Olympus E-5 vs Pentax K-3 III: A Comprehensive Comparison Across a Decade of DSLR Evolution

In the realm of advanced DSLR cameras, Olympus and Pentax have long been stalwarts, offering enthusiasts and professionals meticulously crafted bodies built around unique philosophies. Today, we dive deep into a detailed comparison between two representatives from these brands spanning very different technological eras: the Olympus E-5, announced in early 2011, and the Pentax K-3 Mark III, introduced a decade later in 2021.

These cameras bookend significant shifts in DSLR technology and photographic expectations, making such a comparison both an insightful examination of how the market evolved and an evaluation of what each might offer today based on your shooting style and priorities. Over the next several thousand words, I’ll guide you through these cameras with a focus on practical usage, sensor performance, autofocus, ergonomics, and more - based on extensive personal testing of both models alongside thousands of other cameras.

Olympus E-5 (left) vs. Pentax K-3 III (right): Notice the compact yet sturdy build of Olympus with Micro Four Thirds, versus a slightly larger APS-C body in the Pentax.

Foundations of Design and Handling - Ergonomics That Shape Your Day Behind the Viewfinder

When I first placed the E-5 and K-3 III side-by-side, the difference in size was immediately apparent, but not in a way that clearly favored one or the other. The Olympus E-5, a mid-size SLR housing a Four Thirds sensor, weighs around 800 grams with dimensions 143 x 117 x 75 mm. Its chunkier grip and the fully articulated 3-inch LCD - a rare feature in DSLRs around 2011 - provide a comfortable feel for long shoots, especially portrait and macro work requiring flexibility of angles.

The Pentax K-3 III, slightly lighter at 820 grams yet smaller in footprint (135 x 104 x 74 mm), uses an APS-C sensor, naturally demanding a more substantial lens mount and therefore thicker lenses. Pentax maintained a robust, weather-sealed chassis with more modern ergonomics including improved grip texture and button placement. Its fixed 3.2-inch touchscreen LCD with 1620k-dot resolution enhances previewing and menu navigation.

Both models sit firmly in the “advanced DSLR” camp, striking a balance between professional robustness and ergonomic consideration. The Olympus’s fully articulated screen makes it a versatile tool for macro, video, and awkward-angle shooting, which the Pentax’s crisp, touch-enabled LCD somewhat lacks but compensates with an improved bright rear display and streamlined controls.

Button and dial placements reveal different philosophies: Olympus E-5’s classic DSLR layout with dedicated dials; Pentax K-3 III embraces more modern ergonomics with touchscreen support.

Sensor and Image Quality: A Tale of Resolution, Noise, and Dynamic Range

Delving into the heart of image creation, sensor technology often determines how far a camera stretches your creativity. Here, the Olympus E-5 uses a 12MP Four Thirds CMOS sensor, sized at 17.3 x 13 mm, with a sensor area of roughly 225 mm². In contrast, the Pentax K-3 III boasts a 26MP APS-C CMOS sensor measuring 23 x 15.5 mm, with an area of approximately 356.5 mm² - more than 50% larger in surface.

The Pentax’s sensor not only delivers higher resolution (6192 x 4128 pixels) but also boasts no anti-aliasing filter, which translates to crisper fine detail and sharpness in images. The E-5’s inclusion of a low-pass (anti-alias) filter reduces moiré but softens textures moderately.

Technologically, the E-5 debuted TruePic V+ image processing aimed at enhancing color fidelity and noise management, but by today’s standards, low-light ISO sensitivity tops at 6400 native, with some boost available. Pentax’s K-3 III pushes the ISO ceiling dramatically to 1,600,000 - an almost absurd upper limit that, while unlikely to be usable at max, speaks to the camera’s low-light optimization and improved sensor design.

Dynamic range tells another story: Olympus scores around 10.5 EVs on DXO’s scale, respectable for a decade ago in a Four Thirds sensor, while Pentax, though untested on DXO, historically edges higher in APS-C sensor dynamic range. This implies more detail retention in highlights and shadows, crucial for landscape and high-contrast shooting.

Relative size and resolution differences between Olympus Four Thirds sensor and Pentax APS-C sensor - critical to detail and noise performance.

Autofocus and Burst Performance - Where Speed Meets Accuracy

Autofocus remains a highlight for photographers shooting action, wildlife, or spontaneous street moments. The Olympus E-5 features a hybrid autofocus system with 11 focus points, all cross-type - respectable for its time, with phase-detection for speed and contrast-detection for accuracy in live view and video. However, tracking moving subjects was never its strong suit, with the system lacking continuous focus tracking and face/eye/animal eye detection features common in later models.

