Olympus OM System OM-5 vs Sony Alpha A9: A Tale of Two Mirrorless Warriors

In the ever-evolving arena of mirrorless cameras, choosing the right tool can feel like picking a favorite child - if one child excelled in marathon running and the other in chess. On one hand, we have the Olympus OM System OM-5, a compact, rugged Micro Four Thirds marvel designed with versatility in mind. On the other, the Sony Alpha A9, a full-frame powerhouse built with pro speed and precision at its core.

I've had the privilege - and occasional frustration - of testing thousands of cameras across genres, so today, let's embark on a deep dive into these two quite different beasts. Are you a pro who needs blistering speed and image quality? Or a travel enthusiast craving portability without sacrificing performance? We’ll cover everything, from tech specs through real-world field tests, to find out which one answers your photographic prayers. Buckle up.

First Impressions: Size, Ergonomics, and Handling

When I first held the two cameras side-by-side, it was like comparing a nimble ninja to a heavyweight boxer.

The OM System OM-5 (414g, 125x85x50mm) is delightfully compact - nearly half the weight of the A9 - and fits comfortably in one hand. Its SLR-style mirrorless body feels rugged and thoughtfully designed for long treks, especially with its extensive weather sealing. The fully articulated 3-inch touchscreen and the modest top-plate keep its footprint trim.

Meanwhile, the Sony A9 (673g, 127x96x63mm) is noticeably larger and thicker, its beefier grip feeling reassuringly solid for telephoto lenses or extended shoots. The A9’s tilting 3-inch touchscreen is higher resolution, and the sturdy build screams “professional studio and field use.” Ergonomically, it boasts more physical controls, beneficial for intuitive adjustments on the fly.

While Olympus prefers a simpler dial setup with custom buttons that can feel cramped to larger hands, Sony delivers a generous array of buttons and two multi-directional dials that make manual tweaks faster - no fumbling through menus during a football game.

Verdict: For travelers or anyone prioritizing portability, the OM-5's smaller, weather-sealed body wins points. For ergonomic mastery under pressure, the A9's control layout and larger grip prevail.

Sensor Technology and Image Quality: Who Sees Best?

Size matters - especially when it comes to sensors.

The OM-5 sports a 20MP Micro Four Thirds sensor (17.4x13 mm), which is physically smaller than the Sony A9’s full-frame 24MP BSI-CMOS (35.6x23.8 mm). The sensor area difference is significant: roughly 226 mm² vs 847 mm², meaning the Sony collects almost four times more light.

What does this translate to practically? In well-lit conditions, both deliver crisp images with excellent color. Olympus’s sensor incorporates a low-pass (anti-aliasing) filter, slightly softening fine detail to quell moiré - a sensible choice for fieldwork. Sony's A9 uses a backside-illuminated design, delivering superior noise control, dynamic range (13.3 stops vs estimated lower for OM-5), and color depth (DxOMark reports 24.9 bits for A9).

When shooting at high ISO (above 3200), the A9's sensor excels, pushing clarity where the OM-5’s smaller sensor begins to show noise and detail loss. However, Olympus’s new processing algorithms and TruePic IX engine (although not officially stated but inferred from lineage) keep noise well-managed for a Micro Four Thirds sensor.

Sharpness and resolution also weigh in Sony’s favor, with the A9 delivering images sized up to 6000x4000 pixels vs OM-5's 5184x3888 - extra pixels to crop or print large without quality loss.

Bottom line: If image quality is king, particularly for large prints, night shots, or cropping-heavy work, the A9’s sensor is a clear winner. OM-5 offers impressive quality for its class but can’t sidestep the physical limits of Micro Four Thirds.

LCD & Electronic Viewfinder: The Window to Your Art

The interface is your visual playground, so how these two cameras deliver matters.

Olympus’s fully articulated 3-inch LCD with 1.04 million dots allows easy framing from wild angles - including selfies, thanks to its front flip. The touchscreen is responsive, though arguably modest compared to Sony’s more refined display. The OM-5’s electronic viewfinder (EVF) sports a resolution of 2.36 million dots with 0.68x magnification, offering a bright and lag-free preview but sometimes showing slight pixelation in low light.

Sony’s A9 has the edge with a higher-res EVF at 3.69 million dots and 0.78x magnification - sharp, bright, and with excellent refresh rates that excel at fast action tracking. The 3-inch tilting touchscreen (1.44 million dots) supports touch focusing and intuitive menu navigation, although it’s not fully articulated like Olympus’s.

For photographers who rely on eye-level composition and precision manual focusing, Sony’s EVF feels less fatiguing and more immersive over long sessions.

Summary: The OM-5’s articulated screen wins versatility points, useful for vlogging and macro work. The A9’s superior EVF quality makes it better for critical focus and fast-paced shooting. It’s a tradeoff between flexibility and clarity.

Autofocus and Speed: Catching the Decisive Moment

If you shoot sports, wildlife, or spontaneous street moments, autofocus performance can make or break your day.

The OM System OM-5 uses a hybrid AF system with 121 focus points employing both contrast and phase detection. Face detection is solid, and continuous AF tracking keeps up decently for casual subjects. However, it lacks animal eye-detection, which is a slight oversight for wildlife photographers hunting elusive critters.

