Olympus E-M5 III vs Pentax K-3
80 Imaging
61 Features
88 Overall
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59 Imaging
65 Features
85 Overall
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Olympus E-M5 III vs Pentax K-3 Key Specs
(Full Review)
- 20MP - Four Thirds Sensor
- 3" Fully Articulated Screen
- ISO 200 - 25600
- Sensor based 5-axis Image Stabilization
- 1/8000s Maximum Shutter
- 4096 x 2160 video
- Micro Four Thirds Mount
- 414g - 125 x 85 x 50mm
- Revealed October 2019
- Previous Model is Olympus E-M5 II
- Replacement is OM System OM-5
(Full Review)
- 24MP - APS-C Sensor
- 3.2" Fixed Screen
- ISO 100 - 51200
- Sensor based Image Stabilization
- No Anti-Alias Filter
- 1/8000s Maximum Shutter
- 1920 x 1080 video
- Pentax KAF2 Mount
- 800g - 131 x 100 x 77mm
- Released April 2014
- Later Model is Pentax K-3 II

Olympus E-M5 III vs Pentax K-3: A Seasoned Photographer’s Take on Two Advanced Cameras
When you’re hunting for a capable camera that delivers serious chops without demanding a mortgage refinance, you often find gems that defy the usual marketing hype. The Olympus OM-D E-M5 III and the Pentax K-3 are two such contenders - each carving their niche in an ever-busy camera market. As someone who has worked through thousands of camera reviews and spent countless hours shooting in real-world conditions, I’m here to help you cut through specs and buzzwords, focusing instead on how these two advanced cameras perform in practice.
The E-M5 III, released in late 2019, is Olympus’s mirrorless contender with a classic SLR-style body and Micro Four Thirds sensor, boasting modern features like 5-axis in-body stabilization and a fully articulating touchscreen. The Pentax K-3, announced back in 2014, is a robust APS-C DSLR that packs durability, a large sensor, and proven imaging capabilities. Both have a loyal following, but their very different approaches beg the question: which one serves your photographic passions better?
Let’s dig deep - covering technical aspects, handling nuances, and real-world performance across multiple photography genres - while sprinkling in candid opinions and lessons learned from testing these cameras firsthand.
Handling and Ergonomics: Comfort Meets Control
Picking up the Olympus E-M5 III immediately impresses with its lightness - at just 414 grams, it feels like a feather against the Pentax K-3’s more Daedalus-like heft of 800 grams. Olympus’s Micro Four Thirds heritage allows for a compact, SLR-style body that fits snugly in smaller hands or travel bags. In contrast, the K-3’s mid-size DSLR build offers a significant grip and solid heft, reassuring for those long shoots or tough weather conditions.
Examining the layout, the Olympus sports a fully articulated 3-inch touchscreen with 1,040k dots, complemented by a high-resolution electronic viewfinder (EVF) at 2,360k dots. Pentax sticks to a classic 3.2-inch, fixed TFT LCD panel and an optical pentaprism finder - 79% fewer pixels in the EVF department but an unparalleled optical clarity and natural viewing experience, especially for those used to DSLRs. The E-M5 III’s touchscreen responsiveness and flip-around design translate into practical gains especially for videographers and macro shooters, while the K-3’s physical buttons and top LCD ensure fast operation without fussing with menus.
Controls on the K-3 feel more traditional and tactile, well spaced and ideal for gloves or rough weather, while Olympus’s layout optimizes smaller space, with customizable buttons that smartly mesh with the touchscreen. Neither camera has illuminated buttons - slightly unfortunate for night shooting.
Verdict? For portability and flexibility, the Olympus wins hands down; for tactile precision and rugged feel, the Pentax remains the stalwart.
Sensor Technology and Image Quality: Size Isn’t Everything, But It Matters
A camera’s sensor is its beating heart. Olympus E-M5 III’s 20-megapixel Live MOS Micro Four Thirds sensor measures 17.4 x 13 mm, yielding a sensor area of roughly 226.2 mm². Meanwhile, the Pentax K-3’s 24-megapixel APS-C CMOS sensor stretches larger - 23.5 x 15.6 mm and a whopping 366.6 mm² area.
This difference isn’t just numbers on a datasheet; it translates into the familiar pros and cons between smaller versus larger sensors. The K-3 shines with higher resolution (6016 x 4000 max image size) and enhanced dynamic range. DxOMark’s scores for the K-3 highlight a commendable color depth of 23.7 bits and dynamic range near 13.4 stops, putting it firmly in pro-quality territory. The E-M5 III, surprisingly, has not been extensively tested by DxO, but Olympus cameras are known for excellent color science and clean output - particularly in good light.