Pentax K-3 III, a full decade newer, features an advanced AF system boasting 101 focus points, with 25 cross-type sensors distributed widely across the frame, and full AF tracking including eye-detection. This vastly improves success rates in sports, wildlife, and even candid street photography.

Continuous shooting speed furthers this contrast. Olympus offers a moderate 5 fps burst suitable for general photography but limiting for fast-paced events. Pentax jumps to 12 fps, almost doubling throughput, assisted by a deep buffer and faster storage interfaces.

In real-world testing under variable light, I found Olympus’s focus to be reliable for portrait and studio photography but requiring manual override for tracking subjects. The Pentax’s focus performed admirably not only in daylight but under low-light challenges, combined with greater autofocus point coverage helping maintain sharp focus on erratic wildlife.

Build Quality and Weather Sealing: Ready for the Field?

Both cameras advertise environmental sealing designed to withstand challenging shooting conditions, though neither claims full waterproofing or shockproofing.

Olympus’s E-5 sealed body reflects its back-to-back claim as a rugged DSLR, and though some of the seals are nearly a decade old now, initial testing showed good dust and moisture resistance aided by durable magnesium alloy chassis. Pentax, long known for field-ready DSLRs, ups the ante with the K-3 III construction, also magnesium alloy reinforced with high sealing standards, arguably providing a slight edge in comprehensive weather resistance.

Given the continuous advancement in seal technology, Pentax’s recent chassis likely offers more reassuring protection during rain-soaked hikes or dusty wildlife ventures.

Display and User Interface - Touchscreen or Articulated?

The Olympus E-5 sports a 3.0-inch HyperCrystal fully articulated LCD screen with 920k-dot resolution. This screen’s articulation capability gives extreme flexibility for shooting from above or below while maintaining consistent color and visibility under sunlight. However, it lacks touchscreen capability, requiring physical buttons and dials to navigate menus and set focus points.

Pentax’s K-3 III has a 3.2-inch fixed LCD with a high 1620k-dot resolution and integrates a responsive touchscreen interface. This facilitates quicker menu and focus point adjustment and makes reviewing images more intuitive. The fixed nature is a slight limitation for creative angles, but the combination of size, resolution, and touch interaction meets most modern photographer demands well.

The optical viewfinders on both cameras cover 100% frame with pentaprism design, but Pentax offers higher magnification (0.7x vs 0.58x on Olympus), contributing to easier manual focus critical for macro and manual-lens shooters.

Olympus’s articulation versus Pentax’s touchscreen - differing approaches for live view framing and control.

Lens Ecosystem and Compatibility - The Cornerstone for Creativity

Olympus’s E-5 utilizes the Four Thirds mount, an older standard superseded for mirrorless by Micro Four Thirds lenses (note the E-5 is often mis-categorized). Despite restricting the E-5 to Four Thirds lenses, Olympus has a respected lineup of 45 native lenses offering a good variety of primes and zooms - an advantage for photographers invested in Olympus glass from that era.

Pentax K-3 III features the Pentax KAF2 mount, giving access to a broad range of 156 lenses including legacy primes, modern weather-sealed optics, and third-party options with excellent optics. The larger APS-C sensor benefits from lenses designed explicitly for this format, yielding sharper results and faster apertures in many cases. The Pentax lens ecosystem stands out as versatile and deep, supporting everything from ultra-wide landscape lenses to super-telephoto wildlife options.

If you’re tied into a lens system or particularly value lens choice, Pentax’s broader and more current ecosystem is an undeniable advantage.

Battery Life and Storage: Endurance and Efficiency

Battery life is crucial when shooting on travel or extended assignments. The Olympus E-5, powered by a BLM-5 battery pack, impresses with rated life of around 870 shots per charge - exemplary for an older DSLR, aided by efficient processing and smaller sensor.

Pentax’s D-LI90 battery supports approximately 800 shots per charge, slightly less but within competitive range given the higher resolution sensor and faster frame rate demands. Real-world usage confirmed both cameras deliver a full day’s shooting with moderate image review and flash usage.

On media storage, Olympus accepts both Compact Flash (CF type I/II) and SD cards across two slots, a boon for redundancy and flexibility. Pentax uses dual SD slots with UHS-II support in slot 1, providing faster write speeds benefiting burst shooting and 4K video.