In burst mode, the OM-5 shoots at a respectable 10 fps mechanical shutter, extending to 30 fps with electronic shutter - but at reduced buffer depth. This setup works well for travel, street, and light sports photography but may struggle with prolonged fast action.

Now for the big gun: the Sony A9 features an advanced 693-point hybrid AF system with on-sensor phase detection covering 93% of the frame. It supports eye AF for humans and animals - a godsend in portrait and wildlife genres - and delivers unmatched tracking accuracy with predictive algorithms and deep learning.

The A9’s burst rate hits 20 fps with an electronic shutter, dead silent, and with near-zero blackout - a feature that genuinely helped me nail fast tennis rallies and bird flights. The buffer allows for hundreds of continuous JPEG+RAW frames, a boon when the defining moment comes in three seconds or less.

Quick takeaway: The A9 is the autofocus Ferrari; rapid, precise, and relentless. The OM-5, however, is an all-around performer with more modest speed, ideal for enthusiasts capturing everyday moments.

Build Quality and Weather Sealing: Ready for Adventure?

Neither camera is a delicate flower.

Olympus’s OM-5 continues the brand’s legacy of robust weather sealing, resistant to dust, splashes, and freezing temperatures (down to -10°C). Its magnesium alloy chassis shrugs off rough handling, letting you concentrate on composition, not coddling.

Sony’s A9 is similarly well-sealed, sturdy, and built for the rigors of daily professional use. Both cameras eschew claims of full waterproof or shockproof status - nothing here is an underwater camera - but their sealing ratings mean they’ll take a beating outdoors without complaint.

Still, the OM-5’s smaller size and lighter weight make it more comfortable for extended hikes - where less weight means more pictures.

Lens Ecosystem and Compatibility: The Glass Matters

A body is only as good as the glass you mount on it.

Olympus’s OM-5 uses the Micro Four Thirds mount with a gargantuan selection of 119 lenses from Olympus, Panasonic, and third parties. This ecosystem covers fast primes, pro telephotos, and stunning macro optics, typically at more accessible prices than full-frame glass.

The 2.1x crop factor means you get impressive tele reach from modestly priced lenses - great for wildlife and sports on a budget, though you lose some shallow depth-of-field magic.

In contrast, Sony A9 uses the E-mount, with 121 compatible lenses ranging from compact primes to high-end cinema glass. Top-tier lenses like the Sony GM series deliver extraordinary sharpness, wide apertures, and excellent autofocus. The full-frame sensor rewards fast glass with creamy bokeh and low-light prowess but at a premium price.

Of note is Sony’s compatibility with third-party lens makers like Sigma and Tamron, broadening options without breaking the bank - though the cost of the pro-level glass ecosystem still beats Olympus in sheer reach and low-light capability.

Battery Life and Storage: Staying Power in the Field

Photographers (especially professionals) hate running out of juice mid-shoot.

Olympus OM-5’s BLS-50 battery rates for about 310 shots per charge - adequate for casual day trips but requiring spare batteries for a full-day excursion. It supports UHS-II SD cards in its single storage slot, a limiting factor if redundancy or overflow matters to you.

Sony’s A9 is powered by the NP-FZ100 battery, which nearly doubles endurance at 650 shots per charge. Additionally, the dual SD card slots (both UHS-II compatible) add flexibility for overflow, backup, or separating RAW/JPEG files - a must-have for professionals who cannot risk data loss.

Olympus fans will appreciate the OM-5’s compactness, but professionals will see the A9’s battery and storage advantages as essential for uninterrupted shoots.

Connectivity and Workflow Integration: Sharing in the Modern Age

Both cameras have built-in Wi-Fi and Bluetooth for quick image transfer and remote control via apps, but Sony packs a slight edge with NFC support for faster pairing.

Olympus’s USB 2.0 port is limiting compared to newer USB-C standards but supports in-camera charging - a convenience if you travel light and avoid carrying chargers. Sony also has USB 2.0, which is a surprise given its pro status, but works fine for tethered shooting and charging.

In the workflow department, the A9 stands out with deeper integration for studio tethering and faster buffer clearing, essential for event photographers. Meanwhile, the OM-5’s simplicity appeals to travelers and hobbyists who prefer quick sharing without complex setups.

How They Perform Across Photography Genres

Let’s unpack how each camera shines - and stumbles - in specific photographic styles.

OM System OM 5 front OM System OM 5 screen back Sony A9 front Sony A9 screen back

Portrait Photography

• OM-5: Delivers pleasing skin tones and decent background blur given the smaller sensor. Eye detection works reliably in good light but lacks animal eye AF. Its relatively slow burst speed hampers capturing fast facial expressions, but the articulating screen aids creative angles and vlogging.
• A9: Superior eye and animal eye autofocus ensures tack-sharp portraits with gorgeous bokeh, even in challenging lighting. The higher resolution sensor and superior color depth produce rich, nuanced tones. Fast autofocus and high frame rates capture fleeting expressions effortlessly.

