having tested both the Panasonic Lumix DC-S5 and Pentax 645Z extensively in various real-world scenarios, I want to distill their key differences, strengths, and compromises to help you make a well-informed decision fitted to your style.

Both cameras are professional-grade workhorses, but they really exist at different ends of the imaging spectrum - one a compact full-frame hybrid powerhouse, the other a medium-format titan built for image quality perfection. I’ll guide you through everything from size and ergonomics, sensor technology, autofocus performance, all the way to specialized use cases like landscapes, wildlife, or video.

Let’s start by examining the physical form factors and controls.

Size, Handling, and Controls: Touring the Cameras’ Physical Impression

When I first picked up the Panasonic S5 and the Pentax 645Z side-by-side, the difference in size and weight was glaring, but in a way that reflects their intended purposes.

The Panasonic S5 is compact and versatile, weighing just 714 grams with a streamlined SLR-style mirrorless body measuring 133 x 97 x 82 mm. For a full-frame sensor camera, its small footprint lends itself well to discrete shooting and prolonged handheld use. Its solid build includes weather-sealing suitable for light rain and dusty environments.

On the other hand, the Pentax 645Z stands as a heavyweight champion of medium-format DSLR cameras, tipping the scales at a formidable 1,550 grams and measuring 156 x 117 x 123 mm. The larger body houses a robust weather-sealed magnesium alloy chassis designed for demanding environments - dustproof and freezeproof, capable of enduring harsh shoots in cold weather with no performance hit. You feel a sense of rugged durability but also acknowledge that it’s a camera more comfortable on a tripod or carried in a larger bag.

Control layout further underscores their distinct philosophies. The Panasonic S5, with an electronic viewfinder and fully articulating touchscreen, offers a modern tactile interface optimized for both stills and video shooters. Its illuminated buttons, customizable dials, and menu system lend fast adaptability - traits I found invaluable when switching between shooting disciplines.

The Pentax 645Z favors a traditional DSLR user experience with an optical pentaprism viewfinder offering 98% coverage and straightforward, no-frills button placement - notably absent a touchscreen. While it sacrifices some modern ease-of-use features, it excels for photographers who prefer tactile dials and optical monitoring for critical composition.

For travel and handheld shooting, the Panasonic S5 is the far more ergonomic and lighter choice, while the 645Z comes into its own for studio, landscape, and controlled environment shoots demanding the utmost stability and reliability.

Sensor Technology: Megapixels, Medium Format vs Full-Frame

A crucial factor separating these two is sensor size - one that fundamentally changes the character and quality of images.

The Panasonic S5 features a 24-megapixel full-frame sensor sized at 35.6 x 23.8 mm, an area of about 847 mm². It lacks an anti-aliasing filter, allowing for razor-sharp details. Panasonic’s sensor optimization achieves a solid ISO range from 100 to 51,200 native, expandable to a whopping 204,800 - ideal for low-light shooting. While a fairly standard resolution by today’s standards, its sensor size strikes a perfect balance of noise control, dynamic range, and reasonable file sizes for a wide range of use cases.

In contrast, the Pentax 645Z boasts a gigantic 51-megapixel medium-format sensor measuring 44 x 33 mm with a sensor area exceeding 1,452 mm² - roughly 70% larger than the Panasonic sensor. This expansive sensor real estate translates into exceptional image quality, stunning detail rendering, and extended dynamic range.

DxOMark scores attest to this, with Pentax 645Z achieving an outstanding overall score of 101, superior color depth at 26 stops, and an extraordinary dynamic range of 14.7 EV stops compared to typical full-frame sensors. Its low-light ISO rating of over 4500 reflects impressive noise performance despite the larger pixels required. Such characteristics make it an excellent tool for commercial, landscape, and fine art photographers who prioritize ultimate image fidelity over portability.

Pentax initially planted itself firmly in medium format territory to compete with Hasselblad and Phase One-type kits well beyond this price bracket. While its heft and file sizes may deter casual shooters, medium-format delivers results unattainable on smaller sensors.

Image Quality In Practice: Resolution, Dynamic Range, and High ISO Performance

I tested both cameras across various lighting conditions and subjects, always pushing each to extract their full potential.

The Panasonic S5’s 24 MP sensor may seem modest on paper but in practical scenarios, it nails glass-sharp rendering and excellent color reproduction. It lacks a low-pass filter, so fine details like hair strands, textured clothing, or foliage come through crisply. Its native ISO 100 lets you maximize dynamic range in bright daylight, but when the light fades indoors or on cloudy days, I appreciated how ISO 6400 to 12800 remained surprisingly clean with minimal artifacts.

The Pentax 645Z’s 51 MP files produced stunning detail on large prints and crop-heavy editing. Scenery shots showed nuanced tonal gradations and shadow recovery that made RAW editing a joy, thanks to that superlative dynamic range. The large sensor size helps it achieve a more three-dimensional look, with smoother transitions and richer colors.

However, high ISO sensitivity, while still impressive, shows some noise creeping in beyond ISO 3200. Thankfully, medium format sensors are rarely pushed to such extremes, given their role in controlled environments or slow shutter-speed landscape work.

