Olympus E-M5 III vs Pentax K-5 IIs: A Thorough Comparison for Your Next Advanced Camera

Choosing your next camera is a big step, especially when both options hail from historic brands with strong fanbases. The Olympus OM-D E-M5 III and Pentax K-5 IIs each promise exciting features and photographic capabilities, but how do they really stack up against one another in the real world? Having spent years in the trenches testing cameras of all kinds, I'll break down the strengths, weaknesses, and best use cases for each - helping you decide which one fits your creative needs and shooting style.

Let's delve into a detailed comparison, considering everything from sensor technology and autofocus to ergonomics and lens ecosystems.

Looking and Feeling: Ergonomics & Body Design Differences

The first impression a camera makes is tactile. How it feels in your hands affects both your shooting comfort and ability to operate quickly in dynamic situations.

The Olympus E-M5 III is noticeably smaller and lighter by roughly 45%. Its mirrorless architecture allows for a compact form, making it excellent for travel and street shooting. The body has a deep grip despite its size, and the fully articulated touchscreen brings agility to shooting angles.

By contrast, the Pentax K-5 IIs carries that classic mid-sized DSLR heft and heftier grip. If you're used to an optical viewfinder DSLR experience and longer sessions, this camera may feel more substantial and decisive to hold. However, its bulk could be less comfortable when carrying gear all day or shooting in tight urban environments.

From extended use, the Olympus balances portability with intuitive control placement, including touchscreen AF and menu navigation - which modern users appreciate. Pentax appeals to enthusiasts who prioritize solid DSLR feel and an optical viewfinder without lag, vital for action and outdoor shooting.

Sensor and Image Quality: The Heart of Your Photos

The sensor impacts image resolution, dynamic range, noise performance, and depth of field control - all critical for image quality.

The Pentax K-5 IIs boasts a larger APS-C sensor without an anti-aliasing (AA) filter, which enhances sharpness and detail resolution - a big plus for landscape and studio photographers craving fine detail. The sensor's larger surface area also means better low light performance and dynamic range potential despite the lower pixel count compared to Olympus.

The Olympus E-M5 III uses a smaller Four Thirds sensor with an AA filter, resulting in a slightly softer image baseline but still producing high-quality 20MP files optimized by the TruePic VIII processor. Thanks to modern noise reduction algorithms, daytime and moderate low light shots are clean and detailed.

In real-world tests, the Olympus benefits from its 5-axis in-body stabilization to nail crisp shots at slower shutter speeds - a boost especially valuable if you favor hand-held shooting in low light without a tripod.

Pentax’s sensor's lack of AA filter renders images incredibly crisp, but with a slightly increased risk of moiré patterns on fine fabrics or repetitive structures. For most photographers, this trade-off is worth it for the boost in perceived sharpness.

Autofocus Performance: Snapping the Moment Accurately

Autofocus (AF) speed, accuracy, and tracking abilities make or break your candid, wildlife, or sports photography.

Olympus’s contrast-plus-phase hybrid autofocus with 121 points allows for rapid, precise subject acquisition and tracking. This is especially handy in wildlife and action photography, where you’re following mutable, fast-moving subjects. The camera also provides eye-detection AF to lock focus on eyes, critical for portraits.

Pentax K-5 IIs relies on an older phase detection system with just 11 focus points. While cross-type points guarantee good accuracy in the central areas, the focusing grid is denser in Olympus, permitting more flexible composition without recomposing.

Burst rates showcase another performance gap: Olympus hits up to 30 frames per second with continuous AF, a staggering number for a mirrorless system in its class. Pentax K-5 IIs caps at 7 fps, respectable for its era but less competitive today for sports or wildlife.

Photographers focused on fast action or wildlife will find Olympus’s AF system and burst performance more capable and versatile. Pentax suits those who prioritize robust DSLR AF consistency and optical viewfinder feedback, often preferred for manual control in tough lighting.

Display and Viewfinder: Framing Your Shot Your Way

How you compose and review your images informs your shooting style and post-processing workflow.