Landscape Photography

• OM-5: Compact and weather-sealed, perfect for trail hikes. The 20MP sensor, while smaller, produces good sharpness and dynamic range for web and moderate print sizes. Focus stacking and bracketing modes help enhance detail. The smaller sensor limits ultimate resolution.
• A9: Excels with high resolution, deep dynamic range, and excellent high ISO control. Full-frame sensor delivers cleaner skies and finer textures. Larger file sizes demand more storage and processing power.

Wildlife Photography

• OM-5: The 2.1x crop factor extends telephoto reach, a boon for budget wildlife shooters. Burst speed and AF tracking are decent but not professional-grade. No animal eye AF means missing some critical focus points.
• A9: Fastest burst rate at 20 fps and best-in-class autofocus tracking and animal eye detection make this a top choice for wildlife pros. Larger sensor and better lenses yield clearer, more detailed wildlife shots.

Sports Photography

• OM-5: 10 fps mechanical and 30 fps electronic bursts usable for casual sports. AF performance is solid but may struggle with erratic subjects.
• A9: Outstanding tracking, virtually zero blackout, and deep buffers make it an elite sports camera. Paired with native lenses, it’s a clear winner.

Street Photography

• OM-5: Compact size and lower noise operation make it more discreet. Articulated touchscreen aids versatility in shooting angles.
• A9: Bigger, louder shutter, but excellent focusing speed. Larger body can be less stealthy.

Macro Photography

• OM-5: Excellent focusing bracketing and sensor-shift stabilization support close-up work. Smaller sensor allows greater depth of field at given apertures.
• A9: High resolution and fast lenses shine, but increased shallow depth of field can make focusing more challenging.

Night and Astro Photography

• OM-5: Manages high ISO fairly well but limited by sensor size. Built-in stabilization works well for longer exposures.
• A9: Superior high ISO, dynamic range, and low noise make it ideal for star fields and nightscapes.

Video Capabilities

• OM-5: Offers 4K UHD (2160p) at 24 fps, sensor-based 5-axis stabilization, and mic input but no headphone jack.
• A9: 4K UHD video up to 30 fps, headphone and mic ports, and enhanced processing deliver better professional video options.

Travel Photography

• OM-5: Lightweight, rugged, and versatile - perfect for globetrotters who prioritize decreased bulk.
• A9: Although heavier, excels in versatility and image quality, making it a solid choice for serious travel photographers not daunted by size.

Professional Work

• OM-5: Great backup or secondary body for professionals owing to weather sealing and solid image quality.
• A9: A recognized pro flagship, suitable as a primary body for weddings, sports, events, and commercial photography with high reliability.

Price-to-Performance and Final Ratings

Before we wrap up, let’s talk numbers, because budget (and value) matters.

• OM System OM-5: Around $1,200 USD at launch, it offers compelling value for enthusiasts and semi-pros. It’s versatile, lightweight, and feature-rich for the price.
• Sony Alpha A9: At about $4,500 USD new, it’s undoubtedly an investment aimed at professionals who demand speed, accuracy, and industry-leading image quality.

Given the spectrum of features, the OM-5 scores excellently in portability and versatility but understandably lags behind in speed and sensor performance. The Sony A9 leads in technical prowess, autofocus, battery life, and professional-grade build - at a significant cost premium.

The Bottom Line: Which One Should You Buy?

Picking between the OM System OM-5 and Sony A9 is a quintessential case of "choosing your photographic weapon" based on your priorities.

Choose the OM System OM-5 if:

• You crave a rugged, weather-sealed, pocket-friendly body perfect for travel and everyday shooting.
• Budget-conscious but want a solid sensor with versatile lens options.
• You shoot landscapes, macro, street, or casual sports predominantly.
• Articulated touchscreen for vlogging or shooting at awkward angles is a priority.
• You value image stabilization and easy-to-use interface over raw speed.

Choose the Sony A9 if:

• You are a pro or serious enthusiast shooting demanding subjects like sports, wildlife, or fast-paced events.
• You prioritize best-in-class autofocus with unmatched tracking and eye detection.
• Need a large, bright, and detailed EVF for critical focusing in the field.
• Require excellent high ISO performance and superior full-frame image quality.
• Can invest in high-end glass and appreciate robust battery life and dual card slots.

Final Thoughts: Two Cameras, Different Worlds United by Quality

Both Olympus OM System OM-5 and Sony Alpha A9 hold place and respect in their respective realms. They share weather sealing, in-body stabilization, excellent ergonomics (each in their style), and connectivity enabling modern photographers to keep creating.

While Olympus excels at lightweight agility and affordability with solid image quality, Sony delivers pure technical perfection and pro-level responsiveness crucial for commercial and competitive work.

In my hands, the OM-5 was a reliable travel companion with surprising versatility; the A9, a racecar for the demanding professional chase. No wrong choice - just different adventures.

Whichever you lean toward, both put powerful photography within reach. And if anything, that’s a win for all of us behind the lens.

Happy shooting!

This article was written from extensive hands-on testing, experience with professional workflows, and analysis of industry-standard benchmarks to provide you a trustworthy comparison that helps you capture your best shots.