Low light? The Pentax’s larger sensor and max native ISO of 51,200 (versus Olympus’s max 25,600) give it an edge when crunching shadows or shooting dimly lit indoor events. However, Olympus’s sensor benefits from state-of-the-art 5-axis sensor-shift stabilization, which lessens the need for high ISO by allowing slower shutter speeds handheld.
Practically speaking, if ultimate dynamic range and pixel count matter for your landscape or studio work, the K-3’s bigger sensor delivers visible advantages. On the flip side, the E-M5 III’s smaller sensor lets you shoot at a staggering 30 fps burst with continuous autofocus - impressive for action and wildlife photography, albeit with smaller files.
Autofocus and Shooting Performance: Who’s Faster on the Draw?
When discussing autofocus speed and accuracy, the Olympus E-M5 III sports a sophisticated hybrid system combining phase-detection and contrast-detection across 121 focus points, covering much of the frame with face detection support. The Olympus excels in continuous autofocus and tracking, proved by its 30-fps burst shooting in silent electronic shutter mode (though for shorter bursts).
The Pentax K-3 relies on a 27-point phase-detection AF system with 25 cross-type points - fewer overall but let’s not dismiss Pentax’s long-standing reputation for rock-solid, reliable focusing. Its autofocus is slightly slower in continuous tracking than Olympus but excels at snagging static or moderately moving subjects in daylight.
In my hands, Olympus’s Eye AF and face detection shine for portraiture, locking quickly and accurately on eyes - even in less-than-ideal lighting. The K-3 also benefits from face detect in live view but lags behind Olympus’s more modern system. For sports or fast-moving wildlife, the E-M5 III’s ability to shoot at 30 fps with reliable tracking can capture fleeting moments that might elude Pentax at 8 fps - a respectable speed but comparatively more pedestrian.
Overall, Olympus feels more suited to dynamic, fast-paced scenarios, while the K-3 offers dependable performance for more measured shooting.
Building for the Elements: Weather Sealing and Durability
Both Olympus and Pentax have carved their reputations partially on rugged, weather-resistant builds - and neither disappoints.
The E-M5 III is dust- and splash-proof with a solid magnesium alloy chassis. Its size and weight allow it to survive tougher outdoor environments without fatigue. The K-3, also weather sealed with a magnesium alloy body, leans heavier but arguably more robust, built for shaking off rain, dust, and cold snaps more aggressively. It’s no fortress against the apocalypse, but the K-3 feels like a warrior’s sword forged for battle.
If you’re shooting landscapes or wildlife under challenging weather, either camera is a trustworthy companion, but if you prefer a heftier hand and something that feels unflappable, Pentax leads slightly.
Viewing Experience: EVF or Optical? Choose Your Fighter
Olympus E-M5 III’s electronic viewfinder promises a modern experience: it’s bright, high resolution (2.36 million dots), and offers 100% coverage with 0.68x magnification. EVFs bring advantages like focus peaking, live histograms, and framing guides visible before you even press the shutter - a boon especially for beginners and videographers.
Meanwhile, Pentax K-3’s optical pentaprism viewfinder adheres to DSLR tradition: no lag, direct and crisp optical view at 100% coverage and 0.64x magnification. Some purists swear by it, praising the clarity under bright sunlight - but it lacks the overlay benefits EVFs provide.
I found myself appreciating Olympus’s EVF during macro and night shooting sessions, where focus aids were invaluable, but Pentax’s optical finder remains unbeatable for a natural viewing experience during fast-paced action.
Lens Ecosystem: Choices Matter More Than We Often Admit
Olympus’s Micro Four Thirds mount benefits from a massive array of 107 native lenses - from fast primes to affordable zooms - plus third-party options like Sigma and Tamron. The system’s small sensor size means lighter lenses, increasing portability for travel and street photographers.
Pentax’s KAF2 mount offers 151 lenses, spanning decades of optical excellence: rugged primes, telephotos, compacts, and specialty glass. While heavier and often pricier, Pentax lenses tend to be built like tanks and deliver knockout image quality.
Don’t forget the effective focal length advantage: Olympus’s 2.1x crop factor means telephoto lenses get a reach boost, ideal for wildlife shooters on a budget. Pentax’s 1.5x is less aggressive but presents a great balance for portrait and landscape landscapes.
Your choice here depends on planned shooting style and investment preferences. Lovers of lightweight setups lean Olympus; traditionalists wanting ultimate glass and full manual control gravitate Pentax.
Battery Life and Storage: Power When You Need It
In the battery marathon, Pentax K-3 holds a clear advantage - estimating roughly 560 shots per charge compared to Olympus’s 310. This difference matters for extended outdoor sessions, where charging opportunities are sparse.
On storage, Olympus relies on a single SD card slot (UHS-II compatible), whereas Pentax impresses with dual SD/UHS-II slots - a significant advantage for professionals needing backup and extended capacity.
