Canon 5D Mark III vs Pentax K-5 II: A Deep Dive into Classic Advanced DSLRs

In the realm of advanced DSLR cameras, the Canon EOS 5D Mark III and the Pentax K-5 II stand as two distinct yet compelling choices that have earned their reputations over the last decade. Though both cameras emerged in the early 2010s, they cater to somewhat different segments of photographers - one primarily full-frame, the other APS-C; one leaning towards the professional market, the other offering high-end features for enthusiasts and semi-pro users.

Having tested thousands of cameras over the years, I find direct comparisons like these invaluable for understanding how specification sheets translate into real-world performance, creative flexibility, and value for photographers. In this article, I'll dissect these two cameras across multiple photography genres and use cases, examine their technical strengths and limitations, and help you decide which model suits your needs best.

Let’s start with the basics - size, controls, and physicality.

Handling and Ergonomics: Size Matters, But Comfort Matters More

Right off the bat, the Canon 5D Mark III impresses with its robust, mid-size DSLR body measuring 152 × 116 × 76 mm and weighing around 950 grams. The Pentax K-5 II sits a notch smaller and lighter at 131 × 97 × 73 mm and 760 grams. This size and weight difference may seem minor on paper, but it tells a story about the cameras’ design priorities.

The 5D Mark III’s heft lends it a reassuring sturdiness in hand, especially when paired with large, professional-grade EF lenses. The deep grip and solid button layout make one-handed operations more tenable during long shooting sessions. Its magnesium alloy chassis with thorough environmental sealing ensures durability against dust and moisture - critical in rugged conditions.

By contrast, the Pentax K-5 II, though smaller, maintains admirable weather resistance - Pentax is known for making tough bodies even in the APS-C market. The K-5 II's lighter weight aids portability, a boon for street and travel photographers who prefer discretion and reduced fatigue over all-day shoots. However, the grip feels somewhat less substantial for users with large hands or heavy lenses, and some controls can be smaller or more cramped.

Looking at control layouts side-by-side …

…the Canon 5D Mark III offers an intricate network of buttons, dials, and switches with an emphasis on quick, intuitive access for professionals. Noteworthy is the larger top LCD for instant status checks and multiple customizable function buttons. The Pentax K-5 II retains some shortcut buttons but leans on a simpler layout with fewer physical controls. This makes it easier for newcomers but slows rapid adjustments during fast-paced shoots.

In sum, if you prioritize a refined ergonomic experience with a proven professional layout, the Canon feels like the more natural choice. Those seeking solid weatherproofing and lighter portability without sacrificing mid-level control will find the Pentax body attractive.

Sensor and Image Quality: Full-Frame vs APS-C - The Core Differentiator

This image clearly demonstrates the most fundamental technical difference: the Canon 5D Mark III's full-frame 36x24 mm CMOS sensor dwarfs the Pentax’s APS-C 23.7x15.7 mm chip. Larger sensor area translates to superior depth of field control, dynamic range, and high-ISO performance, all else being equal.

At 22 megapixels, the Canon delivers a 5760×3840 resolution output capable of detailed large prints and extensive cropping flexibility. The Pentax runs a 16-megapixel sensor at 4928×3264 resolution, still respectable but less dense and smaller in area, equating to the classic 1.5x crop factor. This crop effectively multiplies lens focal lengths, which has pros and cons depending on shooting style.

Color Depth and Dynamic Range

DxO Mark scores confirm the Canon’s edge: a 24-bit color depth versus 23.8 for Pentax isn’t a huge margin but reflects the fine-tuned Canon color processing pipeline. Where the gap widens is dynamic range: the Pentax boasts a remarkable 14.1 stops, outperforming the Canon's 11.7 stops. This means the K-5 II excels at scenes with extreme lighting contrasts, such as harsh landscapes or high-contrast interiors, retaining more shadow and highlight nuance without resorting to HDR.

Low-Light Performance

Canon’s sensor yields a better low-light ISO score at 2293 compared to Pentax’s 1235, despite a higher maximum native ISO rating for Canon (25600 vs 12800). In practice, this translates to the 5D Mark III producing cleaner images at higher sensitivities, critically important for event and action shooters working under tricky lighting.

Anti-Aliasing and Sharpness

Both cameras retain anti-aliasing filters to avoid moiré patterns at certain frequencies. The impact on absolute sharpness is modest but noticeable when pixel peeping.

In brief, for photographers whose work demands large prints, shallow depth of field, or superior high-ISO clarity, the Canon’s sensor is a better foundation. Those valuing dynamic range for landscapes and willing to work within APS-C framing constraints will find the Pentax sensor compelling.

LCD Screen and Viewfinder: Visual Composition and Feedback

The Canon 5D Mark III sports a 3.2-inch Clear View II TFT LCD with 1,040,000 dots, providing vibrant, detailed image review and menu navigation. The Pentax K-5 II, at 3 inches and 921,000 dots, is slightly smaller and less detailed, but still solid and bright enough for outdoors use. Neither screen is touch-enabled - a reflection of their generation.

