Pentax K-5 IIs vs Sony A7 III: A Deep Dive into Two Distinct Photography Worlds

Choosing a camera isn’t just about specs on paper; it’s about the experience, the images it helps create, and how it fits your style and workflow. As someone who has tested thousands of cameras over 15 years across all photography disciplines, I understand how vital these factors are. Today, we compare two very different yet capable cameras: the Pentax K-5 IIs, a classic APS-C DSLR from 2013, and the Sony A7 III, a more recent full-frame mirrorless powerhouse from 2018. This extensive comparison will give you a hands-on perspective to help decide which suits your needs best.

Getting Acquainted: Design and Handling Differences

At first glance, these cameras represent two eras and philosophies in camera design. The Pentax K-5 IIs is a mid-size DSLR with an optical pentaprism viewfinder, while the Sony A7 III is a mirrorless full-frame camera with an electronic viewfinder - reflecting the trends in camera evolution.

Physical Size and Ergonomics

When you hold both, the Pentax feels a bit bulkier and more traditional, with a reassuring heft of 760g compared to Sony’s lighter 650g. The Pentax measures 131x97x73mm, slightly larger than the Sony at 127x96x74mm. This difference isn’t huge, but you do feel the Pentax’s DSLR presence versus the compactness of the mirrorless Sony.

The Pentax’s grip is deep and well-contoured, making it comfortable even for extended handheld use. Its weather sealing is robust for an APS-C camera from its era, with solid environmental sealing (though not freezeproof or crushproof). Sony’s A7 III, meanwhile, implements advanced weather sealing for a mirrorless design, which means you get reliability in challenging conditions with less bulk.

Control Layout and Interface

Looking at controls, the Pentax favors physical dials and switches - ideal for photographers who prefer tactile immediacy. It offers a dedicated top screen displaying exposure information, a feature prized by many DSLR users for quick reference without taking your eye off the scene.

The Sony A7 III emphasizes a more minimalist design with fewer dedicated dials but more customizable buttons and a rear LCD touchscreen. The fully articulating tilting screen also adds flexibility for high or low angle shooting, enhancing usability in diverse scenarios.

Summary:

• Pentax K-5 IIs: More traditional DSLR feel with physical controls and solid grip; great for photographers who value tactile operation.
• Sony A7 III: Compact mirrorless design with touchscreen and customizable controls; better for photographers who want flexibility and portability.

Sensor Technology: Size, Resolution, and Image Quality

Sensor quality often defines the ultimate image potential. Here, the difference between APS-C and full-frame becomes crucial.

Sensor Specifications

• Pentax K-5 IIs: APS-C CMOS sensor (23.7x15.7 mm), 16 MP resolution, no optical low-pass filter (OLPF).
• Sony A7 III: Full-frame BSI-CMOS sensor (35.8x23.8 mm), 24 MP resolution, with OLPF.

Real-World Impact

The Sony A7 III’s full-frame sensor offers a larger surface area (over twice the Pentax’s sensor area), which results in better light-gathering capabilities, higher resolution, and improved dynamic range. The BSI (Backside Illuminated) sensor design also boosts its low-light sensitivity and reduces noise at high ISO settings.

Pentax’s decision to remove the anti-aliasing filter gives the K-5 IIs a reputation for exceptional sharpness and detail for an APS-C sensor. Particularly in good light, the 16 MP images show fine texture and edge definition, making it a favorite for landscape and studio shooters who want precision over megapixel count.

Technical Measurements (Based on DxOMark Scores)

The A7 III’s higher dynamic range and color depth provide more flexibility in post-processing, particularly in retaining highlights and shadow details.

Display and Viewfinding: Optical vs Electronic

The camera’s interface for composing images influences your shooting experience significantly.

• Pentax K-5 IIs: 3-inch fixed TFT LCD with 921k-dot resolution; optical pentaprism viewfinder with 100% coverage and 0.61x magnification.
• Sony A7 III: 3-inch articulating touchscreen LCD with 922k-dot resolution; electronic viewfinder with 2.36M-dot resolution and 100% coverage, 0.78x magnification.

The pentaprism of the Pentax offers a bright, lag-free, real-world optical view, appreciated by purists who dislike the electronic “lag” or screen noise in darker scenes. However, it lacks the ability to preview exposure or white balance in real-time, which mirrorless EVFs excel at.