Video Capabilities - Surprise or Status Quo?

Video is an area where these cameras part ways significantly. The Olympus E-5 offers HD video capped at 1280x720 at 30 fps in Motion JPEG format - a useful feature in 2011 but now largely obsolete. Video enthusiasts will find limited codec support, no 1080p or 4K, and no advanced video stabilization modes.

Pentax K-3 III is a marked upgrade, supporting 4K UHD at 30p and various Full HD options at higher frame rates (60p), encoded in H.264 with Linear PCM audio. Added inputs for microphone and headphones enable better audio monitoring, making the Pentax an appealing hybrid tool for photographers dabbling seriously in video.

While neither is a dedicated cinematic camera, the K-3 III meets contemporary standards in DSLR video workflows.

Specialized Photography: Portraits, Wildlife, and Beyond

Portraits: Olympus’s sensor size and TruePic V+ produce pleasing skin tones with smooth bokeh, aided by the sensor-shift stabilization. However, Pentax’s higher resolution and advanced autofocus with eye detection foster more detailed portraits with precision focus.

Landscape: Dynamic range and resolution of the Pentax K-3 III clearly dominate, capturing more tonal gradations and detail, while its robust weather sealing suits outdoor shoots better. Olympus remains capable but less flexible for expanded cropping or large prints.

Wildlife & Sports: Pentax’s superior autofocus tracking and 12 fps burst give it an edge in capturing fast-moving subjects. Olympus’s 5 fps with lesser tracking limits action capture.

Street & Travel: Olympus’s articulated screen and smaller Four Thirds lenses lend to a more compact kit - discreet and versatile for street or travel. The Pentax, though larger, offers better image quality and battery performance, suited for those prioritizing output over portability.

Macro: Olympus benefits from sensor-based stabilization and screen articulation, useful for low-angle macro shots, but Pentax outperforms in focusing precision and higher resolution detail capture.

Night & Astro: Pentax’s extraordinary ISO range and sensor characteristics make night shooting and astrophotography stronger pursuits than Olympus’s more limited capabilities.

Connectivity and Modern Conveniences

Pentax adds built-in wireless connectivity and Bluetooth, streamlining file transfers and remote control via smartphone apps. Olympus E-5, by contrast, lacks any wireless features, limiting immediate sharing and tethering convenience.

Both offer USB and HDMI ports, but Pentax’s USB 3.2 ensures a faster tethering experience, while Olympus sticks to legacy USB 2.0 speeds.

Pricing and Value Perspective

At launch, Olympus E-5 retailed around $1700, and today can be found at used or refurbished prices far lower, representing a budget-friendly entry into DSLR photography with some legacy perks (optical viewfinder, articulating screen, solid lens selection).

Pentax K-3 III starts closer to $2000, reflecting current-generation technology, superior imaging specs, and more advanced video and autofocus systems. For photographers wanting the latest refinements and lens options, it justifies the premium.

Olympus E 5 front Olympus E 5 screen back Pentax K 3 III front Pentax K 3 III screen back

Summing Up Performance Scores and Genre Strengths

These scorecards capture the essence: Pentax K-3 III excels broadly with top marks in dynamic range, resolution, autofocus speed, and video; Olympus E-5 holds its own in ergonomics, battery life, and macro flexibility but lacks modern speed and pixel count.

Final Thoughts: Which Camera Is Right for You?

Choosing between the Olympus E-5 and Pentax K-3 III boils down to specific needs and budgets:

• Choose Olympus E-5 if:
  You desire a rugged DSLR with versatile articulating screen, excellent battery life, and access to a solid Four Thirds lens kit at a bargain price. Ideal for macro, portrait, or travel enthusiasts valuing handling and legacy lens access over resolution or burst speed.

• Choose Pentax K-3 III if:
  You require cutting-edge APS-C sensor performance, fast and accurate autofocus for wildlife or sports, 4K video capabilities, and an extensive modern lens ecosystem. Great for professionals or serious amateurs wanting superior image quality and versatility across genres.

In the end, while the Olympus E-5 remains a “good boy” for solid traditional DSLR uses, the Pentax K-3 Mark III is undeniably the more powerful and future-proof tool for today’s demanding shooters.

If you want to drill further into any of these categories or see sample files, I’ve extensively tested both bodies in field conditions - happy to help guide your next photographic step. After all, picking the right camera is about matching tool attributes to your vision behind the lens.