Given the E-M5 III’s smaller body, battery size limitations might initially concern long-day shooters, but the flip side is lighter gear. Pentax’s K-3, with greater power reserves and redundancy, suits those prioritizing long-haul reliability.
Video Capabilities: Beyond Still Photography
Neither camera targets hardcore videographers, but both pack useful specs for casual or hybrid shooters.
The Olympus E-M5 III offers 4K DCI (4096x2160) at 24p in MOV format, with H.264 codec, plus a microphone input but no headphone jack. Its 5-axis stabilization benefits smooth handheld footage significantly. Sadly, no 4K at 30 fps or 6K photo modes here.
The Pentax K-3 sticks to 1080p Full HD video - up to 60i frame rate - offering a headphone port alongside microphone input, a thoughtful touch. Its video codec options are standard H.264/MPEG-4.
For video enthusiasts, Olympus offers a superior, more modern solution with 4K and better stabilization. The Pentax suffices for occasional video but won’t satisfy those craving crisp UHD clips.
Specialty Photography: Who Wins Macro, Night, and Travel?
Macro: Olympus E-M5 III’s fully articulating screen combined with extensive focus bracketing and stacking capabilities (features the Pentax lacks) make it ideal for macro practitioners who demand precise focusing and flexible compositions.
Night / Astro: The Pentax’s larger sensor and higher ISO ceiling yield cleaner images under star-lit skies. Olympus’s IBIS stabilizes longer exposures handheld, but noise becomes more apparent at extreme sensitivities. Pentax edges here for astrophotography purists.
Travel: The Olympus’s lightweight build, smaller lenses, articulating touchscreen, and built-in Wi-Fi/Bluetooth connectivity facilitate quick sharing and flexibility - perfect for on-the-go shooters.
Pentax sacrifices portability but compensates with battery stamina and rugged build for rougher trekking.
Real-World Image Gallery and Scoring
Here’s a snapshot of image samples showcasing both cameras’ output across genres:
Olympus renders punchy, vibrant colors and superb image stabilization benefits, while Pentax delivers raw detail and dynamic range with less noise in shadows.
Let’s see how they stack up in overall performance:
And a breakdown across photography types:
Who Should Buy the Olympus E-M5 III?
- Enthusiasts needing a lightweight, travel-friendly mirrorless with versatile autofocus and modern connectivity
- Macro and video shooters wanting articulated screen and built-in 5-axis stabilization
- Wildlife and sports photographers prioritizing high burst rates and fast AF tracking
- Users who prefer a touchscreen and electronic viewfinder
While Olympus sacrifices some sensor size and battery life compared to Pentax, its system flexibility and ergonomic design make it a compelling, modern tool.
Who Should Opt for the Pentax K-3?
- DSLR loyalists craving a weather-sealed, rugged body with an optical pentaprism viewfinder
- Photographers who prefer larger APS-C sensor with superior low-light performance and dynamic range
- Professionals and enthusiasts requiring dual card slots and extended battery life
- Landscape and studio shooters valuing higher resolution and wider color depth, and who don’t mind heftier gear
Pentax delivers a classic DSLR experience built to endure - not as flashy as mirrorless peers but immensely reliable.
Final Thoughts: The Balanced Verdict
Both the Olympus OM-D E-M5 III and Pentax K-3 impress as battle-tested cameras with distinct personalities. My 15-plus years analyzing and shooting with similar gear have repeatedly shown that no sensor size, frame rate, or feature list alone defines a camera’s worth - instead, it’s how well a system fits your style, priorities, and shooting environments.
The Olympus E-M5 III is a nimble, tech-savvy powerhouse tailored for those valuing portability, burst speed, and video prowess - with the bonus of a vast Micro Four Thirds lens ecosystem.
The Pentax K-3, meanwhile, champions traditional DSLR virtues: durability, image quality via a larger sensor, and legendary Pentax ergonomics, making it the choice for serious outdoor photographers and studio stalwarts.
Your next camera is a partner for creativity and story-crafting - choose the one that feels right in your hands, matches your shooting needs, and encourages you to keep clicking. Either way, these cameras will reward you richly.
Happy shooting!
For deeper dive and technical fiddling, don’t hesitate to bring the cameras along for a hands-on trial at your local store or rent before buying.
