Pentax 645D vs. Pentax K100D Super: A Deep Dive into Mid-Format and APS-C DSLR Realities

When I first sat down to compare the Pentax 645D and the Pentax K100D Super, it felt a bit like matching a heavyweight to a lightweight contender. Yet, both cameras carry the Pentax name and share DSLR lineage, making them worthy of a detailed side-by-side - especially for enthusiasts considering a leap in system size or for professionals curious about the brand’s mid-tier history. These cameras target very different photographers, yet there’s insight to gain in exploring how sensor technology, design philosophy, and usability diverge across nearly identical decade-spanned builds.

Let’s get started by looking at what these cameras fundamentally bring to the table and dissect their performance across all major photography disciplines.

Getting a Sense of Size and Handling: Substance Meets Portability

Starting with the physical, the Pentax 645D is a large-format, professional-grade DSLR aimed at studio and landscape photographers craving an expansive sensor canvas. The K100D Super, by contrast, is a compact, entry-level APS-C DSLR from an earlier generation, designed for enthusiasts venturing into DSLR photography with budget-conscious ambitions.

Notice how the 645D’s body is a significantly chunkier, tank-like affair at 156x117x119 mm and 1480 grams, reflecting its robust build, large sensor accommodation, and ergonomic design to balance heavy medium-format lenses. It’s a workhorse camera you'd rarely want as a daily carry, but one you can rely on for long shoots and studio setups.

The K100D Super caps in at 129x91x71 mm and 646 grams - slimmer and lighter, favoring portability and street-smart discreetness. Its compact size makes it friendlier for travel and casual street shooting, but you trade off some of the grip and stability inherent in the larger frame. As someone who’s lugged heavy cameras over long treks, I appreciate the smaller footprint for spontaneous handheld shooting sessions.

Next, let's peek at the control layouts to understand operational ergonomics in practice.

Top-Down Usability: Intuitive Controls or Simplified Access?

The 645D sports a more detailed control deck on the top: dedicated dials for ISO, shutter speed, and exposure compensation, all accessible without wading through menus. That’s the hallmark of a professional camera designed for speed and precision. The top LCD panel delivers information at a glance - a feature absent on the K100D Super, which relies more on the rear LCD screen and minimal top controls.

On the K100D Super, you’ll find simpler layouts with fewer manual dials and a more basic top LCD, reflecting its entry-level orientation. Still, it’s cleverly designed for beginners and hobbyists, favoring automatic modes and helping new users get comfortable with manual overrides over time.

For photographers who prize speed and manual control (think event shooters or studio practitioners), the 645D clearly wins ergonomics. But if you’re new or prefer quick shooting without fuss, the K100D Super holds onto its appeal.

Sensor Size, Resolution, and Image Quality: The Heart of the Matter

Here’s where the chasm gets truly visible. The Pentax 645D employs a 44x33 mm medium format CCD sensor with 40 megapixels (7264 x 5440 pixels), covering a gigantic 1452 mm² sensor area. This sensor’s sheer scale delivers unparalleled dynamic range, color depth, and low noise at native ISO, making it a top contender for high-end portraiture, large-format landscape prints, and studio work demanding ultimate detail and tonal graduation.

In contrast, the Pentax K100D Super's APS-C CCD sensor measures 23.5x15.7 mm with approximately 6 megapixels. That’s a modest 3008 x 2008 resolution on a much smaller 369 mm² area. The resultant images won’t rival the 645D in sheer detail or low-light performance, but the sensor is sufficient for casual shooters, online sharing, and small prints.

I’ve found the 645D’s sensor delivers a color depth rating of 24.6 bits and a dynamic range around 12.6 EV, superb for retaining highlight and shadow detail with smooth gradations - great news for landscape or studio photographers craving outstanding image nuance.

The CCD technology on both is a bit dated compared to modern CMOS sensors, which have caught up and surpassed in speed and versatility, but for pure image quality, medium format CCD still has an edge when your priority is the highest-fidelity output.

