Pentax K-5 vs Sony A9: A Deep Dive into Two Cameras from Different Worlds

Choosing a camera can feel like standing at a fork in the road with two wildly different paths stretching ahead. On one side, you have the Pentax K-5, a stalwart mid-size DSLR with roots going back to 2010 - a classic for enthusiasts who cherish rugged build, solid ergonomics, and traditional shooting pleasure. On the other, the Sony A9 stands like a futuristic beast from 2017 - a mirrorless powerhouse built for blazing speed, cutting-edge autofocus, and pro-caliber video prowess.

I've spent years in the thick of camera tests, peering into specs, pushing buttons, and synthesizing what really matters when the camera stops clicking and the photographer takes over. So buckle up as we explore head-to-head what these two represent today, peeling back beyond spec sheets to see how they fare across all major photography genres, technical metrics, and real-world use.

First Impressions: Feel, Form, and Handling

Right out of the gate, you notice the physical gulf between the K-5 and the A9. The Pentax K-5 is predictably DSLR-esque, with a sturdy, almost reassuring heft of 740 grams and dimensions that affirm traditional mid-size SLR ideals: 131 x 97 x 73 mm. It carries that classic pentaprism hump, an optical viewfinder, and a fixed 3” TFT LCD - functional and durable but with a design ethos from a decade ago.

The Sony A9, at 673 grams and more compact (127 x 96 x 63 mm), encapsulates the mirrorless aesthetic: smoother lines, a smaller stature, and a tilting touchscreen with crisper resolution. Not a massive difference on paper, but in hand, the difference is palpable. The A9 fits more snugly for smaller hands, and its interface benefits greatly from a modern touch UI.

Pentax keeps the traditional DSLR control layout, which is great if muscle memory is your thing - but I found myself occasionally fumbling slightly in live view or video mode. The Sony A9’s top controls are more streamlined, with customizable buttons and a clever rear dial setup that facilitates rapid exposure adjustments.

If you value classic ergonomics and a solid grip paired with sturdy build - plus weather sealing baked into the body - the K-5 still delivers. Meanwhile, the A9 edges ahead with a more future-facing design philosophy that's also built tough and offers excellent weather sealing.

Inside the Frame: Sensor Size, Technology, and Image Quality

Here's where the story takes a dramatic turn. Pentax K-5 features a 16MP APS-C CMOS sensor (23.7x15.7mm), with an anti-aliasing filter and Prime II processor - the same format beloved by many enthusiast-level DSLRs in the early 2010s. Decent resolution, respectable dynamic range, and respectable ISO capabilities up to 12,800.

Sony A9, in contrast, packs a 24MP full-frame BSI-CMOS sensor (35.6x23.8mm) and the highly regarded BIONZ X processor. In 2017, this was cutting-edge tech - not just full-frame, but back-illuminated sensor architecture, yielding impressive low-light prowess and overall image fidelity.

To put numbers on it: DxO’s test scores rate the K-5’s sensor at 82, with color depth of 23.7 bits and dynamic range of 14.1 EV stops. The A9 scores 92 overall, with a color depth at 24.9 bits, and a dynamic range of 13.3 EV (slightly less but still excellent). Where the A9 truly shines is in low-light ISO performance - a whopping 3,517 ISO rating versus K-5’s 1,162. This is the difference between noisy images at night and clean, usable shots at moonlight levels.

Real-world test shots bear this out: the K-5 holds vivid colors and has commendable shadow detail for its era, but in dim conditions and higher ISO settings, grain becomes disruptive. The A9’s larger sensor and efficient noise reduction keep images crisp even at 12,800 ISO and beyond.

Views Through the Finder and Back Screen

One of my key criteria when testing cameras hands-on is how well they communicate information optically and on the rear panel. Pentax’s K-5 uses a bright, 100% coverage optical pentaprism with a magnification of 0.61x. While no electronic overlays or focus peaking help you here, the clarity and immediate feedback of an OVF is timeless.