Panasonic S5 front Panasonic S5 screen back Pentax 645Z front Pentax 645Z screen back

When reviewing my landscape shots on both cameras, the Pentax 645Z excelled in dynamic range and color depth, rendering sky gradients and leafy textures with subtlety unmatched by the Panasonic S5. Yet for travel or event photography where speed and light adaptability are crucial, the S5’s balance of resolution, noise performance, and speed shone.

Autofocus and Burst Shooting: Catching Fleeting Moments

Autofocus performance often separates a “nice camera” from a versatile tool - especially for wildlife, sports, or street shooting.

The Panasonic S5 uses a contrast-detection autofocus system with 225 focus points and face detection. It offers continuous autofocus, single AF, tracking, and touch AF on its live view screen. While not implementing phase-detection on sensor, the autofocus proved fast and accurate for most subjects. Eye-detection for portraits is present but not as refined as some competitors with more advanced AI.

In my hands, the S5 reliably tracked moving subjects, though the 7 fps continuous shooting speed felt borderline for fast action, notably compared to newer mirrorless models. However, it supports 4K and even 6K photo modes, letting you extract high-resolution stills from video bursts - a practical feature for wildlife and sports.

The Pentax 645Z’s autofocus uses phase detection with 27 cross-type points clustered more centrally. This results in snappy focus acquisition in good light, but the system is somewhat slower than modern mirrorless cameras and less forgiving with fast-moving or erratically moving subjects. Continuous shooting speed peaks at 3 fps, limiting its usability for high-speed action.

Still, the 645Z’s precise AF shines in portrait and landscape applications where accuracy outweighs speed, delivering consistent focus on static or slow-moving subjects.

Video Capabilities: A Modern Mirrorless Advantage vs Traditional Medium Format

For most professional photographers today, video is a critical consideration.

The Panasonic S5 is designed with hybrid shooter needs in mind. It records crisp 4K video at up to 60p in 10-bit 4:2:0 internally and 4:2:2 via HDMI, supporting H.264 and H.265 codecs. It also offers full support for microphone and headphone jacks, enabling professional audio workflow. The inclusion of in-body 5-axis sensor stabilization and a fully articulating touchscreen makes handheld 4K video surprisingly smooth and flexible.

I found the S5 an excellent B-camera for video work, small documentary projects, and hybrid photo-video shoots. Panasonic’s well-tuned video menus and waveform display cemented its status as a versatile choice for professionals working across media.

Alternatively, the Pentax 645Z is primarily a stills champion with limited video: full HD 1080p capped at 60i (interlaced). No 4K options are available, and no headphone jack limits audio monitoring. Video functionality is basic and best suited as a supplementary tool, not for serious videography.

Weather Sealing and Durability: Ready for the Elements?

When you head outdoors, your camera’s robustness can make or break the shoot.

Both cameras excel in weather sealing but with different extents:

• The Panasonic S5 features environmental sealing around doors and dials but lacks official dustproof or freezeproof ratings. It’s fine for rain and light dust, but I personally avoid extreme conditions without additional protection.

• The Pentax 645Z is a professional-grade beast in durability: dustproof, freezeproof to -10°C, and fully weather sealed. This level of protection is rare outside medium format DSLRs and makes it suited for rugged fieldwork, from alpine landscapes to desert expeditions.

Viewfinder and LCD Screen: Crafting the Photographer’s Visual Experience

For me, the quality and type of viewfinder and LCD viewing system heavily influence shooting comfort.

The Panasonic S5 sports a bright electronic viewfinder (EVF) with 2,360k dots resolution, 100% coverage, and 0.74x magnification. While EVFs historically lagged ocular precision, the S5’s EVF showed no perceptible lag and brilliant clarity even in dim light, with instant preview of exposure changes. Its 3.0-inch fully articulating touchscreen with 1,840k dots resolution allowed flexible angles for video and vlogging.

The Pentax 645Z has a traditional optical pentaprism viewfinder boasting 0.85x magnification and 98% coverage. The optical EVF offers an immersive experience with natural colors and no lag but lacks exposure preview - relying on experience and histogram checks. The 3.2-inch tilting LCD screen’s 1,037k dot resolution is bright but no touchscreen.

Lens Ecosystem and Compatibility: Unlocking Creative Potential

Lens availability dramatically shapes camera usage.

The Panasonic S5 uses the Leica L mount, compatible with Panasonic’s own Lumix S lineup, Sigma’s L-mount offerings, and Sigma’s increasingly broad lens range. Currently, there are about 31 native lenses covering wide apertures and focal lengths from ultra-wide to super-telephoto, suiting portraits, travel, macro, and wildlife alike.

The Pentax 645Z uses the Pentax 645AF2 mount, a niche medium format lens system with a total of only 6 native lenses available. These lenses are mainly high-performance primes covering essential focal lengths but fewer than modern mirrorless lineups.

For photographers seeking comprehensive versatility, Panasonic’s lens ecosystem will feel more generous and accessible. Medium format users often lean on a small set of ultra-high-quality primes for controlled compositions such as fine art and studio.

Battery Life and Storage Flexibility: Keeping the Workflow Moving

Battery reliability is crucial for long shoots.