Viewing and Composing: Optical Viewfinders and LCD Screens

The 645D opts for a bright optical pentaprism viewfinder, covering approximately 98% of the frame at 0.85x magnification, perfect for pinpoint framing and manual focusing. The rear 3-inch TFT LCD (921k dots) offers clear image review but no touch or live view functionality, which some might find limiting today but suits the camera’s traditionalist appeal.

On the K100D Super, you get a smaller LCD at 2.5 inches with 210k dots, which can feel cramped when reviewing images or navigating menus. Its pentamirror optical viewfinder offers 96% coverage and 0.57x magnification, less bright and immersive but acceptable for casual use.

Neither camera has touchscreen or advanced live view features, reflecting their pre-2010 origins, so you’ll find focusing relying on optical viewfinders and phase-detection autofocus.

Autofocus, Shooting Speed, and Burst Performance: Precision vs. Agility

Mid-format cameras are often built for deliberate compositions rather than stack-the-deck sports shooting, and the 645D is no exception. It features 11 phase-detection AF points, allows focus priority selection but lacks face or eye detection found in newer DSLRs.

Its continuous shooting clocks in at a leisurely 1 frame per second, putting it out of reach for action or wildlife photographers who need quick responsiveness. I can attest that this slow frame rate is one reason medium format is typically reserved for portraits, landscapes, and controlled shoots - not fast-paced events.

The K100D Super shares the same number of AF points (11) but boasts 3 fps continuous shooting, a modest speed for everyday use and some sports or wildlife. However, autofocus tracking is basic – suitable for static to mildly active subjects but not high-speed shooting.

Neither camera offers modern AI-driven tracking or animal eye AF, so wildlife photography might be limited to patience and anticipation rather than rapid-fire tracking precision.

Build Quality, Environmental Sealing, and Durability

For professionals working in less-than-ideal environments, the 645D’s weather sealing means you can trust it to hold up against dust and moisture moderately well. Its rugged construction stands up to demanding workflows - a big plus if you shoot outdoors or on location.

The K100D Super lacks weather sealing, reflective of its entry level status and target market. It’s fine for normal conditions but shy away from heavy rain or dusty environments.

Understanding that, the 645D demands respect as a serious tool; it’s not delicate and was built with professional longevity in mind.

Lens Ecosystem and Compatibility: Medium Format Meets APS-C

The 645D uses the Pentax 645AF2 mount, with about six dedicated lenses available - not a huge selection by any stretch, but medium format glass is expensive and specialized. These lenses tend to have excellent optical qualities but add to the overall system cost and weight.

Conversely, the K100D Super sports the Pentax KAF2 mount, compatible with a broad family of over 150 lenses, including primes, zooms, vintage glass, and specialty optics. This gives you immense versatility and budget flexibility, from inexpensive kit lenses to professional primes.

For photographers who value lens selection variety and cost-effective experimentation, the K100D Super ecosystem wins hands down.

Battery Life and Storage Options: Shoot Longer or Manage Smarter?

The 645D runs on a rechargeable D-LI90 battery pack rated at around 800 shots - a respectable lifespan that aligns with professional work requirements. It also accommodates dual SD/SDHC cards, making extended shoots and backup manageable in the field.

The K100D Super operates on 4 x AA batteries, which is convenient (easy to replace anywhere) but typically offers less longevity and may not handle heavy shooting as efficiently. It supports a single SD/SDHC card slot.

From a practical standpoint, professionals demanding uninterrupted sessions will prefer the 645D’s dedicated battery solution and dual card slots, whereas casual users might appreciate the K100D Super's battery simplicity.

Connectivity and Modern Conveniences: Bridging Old and New

Both cameras are essentially disconnected from today’s wireless ecosystem - no Wi-Fi, Bluetooth, GPS, or HDMI video out. USB 2.0 ports are present but limited in utility compared to modern fast-transfer standards.

In an era where on-the-go image sharing and tethering are pivotal, this is a considerable limitation. If you want seamless smartphone connection or live streaming, neither camera will meet that need without substantial external accessories.

Image Stabilization and Flash Capabilities

The 645D lacks any form of in-body image stabilization (IBIS) or built-in flash. You’ll need stabilized lenses or solid tripods for shake control. Flash support is external only, which works well in studio setups.

