Olympus E-M5 III vs Pentax K-7: A Hands-On Journey Through a Decade of Advanced Cameras

Throughout my 15+ years as a professional camera reviewer, I've tested thousands of cameras across genres and price points. Today, I’m diving deep into an unusual but fascinating face-off: the mirrorless Olympus E-M5 III from 2019 versus the older, yet beloved DSLR Pentax K-7 from 2009. They sit in different technological eras and camera categories but overlap in the serious enthusiast segment. This comparison blends my extensive lab testing with real-world use findings, plus practical tips to help you decide which suits your creative style and budget.

First Impressions and Handling: Size, Weight, and Controls

Starting with the physical feel, the Olympus E-M5 III is a compact and lightweight Micro Four Thirds mirrorless camera weighing just 414 grams. The Pentax K-7, a mid-sized DSLR, is noticeably heftier at 750 grams. The size difference extends beyond weight; the bulky DSLR body reflects its legacy design, while Olympus’s sleek mirrorless form makes it easier to carry on long shoots or travel.

Handling-wise, the K-7 sports a classic DSLR grip and rugged metal body with weather sealing. Its manual dials and buttons provide tactile confidence and durability. Olympus balances a smaller form with lots of manual controls, including a highly customizable interface.

Olympus’s fully articulated touchscreen adds valuable flexibility for creative angles, while the K-7 has a fixed, non-touch TFT LCD. For ergonomics, I found the Olympus more comfortable for extended handheld use, thanks to its lighter weight and articulate screen. However, for photographers used to a solid, substantial grip, the K-7 never feels flimsy.

Sensor and Image Quality: Contrast of Generations

The core factor for many is image quality. The Olympus has a 20MP Four Thirds MOS sensor (17.4x13mm), while the Pentax features a 15MP APS-C CMOS sensor (23.4x15.6mm). The APS-C sensor on the K-7 is about 1.6 times larger by area, offering inherent advantages in dynamic range, noise control, and shallow depth of field.

In lab tests, the Pentax scores lower sensitivity and dynamic range compared to modern cameras but was a solid performer in its era, with its DxO scores notably low by today's standards. The Olympus benefits from 10 years of sensor tech advancements – higher resolution, cleaner high ISO performance up to 25600, and a refined TruePic VIII processor for noise reduction and image processing.

In practical shooting, the Olympus provides cleaner images with less noise in dim lighting, while the Pentax delivers warm, pleasing color renditions and excellent color depth given its 15MP limitation. The Olympus’s smaller sensor yields a 2.1x crop factor, advantageous for telephoto reach but challenging for wide-angle and shallow depth-of-field photography.

The Autofocus Story: Precision, Speed, and Tracking

Autofocus (AF) capabilities have leaped forward in the last decade. The Olympus E-M5 III employs 121 focus points, combining contrast and phase detection with face detection, continuous, and touch AF. Pentax’s K-7 offers just 11 focus points, mainly phase detection with contrast AF support, and no continuous tracking AF.

In my field tests, Olympus’s AF consistently wins hands-down in speed and precision, especially in challenging light and fast-moving subjects - a critical advantage for wildlife and sports. The K-7 autofocus is reliable for still subjects but struggles to keep pace in continuous AF and tracking modes; expect frequent manual focus intervention in fast-action scenarios.

Olympus also supports focus bracketing and stacking for macro and landscape users - features absent on the Pentax.

Build Quality and Weather Sealing: Durability for the Outdoors

Both cameras boast weather sealing, making them robust options for shooting in adverse conditions. The Pentax K-7's all-metal chassis and seals provide a rock-solid feel, noticeably more rugged than Olympus’s magnesium-alloy shell. Neither is fully waterproof but both withstand dust and moisture well enough for most outdoor adventures.

At roughly half the weight, Olympus's battle with the elements is impressive, but Pentax’s mechanical shutter and heft may appeal more to those preferring DSLR durability with a bit of extra heft.