The bigger Canon screen makes a difference in reviewing critical focus areas and exposure on location, while Pentax’s screen limits magnified detail assessment, sometimes requiring image transfers back to desktop for fine evaluation.

Through the viewfinder, both models offer optical pentaprisms with 100% coverage, a professional feature ensuring you see exactly what will be captured. The Canon’s viewfinder magnification at 0.71x is noticeably larger and brighter than Pentax’s 0.61x, enhancing manual focus precision and composition ease in dim conditions.

Autofocus and Shooting Speed: Precision and Agility in Action

Autofocus performance can make or break a camera’s usability for moving subjects, be it wildlife or fast sports.

The Canon 5D Mark III boasts 61 focus points, with 41 cross-type sensors. This dense and sophisticated AF array supports accurate subject tracking, including eye detection and extensive AF area selections, critical for portrait and event photographers requiring nuanced focus control. Canon also supports face detection and continuous AF in live view but no animal eye AF - common limitations in 2012-era DSLRs.

Pentax’s K-5 II uses an 11-point system with 9 cross-type points, respectable but less dense and capable for demanding tracking tasks. It includes face detection and continuous AF for live view, yet its AF performance lags behind Canon in speed and reliability in low light.

Burst Rates

The Pentax edges ahead slightly on burst speed with 7 frames per second, versus Canon’s 6 fps. While the difference is marginal, Pentax’s advantage can matter for wildlife or sports shooters timing decisive moments.

However, Canon’s larger buffer and faster card handling help maintain longer bursts without slowdown, an advantage in sustained shooting scenarios.

Lens Ecosystem and Compatibility: Glass Matters as Much as Body

The Canon 5D Mark III uses the EF lens mount with over 250 compatible lenses spanning ultra-wide to super-telephoto, from primes through pro-grade zooms and specialty optics. This well-established and mature ecosystem offers unparalleled choice and optical quality, critical for professionals who may specialize or need specific focal ranges.

The Pentax K-5 II’s KAF2 mount supports 151 lenses, a rich but smaller ecosystem. Notably, the APS-C sensor crop factor affects field of view equivalency, making wide-angle lenses effectively less wide but telephotos more reachy. Pentax also boasts unique lenses with weatherproof build matching the camera’s ruggedness, an appealing package for landscape and field shooters.

For users invested already in either brand’s lenses, staying within that ecosystem reduces cost and friction. For newcomers, Canon clearly offers a broader and more professional lens selection.

Build Quality and Weather Resistance: Ready for the Field?

Both DSLRs feature robust magnesium alloy construction with dust and moisture sealing, yet Canon’s 5D Mark III stands at a higher tier with professional-grade sealing suitable for adverse environments. The Pentax K-5 II is impressively tough for an APS-C DSLR, ideal for outdoor enthusiasts, especially given its lighter weight and lower cost point.

Neither camera is shockproof, crushproof, or freezeproof out of the box, meaning care is needed in extreme conditions.

Video Capabilities: Not Just Still Cameras

While neither camera targets videographers in 2024 standards, they both offer full HD recording.

Canon’s 5D Mark III shoots 1080p up to 29.97 fps, using H.264 codec, a relatively efficient compression with broad editing pipeline compatibility. It includes microphone and headphone ports for audio monitoring, essential for smaller video productions.

The Pentax K-5 II records 1080p at 25 fps (PAL standard) using Motion JPEG - a less efficient codec producing larger files and more limited flexibility in editing. It includes a microphone input but lacks headphone monitoring.

In practice, such video capabilities serve occasional B-roll or video stills but fall short of professional video work without external recorders or upgrades.

Battery Life and Storage: Sustained Operation in the Field

The Canon’s LP-E6 battery rates for approximately 950 shots per charge, a figure confirmed in field tests. Dual card slots supporting fast Compact Flash and SD cards offer flexibility, simultaneous backup, or overflow shooting - a standard feature in professional DSLRs.

Pentax’s D-LI90 battery surprisingly outlasts Canon on nominal specifications with 980 shots per charge, indicating efficient power management. However, it has only a single SD slot and uses slower SD card formats, possibly limiting long-term shooting endurance.

Wireless and Connectivity: Staying Modern in a Wired World

The Canon 5D Mark III’s wireless features are optional with add-on accessories - no built-in Wi-Fi or Bluetooth. It offers USB 2.0 and full-size HDMI outputs.

The Pentax K-5 II lacks wireless connectivity altogether - no Wi-Fi, Bluetooth or NFC. USB 2.0 and HDMI ports enable basic tethering and external monitor use.

For photographers who value instant image sharing or remote control, both models show their age here; external solutions or newer cameras might serve better.

Price-to-Performance: Investment and Return

At launch prices and present resale values, the Canon 5D Mark III commands a substantial premium - approximately $2,780 new - reflecting its full-frame status and professional-grade features.

The Pentax K-5 II, at around $830 new, offers a compelling entry into weather-sealed DSLRs with respectable image quality for much less money. Its APS-C sensor constrains some possibilities but opens up affordability.