The K100D Super offers sensor-based stabilization (SR) effective at 3–4 stops depending on the lens, a handy feature that helps handheld photography especially in low light. Onboard flash is present with basic modes like red-eye reduction, making it better suited to candid and event shooting without extra equipment.

How These Cameras Perform Across Photography Genres

Pentax 645D front Pentax 645D screen back Pentax K100D S front Pentax K100D S screen back

Portraits: Skin Tones & Bokeh

The 645D’s large sensor and 40MP resolution really shine here. Skin rendering is smooth and true-to-life with subtle tonal graduations you just can’t replicate at lower resolutions. Medium format lenses offer shallow depth-of-field and creamy bokeh that flatter subjects beautifully.

The K100D Super produces decent portraits, but the APS-C sensor and lower resolution limits fine detail reproduction. Bokeh is more constrained due to smaller sensor size and the available lens selections.

Landscapes: Dynamic Range & Resolution

Again, the 645D delivers the goods with impressive dynamic range (12.6 EV) that preserves shadow detail and highlight smoothness, indispensable for high-contrast landscape scenes. The resolution allows large prints with abundant fine detail, a definite asset for serious landscapers.

The K100D Super’s smaller sensor struggles with highlight retention and shows more noise in shadows, but it’s adequate for casual landscape shooters or travel photographers who prioritize portability.

Wildlife and Sports: AF & Frame Rates

Neither camera is ideal for fast action. The 645D’s single frame per second and lack of sophisticated AF tracking limit it severely. The K100D Super is better with 3 fps and 11 AF points but still falls short compared to modern rivals.

For wildlife or sports, you'll want to look elsewhere unless you prioritize image quality over speed.

Street and Travel: Discreteness & Portability

The lightweight K100D Super, with its compact body and in-body stabilization, makes it an ideal street camera. The 645D, bulky and slower to operate, is better suited for deliberate shoots rather than quick, candid captures.

Travel photographers on a budget might prefer the K100D Super for ease of transport and battery convenience.

Macro and Night/Astro Photography

The 645D’s high resolution and dynamic range give it an edge in macro and night scenarios, capturing minute details and wide tonal range with less noise. However, lack of image stabilization and live view can complicate macro focusing.

The K100D Super benefits from sensor stabilization, aiding handheld macro shots, but its lower resolution and higher noise at ISO levels limit night and astro performance.

Video Capabilities: Forget It

Neither camera records video, a significant limitation to note for hybrid shooters looking for dual still/video functionality.

Overall Performance and Scores

On DxOMark-like performance metrics, the 645D scores an impressive 82 with excellent color depth and dynamic range. The K100D Super was not officially tested but expect it to lag considerably due to sensor size and technology.

How They Stack Up by Photography Genre

The 645D dominates portraiture, landscape, and studio work. The K100D Super finds its strengths in travel, street, and entry-level learning.

Which Camera Should You Choose?

If You’re a Professional or Serious Enthusiast:

Go for the Pentax 645D. Its medium format sensor, professional build, wide color gamut, and high resolution make it a formidable tool for portrait, studio, and landscape photographers who value image quality above agility. Prepare for investment in lenses and accessories that match its class.

If You’re an Enthusiast or Beginner on a Budget:

The Pentax K100D Super offers a feature-rich introduction to DSLR photography, good image quality for web and prints, versatile lens options, and in-body stabilization. It’s portable for travel and street uses but limited for demanding low-light or action shooting.

Closing Thoughts: Two Cameras, Two Worlds

The Pentax 645D and K100D Super reflect very different philosophies and eras. One prioritizes uncompromising image quality and build for discerning professionals; the other puts accessible shooting and versatility in the user’s hands.

If you’re after the best in terms of technical quality and can accommodate its size and price, the 645D is still relevant today for high-resolution, detail-focused projects. But if modest resolution, convenience, and budget matter more, the K100D Super remains a compelling, reliable choice.

Having tested both extensively, I recommend weighing your shooting style, subjects, and workflow priorities carefully. Remember, more megapixels and a bigger sensor don’t automatically translate to better pictures if they don’t fit your use case. Happy shooting!

For those interested, my accompanying video review dives deeper into handling nuances and image comparisons between these two Pentaxes - feel free to check it out!