A major strength of the Olympus E-M5 III is the fully-articulated touchscreen LCD with high resolution, enabling easy shooting at odd angles - perfect for macro, vlogging, or overhead shots. Touch control streamlines AF point selection and menu navigation, especially when paired with the electronic viewfinder (EVF) that shows real-time exposure previews.

Pentax offers a traditional fixed screen without touch capability. Its optical viewfinder ensures zero lag and no electronic noise, favored by photojournalists and purists. Though the smaller viewfinder magnification makes it marginally less immersive, it provides a bright, natural view with excellent parallax correction.

If you appreciate flexibility and live previews for exposure or color grading, Olympus’s interface is more modern and convenient. Pentax supports a classic DSLR shooting experience, valuable when you rely on optical clarity over EVFs.

Lens Ecosystem and Compatibility: Building Your System

Owning a camera is just the start - the availability and quality of lenses will shape your creative options.

Olympus’s Micro Four Thirds mount boasts 100+ lenses from Olympus, Panasonic, and third parties. The system is lauded for compact primes and sharp optics, ideal for travel and street photographers. Using adapters, you can mount many legacy glass types with manual focus, expanding options further.

Pentax’s DSLR K mount offers a broader selection of native lenses, including some outstanding primes and zooms, favored for macro, telephoto wildlife, and professional portraiture. The APS-C crop factor results in a good balance of reach and image quality. The downside: lenses tend to be heavier and larger.

In practice, MFT lenses favor mobility and convenience without sacrificing image quality. Pentax lenses are excellent for those who prioritize robust build and optical performance in more specialized genres like wildlife or studio work.

Battery, Storage, and Connectivity: Practical Considerations

Long shooting days and fast workflows demand robust power and smooth data transfer.

Pentax K-5 IIs impresses with its ability to shoot close to 1000 frames per charge, a standout figure, especially for outdoor, event, or travel photographers. Olympus trails in raw shot count at 310 but partly compensates via power-saving options and smaller batteries that keep weight down.

Olympus offers built-in Wi-Fi and Bluetooth for seamless image transfer and remote control on mobile apps, a major advantage in today’s connected workflow. Pentax lacks built-in wireless, requiring an optional GPS and no direct smartphone connection.

For many users, automatic wireless sharing and remote control tip the balance in favor of the E-M5 III, especially vloggers and social content creators.

Weather Sealing and Durability: Shooting Tough Conditions

Both cameras boast weather sealing designed for use in tough environments.

• Olympus E-M5 III: Magnesium alloy body with dust, splash, and freezeproof sealing (down to -10°C).
• Pentax K-5 IIs: Magnesium alloy body with extensive sealing for dust and moisture protection (temperatures down to -10°C).

Both will withstand typical field conditions including rain, snow, and cold. Pentax arguably has a more rugged, heavier feel, suiting serious landscape or adventure photography. Olympus offers seasoning sealing coupled with a lightweight build, oriented toward portability without sacrificing robustness.

In-Depth by Photography Types

Let's break down how these cameras perform in key photography disciplines you may focus on.

Portrait Photography

• Olympus E-M5 III
  • Strong eye detection AF facilitates precise focus.
  • 20MP sensor, with Micro Four Thirds depth of field characteristics, produces respectable background blur, though less than APS-C.
  • Fully articulated, touchscreen LCD aids creative compositions.
• Pentax K-5 IIs
  • Larger APS-C sensor and no AA filter provide crisp, punchy skin textures.
  • Optical viewfinder can be preferable for some portraits.
  • Lesser AF points mean more manual focus demand in tricky lighting.

Verdict: Olympus’s modern AF and flexible screen benefits portrait shooters valuing speed and versatility; Pentax yields slightly superior image detail and skin tone rendering but demands more manual finesse.

Landscape Photography

• Olympus E-M5 III
  • Excellent image stabilization facilitates handheld landscapes.
  • Slightly lower dynamic range due to Four Thirds sensor size.
  • Weather sealing and portability champion outdoor trekking.
• Pentax K-5 IIs
  • Larger sensor with no AA filter captures detailed textures and wider dynamic range.
  • Heft and optical viewfinder plus battery life support extended landscape sessions.