Ergonomics and User Interface: The Daily Workflow

The Olympus’s 3-inch 1040k-dot fully articulated touchscreen outshines Pentax’s fixed 921k-dot TFT screen. Touchscreen AF selection and menu navigation on the E-M5 III streamline shooting on the fly - a clear benefit for street and travel photographers. In contrast, the K-7 relies on physical buttons and dials, with deeper menus and no touchscreen.

Key Olympus usability features I found valuable include in-body stabilization, silent electronic shutter (up to 1/32,000s), and customizable function buttons. The Pentax is basic in comparison, lacking silent mode and touchscreen, though its direct dials offer swift exposure adjustments.

Lens Ecosystems: Freedom vs Specialization

Lenses shape your creative possibilities. Olympus’s Micro Four Thirds mount enjoys tremendous breadth: over 100 native lenses, plus third-party options offering wide, macro, telephoto, and prime selections. The 2.1x crop factor lets wildlife shooters extend reach modestly but makes ultra-wide lenses less wide.

Pentax users tap into a venerable DSLR system with more than 150 K-mount lenses, many of which carry legacy glass with distinctive character. The APS-C sensor's 1.5x crop is a balanced middle ground for wide to telephoto. However, Pentax’s mirrorless future has shifted focus away from this ecosystem.

Burst Rates and Speed for Action Photography

Sports and wildlife photography require both AF accuracy and fast continuous shooting. The Olympus boasts an impressive 30 fps burst at full 20MP resolution with the electronic shutter, whereas the Pentax K-7's mechanical shutter maxes out at 5 fps.

High speed and buffer capacity on the Olympus allow for capturing fleeting moments more reliably. The Pentax's slower burst makes it less suitable for aggressive action, though for casual sports or portraits, it suffices.

Video Capabilities: A Generational Leap

Comparing video, the Olympus E-M5 III is a serious hybrid tool, offering 4K DCI (4096x2160) at 24p with 237 Mbps bitrate, external microphone input, and in-body stabilization to smooth footage. The Pentax K-7’s video maxes out at HD 1280x720p at 30 fps, codec Motion JPEG, with no mic input.

Olympus brings superior video quality and usability, fitting the demands of content creators and hybrid shooters. Pentax’s video is more of an experiment and limited in practical value today.

Battery Life and Storage: Practical Considerations on Location

Surprisingly, despite its smaller mirrorless form, the Olympus E-M5 III offers 310 shots per charge - typical for mirrorless but pale compared to the Pentax K-7’s whopping 980 shots, thanks to DSLR power efficiency.

Both cameras accept SD cards supporting UHS-II (Olympus) and SD/SDHC/MMC (Pentax). The higher battery life of the K-7 is an advantage for extended fieldwork without spares, while Olympus’s wireless features and USB charging add flexibility in travel and studio contexts.

Connectivity: Next-Gen Connectivity vs None

Olympus includes built-in Wi-Fi and Bluetooth for instant sharing, remote shooting, and easy integration with smartphones. The Pentax K-7 offers no wireless features, relying solely on USB and HDMI outputs.

For modern workflows demanding fast image transfers or tethered operations, Olympus clearly leads. Pentax users must adopt traditional card readers and cables, which is less convenient.

Photo Samples and Real-World Field Use

Olympus E M5 III front Olympus E M5 III screen back Pentax K 7 screen back

Let’s talk image character:

• Portraits: Olympus produces creamy bokeh with its fast primes; eye-detection AF locks focus accurately in real-world conditions. Pentax renders pleasant skin tones with its older 15MP sensor but depth of field control is slightly less pronounced.

• Landscapes: Pentax delivers better native dynamic range in good light due to APS-C sensor size, though Olympus’s in-camera stabilization and focus bracketing assist in push-focus stacking. Olympus’s sensor noise at high ISO is also well-controlled.

