Olympus OM-D E-M1 vs Pentax K100D: A Real-World Battle of Past and Present Photography Classics

Choosing the right camera can be daunting - especially when you’re comparing two gear legends as different as the Olympus OM-D E-M1, a 2013 pro-level mirrorless marvel, and the Pentax K100D, a 2006 entry-level DSLR workhorse. Each represents a distinct era and philosophy in camera design, technology, and user experience. I’ve spent considerable hands-on time testing both cameras across various photography scenarios to provide you with an authoritative, experience-driven comparison. If you’re weighing these two cameras for your creative pursuits, this article will help you understand their core strengths, limitations, and which might best serve your needs.

Let’s dive into all critical aspects - from sensor capabilities and autofocus to handling and genre-specific performance - informing your decision with balanced insights and practical advice.

Size & Ergonomics: Feel the Difference in Your Hands

The tactile experience of a camera often makes or breaks your shooting enjoyment. Olympus’s OM-D E-M1 is a compact, mirrorless beast designed for mobility and professional handling, while the Pentax K100D sticks to the traditional DSLR form with a bulkier, somewhat dated feel.

Olympus E-M1 offers an SLR-style, mirrorless body that weighs just 497g with dimensions of 130x94x63mm. It’s far more pocketable and travel-friendly, benefiting from a magnesium alloy shell and thoughtful ergonomics that support long shoots without fatigue.

The Pentax K100D tips the scales at 660g and measures 129x93x70mm. Its body feels more substantial, owing to the mirror box assembly, but also noticeably heavier and chunkier in hand. This may appeal to traditional DSLR fans valuing a firm grip but can tire you during extended handheld use.

Personally, I found the E-M1’s deeply contoured grip and lighter weight made it my go-to for street and travel photography, where carrying comfort is paramount. The K100D remains serviceable but feels like a relic in this area.

Design Language & Controls: Intuitive vs. Traditional

Understanding button layout and operational flow saves precious shooting time. Here’s a top-level look at their control schemes.

Olympus E-M1 sports a well-laid-out interface with a clear top LCD, customizable function buttons, and dual command dials catering to rapid manual exposure adjustments. The tilting touchscreen is responsive, providing quick access to menus and touch AF functionality - features that modern shooters will appreciate.

On the other hand, the Pentax K100D features a simpler design with fewer direct control surfaces, relying heavily on traditional command dials and an optical pentamirror viewfinder for setting review. Its fixed 2.5" LCD is modest in resolution and functionality - no touchscreen, no live view, and limited feedback beyond basic shooting info.

During my tests, the E-M1’s interface allowed more seamless navigation in complex lighting or fast-moving scenes. For beginners comfortable with old-school DSLRs, the K100D is straightforward but lacks modern conveniences that professionals and enthusiasts expect today.

Sensor Technology & Image Quality: Old School CCD vs. Modern Live MOS

The heart of any camera is its sensor and image processor. This is where big leaps have been made between these two models.

• Olympus E-M1: 16MP Four Thirds Live MOS sensor, measuring 17.3x13mm, paired with the TruePIC VII processor.
• Pentax K100D: 6MP APS-C CCD sensor at 23.5x15.7mm.

The E-M1 packs almost triple the pixels and benefits from a more advanced sensor design and image pipeline, delivering sharper images with cleaner high ISO performance. Four Thirds sensors are smaller than APS-C but Olympus's technology compensates with excellent noise control and dynamic range, rated at 12.7 EV on DxOMark, which is impressive for its class.

The K100D’s CCD sensor, while larger, maxes out at 6MP and peaks at ISO 3200 but with significantly more noise. Its limited resolution and dynamic range mean it’s less flexible in post-processing and falls behind for ultra-detailed work like large prints or cropping-heavy wildlife shots.

Here’s the rub: if ultimate image quality and low-light performance are priorities - especially for demanding portraits or landscapes - the E-M1 pulls ahead decisively. However, the K100D’s sensor can still capture decent images under good lighting conditions.

Viewing Experience: Electronic Precision Meets Optical Simplicity

Having a clear, accurate viewfinder is a critical aspect of composing and focusing your shots.

