Pentax K-5 vs Pentax K100D: An In-Depth Comparison Across Photography Genres and Use Cases

In the ever-evolving world of digital photography, Pentax has carved out a distinctive niche with robust DSLRs that appeal to a broad spectrum of photographers - from entry-level enthusiasts to seasoned pros. Today, I dive deep into two prominent members of the Pentax lineage: the advanced mid-size Pentax K-5 from 2010, and the more modest Pentax K100D, Pentax’s 2006 entry-level DSLR.

Having tested both extensively over the years, I’ll compare them thoroughly from sensor technology to ergonomic design, covering all major photography disciplines and professional demands. Whether you’re hunting for your first DSLR or considering an upgrade path, this comprehensive review will clarify which model deserves your attention.

Holding them in your hands: Size, build, and ergonomics matter

It all starts with how a camera feels and fits - ergonomics play a crucial role in usability, especially in long shooting sessions.

The Pentax K-5 is noticeably larger but still comfortably within the realm of mid-size DSLRs. Its magnesium alloy weather-sealed body exhibits professional-grade durability and a solid grip. The Pentax K100D, by contrast, is more compact - a lightweight, “compact SLR” that fits easily into a travel bag or smaller hand.

I appreciate the K-5’s balance and heft for stability, especially in telephoto or long exposure scenarios. The K100D’s smaller body is less imposing but can feel a bit underwhelming for prolonged use or bulkier lenses. On weight, the K-5, despite its rugged design, remains manageable at 740g vs. 660g for the K100D.

In practical terms, if portability is your top priority for street, travel, or casual photography, the K100D’s smaller footprint is attractive. For demanding environments requiring weather sealing and robust handling - think landscapes or wildlife in variable weather - you’ll welcome the K-5’s build and grip.

Control layout and top-panel usability: Direct access counts

Beyond physical feel, how intuitive and responsive the controls are can markedly speed up workflow.

The K-5 incorporates a more sophisticated top control layout, including an additional info LCD and dedicated dials for quick exposure mode and ISO adjustments - features I routinely use in fieldwork to fine-tune settings without diving into menus.

The K100D’s control top is simplified, with fewer dedicated dials and more reliance on menu navigation. While functional for beginners, I often felt slowed down when chasing fast-action subjects or shifting lighting conditions.

Both models retain the classic Pentax button placements I’ve come to appreciate, but the K-5’s illuminated buttons and ergonomic dial knurls present a clear advantage for low-light and professional workflows.

Sensor prowess: Resolution, sensitivity, and image quality

Image quality is paramount, and this largely hinges on sensor technology. Here, the differences are stark and worth delving into.

The Pentax K-5 sports a 16MP APS-C CMOS sensor with an anti-aliasing filter, supported by the Prime II image processor - a major leap from the K100D’s 6MP CCD APS-C sensor. The K5’s sensor dimensions (23.7 x 15.7 mm) slightly outmatch the K100D (23.5 x 15.7 mm), but the resolution jump alone dramatically enhances detail capture and cropping flexibility.

From my side-by-side pixel-level comparisons during testing, the K-5 delivers richer color depth (DxO Color Depth of 23.7 bits versus untested on the K100D but typical for CCD chips at this resolution), superior dynamic range (14.1 EV vs. none tested), and notably better handling of noise at higher ISO.

The K100D maxes out at ISO 3200 with tonal and chroma noise becoming apparent by ISO 1600. The K-5, with a native ISO ranging from 80 to 12800 and expansions to ISO 51200, maintains cleaner images at ISO 3200 and usable results all the way up to 6400. For low-light or night shooters, this difference is a game changer.

In practical terms:

• The K-5’s sensor supports shooting demanding landscapes with rich tonal gradations and highlight recovery.
• Portrait photographers benefit from its higher resolution and color fidelity, faithfully rendering skin tones.
• Wildlife and sports shooters get cleaner results without resorting to heavy noise reduction.

The K100D remains capable for casual usage and is best deployed in good light environments where ISO can stay low.

Viewing and composing: LCD and viewfinder qualities

Composition and image review get a boost - or a bottleneck - from the viewfinder and rear screen.

The K-5’s 3-inch TFT fixed LCD boasts a sharp 921K-dot resolution, delivering crisp, vibrant playback and menu navigation. The K100D’s 2.5-inch LCD feels comparatively tiny and muted at 210K dots, which can strain reviewing delicately exposed images or confirming fine focus.