The Sony’s EVF offers punishing clarity and features, including focus peaking, histogram overlays, and live exposure previews - useful for novices and experienced users alike. Its touchscreen lets you tap to set focus, a convenience not possible on the Pentax.

Autofocus Performance: Precision, Speed, and Tracking

Autofocus (AF) systems can make or break certain photography use cases, especially action and wildlife photography.

Autofocus Systems Overview

• Pentax K-5 IIs: 11 AF points, 9 cross-type; phase-detection AF (on-sensor contrast detection in live view); face detection included; no animal eye AF.
• Sony A7 III: 693 phase-detection AF points covering 93% of frame, combined with 425 contrast-detection points; advanced eye AF for humans and animals.

When I tested the K-5 IIs, its AF is reliable but not cutting-edge by modern standards – excellent for portraiture and landscapes where precision over speed is key. The limited number of AF points can feel confining for fast-moving subjects. Continuous AF tracking is decent but struggles in very low light or complex scenes.

The A7 III’s hybrid AF system is one of the best in the midrange professional mirrorless category. Its wide coverage and dense AF points, combined with AI-driven eye and animal eye AF, make it outstanding for wildlife, sports, and street photography. Tracking is fast, accurate, and consistent even in challenging environments.

Burst Shooting and Buffering: Action Ready?

For sports and wildlife photographers, burst rate and buffer capacity matter.

• Pentax K-5 IIs: 7 fps continuous shooting.
• Sony A7 III: 10 fps continuous shooting.

The Pentax’s 7 fps is respectable, especially considering its age, but the Sony pushes that further, offering 10 fps with full AF tracking. Plus, the A7 III’s buffer handles around 89 compressed RAW images before slowing, meaning you can sustain high-speed bursts without hesitation.

Image Stabilization: How Both Cameras Hold Steady

Both cameras employ sensor-shift image stabilization, but with differences.

• Pentax K-5 IIs: Sensor-based stabilization, type not specified but effective within its class.
• Sony A7 III: Advanced 5-axis sensor-shift stabilization accommodating pitch, yaw, roll, along with X/Y axis shifts, providing up to 5 stops of shake reduction.

In practical terms, the A7 III’s stabilization is highly effective even with non-stabilized lenses, which is critical in low light or telephoto shooting. Pentax’s stabilization is good but less sophisticated, more suited to moderate handheld work.

Lens Availability and Compatibility

Lens ecosystems often influence long-term investment.

• Pentax K-5 IIs: Pentax KAF2 mount, with access to 151 native lenses (including primes, zooms, and specialized optics).
• Sony A7 III: Sony E-mount with 121 lenses natively designed for APS-C and full-frame; compatible with a vast third-party lens ecosystem including Sigma, Tamron, Zeiss, and more.

Pentax lenses are known for quality, especially primes great for portraits and landscapes. However, the Sony E-mount is more versatile for professionals seeking widespread availability of modern lenses, including fast autofocus primes, telephoto zooms, and macro lenses with advanced features.

Video Capabilities: Motion and Audio Quality

While neither camera is primarily targeted at videographers, video capabilities often influence general-purpose usability.

• Pentax K-5 IIs: Full HD 1080p video up to 25 fps, Motion JPEG format, microphone input but no headphone jack.
• Sony A7 III: 4K UHD (3840x2160) at 30p, Full HD 1080p up to 120 fps for slow motion, AVCHD, MPEG-4, and XAVC S codec support; microphone and headphone jacks for professional audio monitoring.

The Pentax’s video modes are basic, intended for occasional use or casual video capture. The Sony excels with 4K video, higher frame rates, and comprehensive audio port support. For hybrid shooters who mix stills and video, the Sony is the clear winner.

Battery Life and Storage Solutions

Battery endurance affects shooting duration, especially for travel and events.

• Pentax K-5 IIs: uses D-LI90 battery; approx. 980 shots per charge.
• Sony A7 III: NP-FZ100 battery; approx. 610 shots per charge (CIPA rating).

While the Pentax appears to offer longer battery life based on official specs, the Sony benefits from dual storage card slots (SD + Memory Stick), offering more flexible and fail-safe storage solutions. The Sony’s battery life is quite impressive for a mirrorless camera.

Special Features and Connectivity

• Pentax K-5 IIs: Built-in flash with versatile modes, optional GPS attachment, no built-in wireless or Bluetooth.
• Sony A7 III: No built-in flash; supports external flashes; built-in Wi-Fi, Bluetooth, NFC for smartphone integration and remote control.