• The Olympus E-M1’s electronic viewfinder (EVF) offers a high 2.36 million-dot resolution with 100% coverage and 0.74x magnification, providing a bright, real-time exposure preview and focus peaking aids.
• In contrast, the Pentax K100D’s optical pentamirror viewfinder has approximately 96% coverage and lower magnification at 0.57x, typical for entry-level DSLRs of its era.

From firsthand experience, the E-M1’s EVF gives you confidence when shooting in tricky lighting or with manual focus lenses. It displays exposure, histograms, and focus information overlay, helping nail critical portraits and landscape details.

The K100D’s optical viewfinder is comfortable and lag-free but lacks preview feedback, requiring more guesswork when setting exposure - a potential challenge for less experienced users.

Autofocus Systems: Speed, Accuracy, and Tracking Capability

Autofocus reliability and responsiveness are paramount for wildlife, sports, and everyday shooting.

• Olympus E-M1 features an 81-point hybrid AF system (both phase and contrast-detection) with face detection but no animal eye AF.
• Pentax K100D has an 11-point phase detection AF system without live view support or face detection.

While the K100D was decent for its time, providing reliable single-point focus in good light, it falters in accuracy and speed compared to modern standards. Continuous autofocus and tracking are very limited, making it ill-suited for fast action photography.

In contrast, the E-M1’s hybrid system allows faster focusing and smoother continuous AF, especially in challenging conditions. Although lacking advanced animal eye AF now common in newer models, its face detection works well for portrait shooters.

I observed markedly fewer missed shots and faster lock times on the Olympus during wildlife and street photography sessions.

Burst Shooting & Buffer: Capturing the Decisive Moment

Action photographers often rely on frame rates and buffer depth to freeze critical moments.

• The Olympus E-M1 offers 10 fps continuous shooting.
• The Pentax K100D lags with a mere 3 fps burst rate.

The E-M1’s higher frame rate translates into more reliable image sequences to select from in sports, wildlife, or fast-paced events. Additionally, its faster processor handles burst writing efficiently.

If action photography is a focus, E-M1’s performance edge is substantial.

Image Stabilization: Five-Axis Sensor-Based Brilliance

Both cameras feature in-body stabilization, but with stark differences.

• Olympus provides sensor-based 5-axis image stabilization, mitigating camera shake across pitch, yaw, roll, and x-y axes.
• Pentax K100D offers simpler sensor shift stabilization but with less sophistication and effectiveness.

In practice, the Olympus’s 5-axis IS shines when shooting handheld in low light or doing macro work - allowing slower shutter speeds without blur. This feature is a standout advantage over the older Pentax system.

Video Capabilities: From Silent Shoots to Dynamic Capture

Shooting video remains important for many photographers.

• The Olympus E-M1 supports 1080p Full HD at 30 fps, encoded in H.264 and Motion JPEG formats with a microphone input.
• The Pentax K100D offers no video recording option.

If video recording is a consideration - even casual usage - the E-M1 is the clear choice.

Battery Life & Storage: Powering Your Creative Day

Good battery life and storage support are foundational for fieldwork.

The Olympus uses the BLN-1 battery pack delivering approximately 350 shots per charge, typical of mirrorless cameras but shorter than many DSLRs. It stores images on one SD/SDHC/SDXC card slot.

The Pentax relies on 4x AA batteries, which may be convenient for emergency swaps but not cost-effective or environmentally friendly. Its battery life isn’t specified but generally AA performance is variable. Storage uses SD or MMC cards.

Lens Ecosystem & Compatibility: Optics That Grow With You

Your camera is only as powerful as the lenses available.

Olympus E M1 front Olympus E M1 screen back Pentax K100D front Pentax K100D screen back

• Olympus E-M1 uses the Micro Four Thirds mount with over 100 native lens options. This system benefits from excellent modern glass, compact designs, and plentiful third-party backups.
• Pentax K100D accepts Pentax KAF mount lenses, with a historic depth of 151 lenses including many legacy and affordable primes. However, many newer autofocus lenses designed for later bodies may have limited compatibility.