The Pentax K-5 employs a bright, high-magnification optical pentaprism viewfinder covering 100% of the frame at 0.61x magnification - superior to the K100D’s pentamirror design with 96% coverage and 0.57x magnification. This means the K-5 offers a more accurate and immersive framing experience, essential for precision composition, critical in portrait, landscape, and wildlife photography.

Autofocus systems put to the test

A camera’s autofocus (AF) system profoundly affects your ability to capture fleeting moments or achieve razor-sharp focus in challenging conditions.

The K-5 employs an 11-point phase-detection AF system with 9 cross-type sensors and supports face detection, continuous AF, and live view contrast detection. The K100D has the same number of AF points but lacks cross-type sensors and advanced tracking, face detection, or live view autofocus entirely.

Pentax K 5 front Pentax K 5 screen back Pentax K100D front Pentax K100D screen back

What I found: The K-5’s AF locks focus swiftly and accurately on moving subjects, even in low light, thanks to its sensitive cross-type points. Its ability to track and track continuously (with 7 fps burst shooting) is a boon for sports and wildlife photography - especially when paired with fast telephotos.

By contrast, the K100D’s AF is slower and prone to “hunting” in dim settings. Its 3 fps maximum burst limits action capture, making it better suited to still subjects and slower-paced photography like portraits or static landscapes.

Shutter, burst, and video capabilities

The K-5 delivers shutter speeds from 30 to 1/8000 seconds, plus a maximum flash sync of 1/180 sec. The K100D maxes out at 1/400 seconds shutter speed and the same flash sync timing.

The K-5’s 7 fps burst rate doubles the K100D’s 3 fps, enabling a far superior chance at nailing fast-moving scenes in sports or wildlife contexts.

Video recording sets the cameras further apart: The K-5 shoots Full HD 1080p at 25 fps with microphone input - suitable for integrating decent audio capture into hybrid still/video workflows. The K100D offers no video functionality at all, consistent with its 2006 entry-level design.

These differences underscore the K-5’s role as a hybrid shooter’s tool and professional backup camera, while the K100D remains firmly stills-only.

Lens compatibility and ecosystem

Both cameras utilize the Pentax K-mount system, although with slightly different variants: the K-5 features the KAF2 mount, and the K100D the KAF mount. Both are backward-compatible with a vast range of Pentax lenses - over 150 native choices exist for either.

In my experience, the K-5’s improved mechanical coupling supports newer auto-focus lenses with SDM (Supersonic Drive Motor) for quieter, faster AF. The K100D handles older screwdrive AF lenses well but can’t take advantage of the latest lens features.

This opens a wider door for creativity and specialized optics (macro, tilt-shift, ultrawide) on the K-5, enhancing its versatility across genres.

Battery life, storage, and connectivity

Battery life is another critical practical detail.

The K-5 uses a rechargeable D-LI90 pack, delivering an impressive estimated 980 shots per charge, which I confirmed in field conditions with mixed live view and burst shooting. The K100D relies on four AA batteries - a practical but less efficient solution that requires carrying spares and can deliver uneven power performance.

Storage-wise, both cameras use single SD card slots, but the K-5 supports SDHC and SDXC cards, allowing faster write speeds and higher capacities suitable for its larger files and video data. The K100D also accepts MMC cards, which are less common today.

Connectivity-wise, neither camera has wireless features, but the K-5 has an HDMI out for external monitors and a microphone port for audio - both absent on the K100D.

Toughness and weather sealing: Ready for the field?

For outdoor and adventure photographers, weather sealing and environmental resistance can make or break a camera’s reliability.

The K-5 offers comprehensive environmental sealing, making it dust and splash resistant - a critical advantage for landscape, wildlife, and travel photographers who often brave unpredictable conditions. The K100D lacks any weather sealing or ruggedization features, limiting its reliability outdoors, especially in harsh environments.

How they perform by photography genre

Now, let’s break down their real-world strengths across major photographic disciplines. I’ve paired these insights with data from DxOMark and my own controlled tests.

Portrait photography

K-5: Higher resolution sensor captures exquisite skin detail, with superior color depth reproducing natural flesh tones. Its better AF with face detection helps nail sharp eyes consistently. The body’s in-body stabilization also aids slower portrait lenses handheld. Bokeh quality benefits from pairing with fast Pentax primes.

K100D: Lower resolution and noisier high ISO limit portrait quality. AF is less forgiving for moving models or imperfect light. Still, in bright, controlled environments, it yields respectable results.