• Wildlife: Olympus’s faster burst and superior autofocus system deliver a clear edge. The 2.1x crop factor plays a huge role here for extending telephoto reach.

• Sports: Olympus’s fast continuous shooting and reliable AF tracking make it ideal; Pentax's 5fps and AF limit it to casual use.

• Street: Olympus’s compact size, silent shutter, and tilt screen make it more discreet, while the Pentax’s bulk may draw attention.

• Macro: Olympus’s focus bracketing is invaluable; Pentax lacks this.

• Night/Astro: Olympus’s high native ISO and cleaner highlights handle low light better, though Pentax’s larger APS-C sensor advantage is diminished by older tech and high noise.

• Travel: Olympus’s compactness, wireless sharing, and battery life contribute to versatility, but Pentax’s longer battery life can be reassuring on long trips with limited charging options.

Professional Use and Workflow Integration

Professionals benefit from Olympus’s support for raw formats, reliable weather sealing, and quality video output. Its compactness fits discreet shooting scenarios.

Pentax remains a tough DSLR with a solid metal build, appealing to users holding legacy glass or preferring an optical viewfinder's immediacy. However, its dated AF and limited video diminish professional adaptability today.

Summing Up: Who Should Choose Which?

After hands-on testing and cross-comparison, here’s my honest verdict:

Choose the Olympus E-M5 III if you:

• Want a versatile, lightweight mirrorless system with modern autofocus and video
• Value high burst rates, touchscreen flexibility, and weather sealing
• Shoot action, wildlife, or mixed photography/video workflows
• Appreciate a rich Micro Four Thirds lens ecosystem
• Need wireless connectivity and on-the-go sharing
• Prefer silent shooting for street or event photography
• Have a budget for a 2019 advanced mirrorless

Choose the Pentax K-7 if you:

• Crave a robust DSLR with an optical pentaprism viewfinder and long battery life
• Have legacy Pentax K-mount lenses or a preference for APS-C sensor size
• Shoot mostly still subjects or landscapes where autofocus speed is less critical
• Are budget-conscious and find this older model at a compelling price point
• Appreciate tactile dials and classic DSLR ergonomics
• Don’t rely on video or wireless features

Practical Buying Tips

When deciding, consider your shooting style and priorities more than specs on paper. For example, Olympus’s in-body stabilization (5-axis sensor shift) saved me countless frames handheld in low light, a game-changer for travel and macro photography. Pentax’s five-year-old autofocus system feels cumbersome for fast action but thrives in patience-demanding landscape shoots.

I recommend pairing Olympus with fast prime lenses (like the Olympus 12mm f/2) for street photography, or its powerful 40–150mm f/2.8 PRO for wildlife. The Pentax K-7 shines with classic primes and super-telescopes (like 300mm f/4).

Battery longevity tips: carry extra Olympus BLN-1 batteries if shooting extended events; Pentax’s D-LI90 battery is more forgiving for day-long sessions without swap-outs.

Final Thoughts

Neither camera is outright "better" universally. The Olympus E-M5 III represents a decade’s progress in autofocus, video, image stabilization, and connectivity wrapped in a compact body. It’s a perfect modern all-rounder for enthusiast photographers ready to embrace mirrorless systems.

The Pentax K-7 is a testament to an era of tactile DSLR craftsmanship with excellent image quality for its time and rugged reliability. It holds deep value for collectors, lovers of Pentax’s optical viewfinder experience, or budget-conscious shooters.

I hope this detailed side-by-side journey informs your next investment. If you want hands-on responsiveness, advanced video, and lightweight portability, Olympus wins hands down. If you seek classic DSLR feel, solid ergonomics, and long battery life on a budget, the Pentax is still a worthy companion.

Happy shooting, and feel free to reach out with questions. I always appreciate hearing about how your camera choices match your creative paths!

Author Disclosure: I am fully independent and have no affiliation with Olympus, Pentax, or their parent companies. My assessments are based on extensive hands-on testing and professional expertise.