Whether you value compact, high-quality primes and zooms (Olympus) or an expansive catalog of vintage and budget optics (Pentax), both systems can be built into versatile kits - but the MFT ecosystem is more future-proof and tech-forward.

Weather Sealing & Durability: Built for the Shooter’s Environment

The Olympus E-M1 boasts environmental sealing, making it dust and splash resistant - great for outdoor, landscape, and wildlife shooting in harsh conditions.

The Pentax K100D has no weather sealing, limiting its rugged use.

Real-World Photography Performance: Strengths Across Genres

To encapsulate their usability, let’s explore how each camera fares in popular photography disciplines.

Portrait Photography

Landscape Photography

Wildlife & Sports Photography

Street & Travel Photography

Macro & Night/Astro Photography

Video Shooters

Connectivity & Workflow Integration

The Olympus E-M1 includes built-in Wi-Fi for remote control and quick image transfer, HDMI output for external monitors, and USB 2.0.

The Pentax K100D has only USB 2.0 with no wireless or HDMI options.

Whether you are a professional integrating your workflow or an enthusiast sharing images on the fly, the E-M1 far outpaces the older Pentax.

Price-to-Performance: What’s the Best Value?

As of the latest evaluations, the Olympus E-M1 is available around $799 used or refurbished, representing excellent bang-for-buck when considering its advanced feature set and image quality.

The Pentax K100D is largely discontinued and often only attainable used or as collectors’ gear, generally valued below $100 but with significant technological limitations.

For budget-conscious buyers prioritizing basic DSLR operation and optics, the K100D can be adequate. Otherwise, investing in the E-M1 offers a much more future-ready platform with enhanced versatility.

Genre-Specific Performance Ratings: A Visual Summary

Below is a detailed comparison chart mapping each camera’s performance across photography genres, reflecting my testing results.

Final Thoughts & Recommendations

Olympus OM-D E-M1: Who Should Buy This?

• Enthusiasts and professionals seeking a compact, versatile, mirrorless system.
• Photographers requiring stellar autofocus, image stabilization, and video capabilities.
• Those planning to shoot portraits, landscapes, wildlife, sports, or macro with modern lens options.
• Users valuing ruggedness, weather sealing, and connectivity features.
• Photographers who want great battery life in a lightweight body, with fast burst shooting and precise control.

Pentax K100D: Who Might Consider This Camera?

• Beginners satisfying basic photographic curiosity on a tight budget.
• Fans and collectors of Pentax DSLR heritage, appreciating vintage glass compatibility.
• Photographers prioritizing optical viewfinder experience and simplicity over modern features.
• Those shooting primarily in well-lit conditions where lower sensitivity and resolution suffice.

How I Tested - Methodologies That Matter

My evaluations involve putting cameras through multiple real-world tests across different lighting and action conditions:

• Portraits shot with both prime and zoom lenses to inspect skin tone accuracy and bokeh quality.
• Landscapes taken during challenging light to evaluate dynamic range and detail resolution.
• Wildlife and sports settings to gauge autofocus responsiveness and burst reliability.
• Street and travel scenarios emphasizing portability, interface speed, and stealth.
• Macro and night/astro work to test stabilization and high-ISO noise resilience.
• In addition, extensive video recording tests measure stabilization and audio clarity on the Olympus.

These hands-on processes ensure the recommendations reflect practical use, not just spec sheet comparison.

Trustworthy Guidance for Your Next Camera

Both the Olympus OM-D E-M1 and Pentax K100D have carved out their places in photography history. Deciding between them boils down to your creative goals, budget, and tech expectations.

If you seek modern features, superior performance, and future expandability, the Olympus E-M1 remains a highly capable tool even years after release. Conversely, the Pentax K100D offers an accessible entry point into DSLR photography, ideal for those content with foundational features and classic operation.

Whatever you choose, remember to pair your camera with lenses that align with your shooting style and invest time mastering the features to unlock full creative potential.

Photography is an evolving journey, and selecting equipment that inspires you is the first step.

Thank you for reading this detailed comparison. Should you have further questions or need personal recommendations tailored to your shooting preferences, feel free to reach out.

Happy shooting!