The Panasonic S5 delivers around 440 shots per charge, reasonable for a mirrorless system but with some room for improvement. It supports USB charging and power bank operation - a boon for travel shooters needing lightweight power solutions. Dual SD card slots provide ample and flexible storage options, including backup or overflow modes.

The Pentax 645Z impresses with 650 shots per battery charge despite its large sensor and bright optical viewfinder, reflecting DSLR efficiency. Additionally, it has dual SD/SDHC/SDXC card slots for redundancy.

Users prioritizing extensive all-day shooting with minimal power concerns may favor the 645Z, but Panasonic’s charging flexibility balances this for mobile shooting.

Use Case Deep Dives: Which Camera Shines in Your Genre?

Portrait Photography: Skin Tones and Bokeh

The Pentax 645Z’s medium format sensor provides breathtaking tonal gradations and natural skin rendering unmatched by typical full-frame sensors. Combined with medium format primes offering smooth, creamy bokeh, it’s a dream for studio and fine art portraits where subtle tones and shallow depth-of-field impact are critical.

The Panasonic S5’s fast autofocus with face detection strikes a nice balance for environmental portraits, capturing good bokeh with Leica-compatible fast lenses. Its articulating screen also aids in engaging with subjects creatively.

Landscape and Fine Art

No contest here: the Pentax 645Z is king for landscape photography. Its outstanding dynamic range, high resolution, freezeproof build, and ultra-wide-angle medium format lenses deliver unrivaled image quality. Ideal for large prints and detail-critical projects.

The Panasonic S5 is capable for landscape work, especially when portability and rapid handheld shooting matter. Its sensor’s dynamic range is solid but doesn’t reach medium format standards.

Wildlife and Sports Photography

The Panasonic S5’s lighter body, faster continuous shooting (7 fps vs 3 fps on 645Z), and superior autofocus tracking favor it clearly for wildlife or sports. Although not the fastest mirrorless on the market, it outpaces the 645Z’s slower, less sensitive AF and frame rate by far.

Pentax’s camera is seldom chosen for action sports due to these speed constraints and heavier body.

Street Photography and Travel

Compact size, lighter weight, articulation, and quiet operation give the Panasonic S5 a clear edge for street shooting. Its excellent high ISO performance and discrete shutter modes allow for telling moments in varying light.

While the 645Z could be used for travel - it’s an absolute tank that demands commitment and large bags, so it’s usually reserved for targeted shoots instead.

Macro Photography

Panasonic’s lens ecosystem includes macro lenses that leverage in-body stabilization to create tack-sharp close-ups handheld. Medium format’s depth of field characteristics require stopping down, making it less suited for shallow portrait-style macro.

Professional Workflows and Reliability

Both cameras deliver dual card slots, extensive bracketing modes, and tethering support (via USB 3 for 645Z and USB-C for Panasonic), key for professionals managing backups and workflows. File compatibility is full raw support in both.

However, the Pentax 645Z holds a niche as a medium format professional tool with unparalleled color depth and large TIFF-sized files common in advertising and fine art.

Weighing the Value: Comparing Price to Capability

At approximately $2000 body-only, the Panasonic S5 offers a fantastic value for full-frame hybrid shooters craving 4K video, solid stills, and rangefinder portability.

The Pentax 645Z costs over $5000, reflecting the costs inherent to medium format technology and build quality but without modern video features. It’s a serious investment for image quality above all.

How Each Camera Ranks by Photography Genre

Final Thoughts: Which Camera Fits You Best?

Over my years testing thousands of cameras, I’ve learned there’s no one-size-fits-all device, especially between a full-frame hybrid and a medium format DSLR like these.

Choose the Panasonic Lumix S5 if you:

• Require a lightweight, portable camera for travel, street, wildlife, and video
• Want 4K video with professional audio options
• Need a modern electronic viewfinder and touchscreen interface
• Desire robust autofocus with face detection and burst shooting
• Are budget-conscious but want a solid all-rounder

Opt for the Pentax 645Z if you:

• Prioritize absolute image quality with medium format resolution and dynamic range
• Work mostly in controlled conditions like studio, landscape, and fine art
• Need a rugged, weather-sealed camera for extreme environments
• Can handle slower autofocus and shooting speeds
• Have a larger budget for top-tier stills but not video focus

My Personal Recommendation

For a versatile pro or serious enthusiast who photographs a broad range of subjects, the Panasonic S5’s hybrid approach and portability deliver more bang-for-buck and creative freedom. However, if ultimate detail, tonal nuance, and medium format excellence are your paramount goals - especially in landscapes or portraits - the Pentax 645Z remains a stellar classic that rewards patient, deliberate shooting.

Both cameras have proven reliable in my extended shooting sessions, but the choice boils down to your style, subjects, and workflow needs. I’m always open to questions or sharing more shooting tips based on your unique photography journey.

Happy shooting!

Disclosure: I have no financial affiliation with Panasonic or Pentax. All opinions stem from extensive hands-on testing over years of professional use. My review process includes lab measurements, field shooting tests across lighting conditions, and comparisons against industry standards to ensure objective insights.