Sony’s A9 tosses in a high-res electronic viewfinder (EVF) at 3,686k dots, covering 100% and boasting 0.78x magnification. The EVF offers a WYSIWYG preview with instant exposure simulation, focus peaking, and face/eye detection overlays, which can be invaluable under challenging conditions.

The rear LCD on the K-5 is fixed with a 921k-dot resolution - sharp for its time but non-touch and limited in flexibility. The A9 sports a tilting, touch-enabled 3” screen with 1,440k dots for vibrancy and easier composition from awkward angles.

While purists might swear by the optical finder for real-time clarity, I found the A9’s EVF a revelation when tracking moving subjects or reviewing images in tricky lighting. The touchscreen also accelerates workflow, particularly when using focus points or swapping settings on the fly.

Autofocus: The Tale of 11 Points Versus 693

Autofocus is where Pentax’s K-5 feels genuinely nostalgic - it offers an 11-point system with 9 cross-type sensors, combining both phase-detection and contrast-detection AF methods. It’s decent for focused still subjects and can track modest movement.

Enter the Sony A9, which utterly obliterates this with 693 phase-detection AF points spread across almost the entire frame (with unknown cross-type specifics, though all are impressively responsive). It incorporates sophisticated subject tracking, real-time eye and animal eye detection, and continuous AF performance at up to 20fps with no blackout.

This difference isn’t just marketing hyperbole. In my wildlife and sports testing, the K-5 occasionally hunted focus and lost track of unpredictable action, while the A9’s AF was a laser-guided missile - consistent, blazing fast, and reliable for even erratic subjects.

Speed and Burst Shooting: Rabbit Versus the Cheetah

If you shoot sports, wildlife, or other action-packed scenes, frame rates can make or break the shot.

Pentax K-5’s continuous shooting tops out at 7 FPS, respectable for its era. However, the buffer fills reasonably quickly if shooting RAW, and the optical viewfinder blacks out briefly between shots.

Sony A9 confidently smashes ahead with a crazy-fast 20 FPS shooting rate, no blackout in viewfinder thanks to its electronic shutter, and a huge buffer for sustained burst capture. Add to that a max electronic shutter speed of 1/32000s and silent shooting, which really opens creative possibilities, from shooting wildlife undisturbed to quiet events.

Build Quality and Durability: Tried-and-True versus Modern Durability

Both cameras tout environmental sealing to protect against dust and moisture, a necessity when you shoot outdoors often. Pentax has always been known for rugged DSLRs, and the K-5 certainly feels bulletproof with a magnesium alloy body and weather sealing. It’ll slap around with you.

Sony’s A9, while mirrorless and slightly smaller, does not skimp on sealing. Its body is similarly robust for professional use, designed to handle rough conditions without hesitation.

Battery Life and Storage: Marathons Versus Sprints

Ever been on a day-long shoot only to find the battery gasping? Pentax K-5 excels here with a remarkable 980 shot rating per battery charge, outpacing many modern mirrorless cameras. For travel photographers and event shooters, this means fewer battery swaps.

Sony A9, packing more technology, falls back to about 650 shots on a single charge - not shabby for a mirrorless but requires a strategy of spare batteries on longer shoots.

Storage-wise, the K-5 uses a single SD/SDHC/SDXC card slot, whereas the A9 upgrades with dual SD slots supporting UHS-II, a must-have for pros who want instant backups and faster write speeds.

Lens Ecosystem: The Legacy versus The Modern

Pentax's K-mount lens ecosystem extends back decades. This means the K-5 can mount 151 lenses, from vintage primes to modern glass, offering broad creative flexibility and excellent value for budget watchers.

Sony E-mount lenses number over 120 and are growing fast, thanks to Sony and third parties targeting mirrorless with autofocus and optically advanced designs. The modern design of E-mount lenses tends to be more compact and often incorporates sophisticated image stabilization.