Real-World Photography Applications: Who Should Choose Which?

Canon 5D MIII front Canon 5D MIII screen back Pentax K 5 II front Pentax K 5 II screen back

With all the specs on the table, let’s look at how these cameras perform across specific photography disciplines:

Portrait Photography

Canon’s 5D Mark III excels here due to its full-frame sensor and 61-point AF system with face and eye detection. Producing pleasing skin tones, the camera offers superior bokeh thanks to larger sensors and professional lenses. Pentax’s 16 MP APS-C sensor and simpler AF array can produce decent portraits but with less creamy background separation and lower resolution detail.

Landscape Photography

The Pentax K-5 II shines with excellent dynamic range (14.1 stops) useful for challenging lighting conditions in landscapes. Its solid weather sealing lets you shoot confidently outdoors. Canon offers higher resolution and cleaner high ISO for twilight landscapes but with less dynamic range. Both cameras have robust RAW support for post-processing.

Wildlife Photography

Canon’s extensive lens ecosystem with professional telephotos and responsive 61-point AF array favors wildlife shooters needing fast, accurate tracking. Burst mode pacing and large buffer ensure minimal shot loss. Pentax’s 7 fps is quick, but limited lens selections at long focal lengths and smaller AF coverage restrict performance.

Sports Photography

Close contest, but Canon’s superior AF tracking and face detection give it an edge in capturing fast-moving athletes under various light conditions. Pentax can keep pace but falls short on autofocus sophistication.

Street Photography

Pentax’s smaller size, lighter weight, excellent dynamic range, effective stabilization, and weather sealing make it ideal for discrete street photography, especially in urban environments. Canon’s 5D Mark III, though heavier, offers better image quality where ultimate detail is required, but the setup can be more conspicuous.

Macro Photography

Canon’s larger sensor combined with suitable macro EF lenses delivers detailed, creamy images with sharper focus control. Pentax offers sensor-based stabilization, a boon for handheld macro shots, but lower resolution hampers fine detail capture.

Night / Astrophotography

Canon’s higher maximum ISO and cleaner noise profile beyond ISO 3200, combined with longer exposures and remote cable release, allow superior night sky imaging. Pentax’s lower noise floor helps shadows but is limited by sensor size and ISO ceiling.

Video Capabilities

Canon’s H.264 codec, 1080p options, and audio monitoring ports make it somewhat viable for prosumer video, whereas Pentax’s Motion JPEG and limited fps options restrict use largely to casual video.

Travel Photography

Pentax’s compactness and longer battery life suit travel photographers favoring portability and weather resistance. Canon’s professional-quality images excel when ultimate quality trumps weight concerns.

Professional Use and Workflow

Canon’s full-frame sensor, dual card slots, and extensive software support integrate seamlessly into professional workflows, including Adobe RGB color space and DNG/raw formats. Pentax lags here but offers viable RAW processing options for enthusiasts.

Overall Performance Scores: Putting It Into Perspective

The Canon 5D Mark III generally leads in overall foundational performance metrics like resolution, low light ISO handling, and autofocus capability. The Pentax K-5 II holds a strong position in dynamic range and burst speed, punching above its price class for APS-C cameras.

Genre-Specific Scoring: Who Excels Where?

Breaking it down further:

• Portraits: Canon dominant
• Landscapes: Pentax excels in DR, Canon in detail
• Wildlife/Sports: Canon leads in AF/tracking
• Street: Pentax favored for portability
• Macro: Canon for image quality; Pentax for stabilization
• Night/Astro: Canon preferred for high ISO and exposure options
• Video: Canon modest advantage
• Travel: Pentax for size and battery
• Professional use: Canon hands down

Final Thoughts: Matching Strengths to Your Vision

Both the Canon 5D Mark III and Pentax K-5 II retain relevance today despite their age, thanks to solid engineering and platform maturity.

• Canon EOS 5D Mark III - a professional full-frame stalwart delivering excellent image quality, rugged handling, sophisticated autofocus, and robust video tools. The price premium reflects a serious tool aimed at wedding, portrait, commercial, wildlife, and sports photographers seeking tried-and-tested performance.

• Pentax K-5 II - a versatile, weather-sealed APS-C camera punching above expectations for landscapes, street, and budget-minded enthusiasts requiring solid image quality and portability. Its superb dynamic range and sensor stabilization make it uniquely suited to outdoor and travel use.

If your priority focuses on high-resolution portraits, demanding action photography, or professional workflow integration, the Canon stands out as the wise investment. If budget, portability, and strong landscape or street photography are your goals, Pentax offers exceptional value and durability.

In closing, the "better" camera truly depends on what you shoot, how you shoot, and where you shoot. Having used both extensively in the field, I appreciate that these cameras embody thoughtful compromises - each a dog in its own right, earning top marks in different arenas. Choose the one that aligns closest with your creative ambitions, budget, and handling preferences, and you’re sure to find a loyal photographic companion.