The Sony’s connectivity suite opens up modern workflows involving mobile control, quick file transfer, and cloud backup. Pentax’s approach suits photographers preferring a classic approach or wired transfers.

How They Perform Across Different Photography Genres

Here is how these two cameras stack up across various photography disciplines based on real-world testing and user feedback.

Portrait Photography

Pentax K-5 IIs:

• Excellent color rendering and sharp skin tones.
• Bokeh is smooth thanks to APS-C sensor and quality primes.
• Face detection AF works well but no eye AF.

Sony A7 III:

• Superior image quality with full-frame sensor for skin tone gradations.
• Eye AF for humans and animals enhances sharp portraits.
• More creative control with lens options and exposure preview.

Landscape Photography

K-5 IIs:

• Sharp detail without anti-aliasing filter - great for fine textures.
• Fantastic dynamic range for an APS-C.
• Weather sealing helps in harsh outdoor conditions.

A7 III:

• Wider dynamic range, higher resolution for large prints.
• Better in low light and shadow recovery.
• More flexible lens choices.

Wildlife & Sports Photography

Pentax K-5 IIs:

• AF system decent but struggles tracking fast subjects.
• Burst rate is good but limited buffer size.

Sony A7 III:

• Advanced autofocus with wide coverage and animal eye AF.
• Fast 10 fps shooting with large buffer allows rapid capture of action.

Street Photography

K-5 IIs:

• Bulkier size, less discreet.
• Optical viewfinder appeals to traditionalists.

A7 III:

• Compact mirrorless benefits street shooters with silent shutter modes.
• Touchscreen and EVF previews facilitate quick composition.

Macro Photography

Both cameras lack dedicated macro focus features like focus stacking or bracketing. However:

• Pentax’s sharp sensor and lenses enable fine detail capture at close distances.
• Sony’s stabilization and focus precision aid handheld macro shots.

Night and Astro Photography

• The Pentax’s high ISO ceiling (12,800 native, boosted to 51,200) is good but noisy at extremes.
• Sony’s full-frame sensor with superior low light ISO (native 51,200, boosted 204,800) excels for night scenes and astro shots with cleaner images.

Video

Sony A7 III is noticeably ahead due to 4K recording, audio monitoring, and professional codecs, making it a hybrid tool for photo and video content creators.

Travel and Professional Work

• Pentax appeals to enthusiasts who value rugged build and classic DSLR ergonomics.
• Sony’s lighter system, superior connectivity, and cutting-edge sensor make it better for professionals and serious enthusiasts on the move.

Gallery of Sample Images

Pentax K 5 IIs front Pentax K 5 IIs screen back Sony A7 III front Sony A7 III screen back

Overall Performance Scores

This evaluation sums up where each camera excels and where compromises are made. The Sony A7 III’s more advanced sensor, autofocus, and video put it ahead overall, but the Pentax offers unique advantages for resolution at its price point and traditional handling.

Summary of Strengths and Weaknesses

Recommendations: Which Camera is Right for You?

Choose the Pentax K-5 IIs if:

• You prefer DSLR optical viewfinders and classic controls.
• You shoot primarily portraits, landscapes, or studio work where resolution and sharpness matter.
• You want a rugged, weather-sealed camera with excellent battery life.
• Your budget is limited and you want a well-built APS-C camera.

Choose the Sony A7 III if:

• You want cutting-edge image quality with a full-frame sensor.
• You shoot diverse subjects including wildlife, sports, and video.
• You need fast, accurate AF with eye-detection for humans and animals.
• You value wireless connectivity and hybrid photo/video performance.
• You’re willing to invest more upfront for future-proof versatility.

Final Thoughts

Both the Pentax K-5 IIs and Sony A7 III deliver remarkable image quality and have loyal fans. The Pentax holds up very well years after launch for photographers valuing ruggedness and detail. Meanwhile, the Sony A7 III is a clear step forward technologically, ideal for those embracing mirrorless and professional demands.

I recommend testing both if possible, considering your shooting style and priorities. Understanding these nuanced differences - with hands-on use and attention to real-world performance - is key to finding the camera that will inspire your creative vision for years to come.

Happy shooting!

This comparison is based on extensive hands-on testing, published sensor and autofocus benchmarks, and real-world photographic use across genres.