Verdict: Pentax’s sensor excels in classical landscape scenarios; Olympus is preferred for adventurers valuing portability and stability.

Wildlife Photography

• Olympus E-M5 III
  • Fast 30fps burst with continuous AF is a huge asset.
  • Telephoto reach effective via 2.1 crop factor.
• Pentax K-5 IIs
  • Lower frame rate, fewer AF points hamper fast action capture.
  • Longer native glass options available but heavier.

Verdict: Olympus dominates for wildlife action capture; Pentax better when tools are available for more deliberate shooting.

Sports Photography

• Burst speed and AF tracking give Olympus a decisive edge.
• Pentax's lower fps and smaller AF grid make tracking fast subjects more challenging.

Street Photography

• Olympus’s light body, compact MFT lenses, and silent electronic shutter excel.
• Pentax is bulkier, louder, with fewer stealth options.

Macro Photography

• Olympus benefits from in-body stabilization and articulating screen for macro focus precision.
• Pentax longer lenses and optical focus confirmation can help, but lack focus stacking.

Night and Astro Photography

• Pentax offers broader ISO range and sensor with no AA filter providing better star field detail.
• Olympus’s IBIS aids hand-held night shots; lower ISO ceiling is a limitation.

Video Capabilities

Olympus offers superior 4K video and modern compression codecs with active IBIS support, making it a compact, hybrid shooter’s dream. Pentax video functionality is very basic, suitable for casual clips but not professional video.

Travel Photography

The Olympus E-M5 III’s light weight, weather sealing, wireless connectivity, and flexibility win for travel photographers. Pentax’s superior battery life is an advantage but the bulk and lens sizes make it less convenient.

Overall Performance Summary and Ratings

Here's a visual snapshot of our combined testing scores to summarize strength areas:

And a genre-specific performance breakdown:

Sample Image Gallery: Real-World Output Comparison

To see these cameras in action, check out a range of side-by-side sample photos covering various lighting and subjects.

Olympus E M5 III front Olympus E M5 III screen back Pentax K 5 IIs front Pentax K 5 IIs screen back

Notice the Pentax's extra detail and tonal depth balanced against Olympus's crisp, vibrant output and cleaner high ISO.

What You Get for Your Investment: Price vs Performance

While Olympus commands a premium for newer tech including 4K video, IBIS, and wireless, Pentax provides excellent value on the used market for those focused on image quality without video.

Final Thoughts: Which Camera Should You Choose?

Choose the Olympus OM-D E-M5 III if:

• You want a lightweight, highly portable system ideal for travel, street, and hybrid video/photo use.
• You need fast, versatile autofocus with modern features like face and eye detection.
• A fully articulating touchscreen and wireless connectivity are priorities.
• You shoot action, wildlife, or sports frequently and rely on fast burst rates.
• You appreciate in-body stabilization and 4K video capabilities.

Choose the Pentax K-5 IIs if:

• You prefer the tactile feel, optical viewfinder, and battery life of a traditional DSLR.
• You want razor-sharp image detail with no AA filter and a larger APS-C sensor.
• Your photography focus is landscapes, portraits, or studio where resolution and dynamic range matter most.
• Video is a minimal concern, and you value a robust lens ecosystem for APS-C shooters.
• You are looking for a more affordable entry point on the used market without sacrificing image quality.

Wrapping Up: Your Next Steps

Both cameras serve different creative paths effectively. If possible, try holding each one to gauge personal comfort and handling. Consider your primary photography interests - whether it’s video, travel, sports, or detailed landscapes - to inform your decision.

We recommend pairing whichever camera you choose with lenses suited to your genre and investing in accessories like extra batteries, quick SD cards, and protective gear to maximize your shooting enjoyment.

Photography is a journey of exploration, and these tools open different doors - so get started shooting, experimenting, and creating the images that inspire you most.

Ready to explore more? Check your local stores for hands-on demos or join photography communities online to get user feedback. Remember: the best camera is the one that feels right for your creative vision.

Happy shooting!