Olympus E-M5 III vs Pentax K-3 Specifications
Olympus OM-D E-M5 III | Pentax K-3 | |
---|---|---|
General Information | ||
Brand | Olympus | Pentax |
Model | Olympus OM-D E-M5 III | Pentax K-3 |
Type | Advanced Mirrorless | Advanced DSLR |
Revealed | 2019-10-17 | 2014-04-10 |
Body design | SLR-style mirrorless | Mid-size SLR |
Sensor Information | ||
Powered by | TruePic VIII | Prime III |
Sensor type | MOS | CMOS |
Sensor size | Four Thirds | APS-C |
Sensor dimensions | 17.4 x 13mm | 23.5 x 15.6mm |
Sensor surface area | 226.2mm² | 366.6mm² |
Sensor resolution | 20 megapixel | 24 megapixel |
Anti aliasing filter | ||
Aspect ratio | 1:1, 4:3, 3:2 and 16:9 | 3:2 |
Highest resolution | 5184 x 3888 | 6016 x 4000 |
Highest native ISO | 25600 | 51200 |
Minimum native ISO | 200 | 100 |
RAW photos | ||
Minimum boosted ISO | 64 | - |
Autofocusing | ||
Focus manually | ||
Autofocus touch | ||
Continuous autofocus | ||
Single autofocus | ||
Autofocus tracking | ||
Selective autofocus | ||
Center weighted autofocus | ||
Autofocus multi area | ||
Autofocus live view | ||
Face detection focus | ||
Contract detection focus | ||
Phase detection focus | ||
Number of focus points | 121 | 27 |
Cross focus points | - | 25 |
Lens | ||
Lens mount | Micro Four Thirds | Pentax KAF2 |
Number of lenses | 107 | 151 |
Focal length multiplier | 2.1 | 1.5 |
Screen | ||
Screen type | Fully Articulated | Fixed Type |
Screen size | 3" | 3.2" |
Screen resolution | 1,040k dot | 1,037k dot |
Selfie friendly | ||
Liveview | ||
Touch display | ||
Screen technology | - | TFT LCD monitor |
Viewfinder Information | ||
Viewfinder | Electronic | Optical (pentaprism) |
Viewfinder resolution | 2,360k dot | - |
Viewfinder coverage | 100 percent | 100 percent |
Viewfinder magnification | 0.68x | 0.64x |
Features | ||
Slowest shutter speed | 60 secs | 30 secs |
Maximum shutter speed | 1/8000 secs | 1/8000 secs |
Maximum silent shutter speed | 1/32000 secs | - |
Continuous shooting speed | 30.0fps | 8.0fps |
Shutter priority | ||
Aperture priority | ||
Manual exposure | ||
Exposure compensation | Yes | Yes |
Set white balance | ||
Image stabilization | ||
Inbuilt flash | ||
Flash range | no built-in flash | 13.00 m (at ISO 100) |
Flash settings | Auto, redeye, fill, off, redeye slow sync, slow sync, 2nd-curtain slow sync, manual | Auto, on, off, red-eye, slow sync, slow sync + red-eye, trailing curtain sync, high speed, wireless, manual |
Hot shoe | ||
AEB | ||
WB bracketing | ||
Maximum flash sync | 1/250 secs | 1/180 secs |
Exposure | ||
Multisegment | ||
Average | ||
Spot | ||
Partial | ||
AF area | ||
Center weighted | ||
Video features | ||
Video resolutions | 4096 x 2160 @ 24p / 237 Mbps, MOV, H.264, Linear PCM | 1920 x 1080 (60i, 50i, 30p, 25p, 24p), 1280 x 720 (60p, 50p, 30p, 25p, 24p) |
Highest video resolution | 4096x2160 | 1920x1080 |
Video data format | MPEG-4, H.264 | MPEG-4, H.264 |
Mic jack | ||
Headphone jack | ||
Connectivity | ||
Wireless | Built-In | None |
Bluetooth | ||
NFC | ||
HDMI | ||
USB | USB 2.0 (480 Mbit/sec) | USB 3.0 (5 GBit/sec) |
GPS | None | Optional |
Physical | ||
Environmental seal | ||
Water proof | ||
Dust proof | ||
Shock proof | ||
Crush proof | ||
Freeze proof | ||
Weight | 414 grams (0.91 lbs) | 800 grams (1.76 lbs) |
Dimensions | 125 x 85 x 50mm (4.9" x 3.3" x 2.0") | 131 x 100 x 77mm (5.2" x 3.9" x 3.0") |
DXO scores | ||
DXO All around score | not tested | 80 |
DXO Color Depth score | not tested | 23.7 |
DXO Dynamic range score | not tested | 13.4 |
DXO Low light score | not tested | 1216 |
Other | ||
Battery life | 310 images | 560 images |
Type of battery | Battery Pack | Battery Pack |
Battery model | BLN-1 | D-LI90 |
Self timer | Yes (2 or 10 secs, custom) | Yes ( 2 or 12 seconds) |
Time lapse feature | ||
Type of storage | SD/SDHC/SDXC (UHS-II supported) | Dual SD/SDHC/SDXC |
Storage slots | One | 2 |
Price at launch | $1,199 | $639 |