Connectivity and Extras: Old School Versus Wired for the Future

Sony’s A9 boasts built-in Wi-Fi, Bluetooth, and NFC for smooth file transfer and remote control - features photographers increasingly take for granted. Pentax K-5 offers no built-in wireless, relying on optional GPS.

Video-wise, K-5 shoots Full HD 1080p at 25fps max with Motion JPEG format - a bit rudimentary for today’s standards but adequate for casual usage. A9 supports 4K video (3840x2160) with versatile formats like MPEG-4, AVCHD, and H.264, headphone jacks for professional audio monitoring, and in-body 5-axis stabilization - catering to hybrid shooters and videographers.

How They Perform Across Photography Genres

Let’s break down what these cameras bring to the party by genre:

• Portraits: K-5’s 11-point AF and pleasant color rendering produce flattering skin tones, but the A9’s eye and animal eye AF combined with full-frame bokeh and superior dynamic range deliver a significantly more professional final image.

• Landscape: Both weather-sealed and robust, but the A9’s higher resolution and cleaner high-ISO images shine in dynamic range challenges like dawn/dusk; K-5 offers outstanding value here.

• Wildlife: The K-5 can keep up with modest bursts, but A9’s 20 FPS with zero blackout and sophisticated AF make it a clear winner.

• Sports: Sony A9 is built for speed and tracking; K-5 trails as a capable but less precise alternative.

• Street: The K-5 feels bulky and less discreet; the A9, being mirrorless and quieter, feels more agile and flexible for candid shooting.

• Macro: Both camera bodies perform similarly, though the K-5’s sensor stabilization can help, balanced by A9’s superior autofocus precision.

• Night/Astro: The A9’s low-light performance and high-ISO capabilities dominate here.

• Video: A9 is the uncontested leader with 4K, audio ports, and stabilization.

• Travel: Carrying weight vs battery life is a tradeoff; K-5’s longer battery and ruggedness make it a dirt-road traveler’s friend, while A9’s compactness and speed suit fast city-hopping.

• Professional Work: A9’s dual slots, file type versatility, and connectivity make it ideal for demanding workflows; K-5 feels more amateur-enthusiast.

Pentax K 5 front Pentax K 5 screen back Sony A9 front Sony A9 screen back

Ratings Recap: The Scoreboard Doesn’t Lie

Bringing it all together numerically can help, but remember, numbers never tell the full story.

The A9 scores 92 on DxOmark, shining on overall performance, while the K-5 stands at 82, respectable for its generation. When drilling down:

• Speed and autofocus: A9 leads decisively
• Image quality under demanding conditions: A9 ahead
• Battery endurance: K-5 wins comfortably
• Build quality: Both strong contenders
• Video and connectivity: A9 dominant
• Value per dollar: K-5 gives incredible bang for a budget around $800, versus A9’s $4,498 pro-level pricing

Final Thoughts: Who Should Buy Which?

The Pentax K-5 is a beautiful relic that still serves as a highly capable tool, especially for enthusiasts who appreciate rugged construction, traditional DSLR experience, and excellent value for the money. It's great for hobbyists working in standard conditions - portraits, landscapes, and casual wildlife - with patience for its autofocus quirks and modest video.

The Sony A9, meanwhile, breaks the mold toward the future of photography: a mirrorless titan adept for advanced amateurs and professionals craving unparalleled speed, highly accurate AF, sensational low-light shooting, and pro video capabilities. It’s a fantastic choice if you shoot fast action, demand high image quality, and want a versatile hybrid tool.

So, do you want the dependable DSLR companion that feels like an old friend - solid, reliable, and affordable? Or the cutting-edge mirrorless marvel built for the professional battlefield? Either way, both cameras hold their unique charm and prove that no single camera rules every realm.

If you enjoyed this detailed breakdown or have specific questions about your shooting style, drop a comment - after all, choosing a camera is as personal as picking the right lens. Happy shooting!