Landscape photography

K-5: Excellent dynamic range (14+ stops) and high resolution deliver stunning detail retention in shadows and highlights. Weather sealing adds security for rainy or windy landscapes. 3” high-res LCD aids meticulous composition and review.

K100D: CCD sensor offers good color rendition but limited dynamic range and resolution restrict post-processing latitude. No weather sealing is a drawback outdoors.

Wildlife photography

K-5: Fast, accurate phase-detection AF with 7 fps burst is a wildlife shooter’s dream. High ISO performance tackles dawn or dusk scenes without excessive noise. The camera’s durability and remote shooting options (with GPS add-on) make it a rugged field companion.

K100D: Slower AF and limited burst frequency constrain capturing fast animals. High ISO decline means day-light-only shooting best.

Sports photography

K-5: Superior autofocus tracking and high frame rates allow better capture of athletes in motion. Noise handling aids indoor sports conditions. Mirror lock-up and exposure bracketing aid creative experimenting.

K100D: More suited for static or slower-paced sporting events due to AF and burst limits.

Street photography

K-5: Larger size may draw more attention; however, silent shutter mode helps discretion. Low-light prowess benefits night scenes. Ergonomics permit quick changes in fast street encounters.

K100D: Smaller, lighter, and less conspicuous - great for blending into the urban environment. Simple controls favor rapid snapshots but limited ISO range hampers night street shooting.

Macro photography

K-5: Supports sensor-based image stabilization, improving handheld macro shots. Higher resolution aids capturing fine texture. Compatibility with a wider array of macro lenses helps specialized focusing needs.

K100D: Limited resolution and lack of stabilization make macro challenging but manageable with good lighting and tripod support.

Night and astrophotography

K-5: Clean high ISO output, good dynamic range, and manual exposure controls make it a competent star tracker/astro camera. The built-in intervalometer simplifies time-lapse star trails.

K100D: Higher noise at ISO above 800 discourages night shooting beyond basics.

Video capabilities

K-5: Records Full HD 1080p at 25fps with Motion JPEG compression (not the most efficient codec, but acceptable). External mic input supports serious videography. No 4K or advanced codecs, but adequate for casual to semi-pro use.

K100D: No video recording available.

Travel photography

K-5: Versatile features, solid battery life, and weather sealing make it an excellent all-in-one travel companion, despite the slightly larger size.

K100D: Compact and lightweight, easy to carry for long trips. Lacks weather removal, video, and high ISO flexibility, so suitable mainly for casual travel shots.

Professional use

K-5: Supports professional workflows with RAW support, extensive exposure modes, sturdy construction, and reliable storage options. Its extensive lens ecosystem and customizable controls are vital for demanding jobs.

K100D: Serves well as a beginner or backup option in pro suites but is limited in speed, resolution, and ruggedness.

Putting it all together: Performance ratings at a glance

Based on our comprehensive tests, covering sensor performance, autofocus speed, usability, and reliability, the K-5 consistently outperforms the K100D by wide margins. It’s a much more capable tool designed for serious enthusiasts and pros, while the K100D’s value lie in accessible entry points for new DSLR users.

Pros and Cons summary

Who should buy which?

If you’re a casual hobbyist, beginner, or on a tight budget and mostly shoot outdoors in good light, the Pentax K100D is still a respectable entry DSLR, offering a solid brand ecosystem and fundamental photographic features.

However, if you aim for professional-quality images, need robust performance in varied lighting, want to shoot video, or need a camera that can go pro in rugged conditions, the Pentax K-5 is the clear winner. It balances advanced features, image quality, and durability, providing long-term value for enthusiasts and pros alike.

Final thoughts

Drawing from thousands of hours testing both models, I’ve seen firsthand how technological leaps between these cameras affect photographic expression. The Pentax K-5 elevates everything - the sensor, autofocus, handling, and durability - to enable creativity in virtually every major photography discipline.

The K100D still has charm - compact, easy to use, and suitable for newcomers wanting an affordable introduction to DSLR photography. But the price of progress is clear: K-5’s innovations in sensor technology, autofocus, and weather sealing shape it as a more versatile and future-proof choice.

Whether you prioritize portability or performance, understanding these strengths helps align your purchase with your photographic goals.

For further detailed technical analysis or genre-specific sample galleries, feel free to reach out or explore our in-depth reviews.

Thanks for reading, and happy shooting!

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• Pentax K 5 front Pentax K 5 screen back Pentax K100D front Pentax K100D screen back