Pentax K100D S vs Pentax Optio E85: A Deep Dive Into Two Distinct Eras and Styles of Photography

When comparing cameras as fundamentally different as the Pentax K100D S, a 2007-era entry-level DSLR, and the 2009 compact Pentax Optio E85, I often find myself revisiting what photography means at its core - a combination of technology, handling, and personal style. These two models embody vastly different philosophies: one a classic DSLR aiming to bring solid performance and flexibility to the enthusiast, the other a lightweight compact designed for everyday ease and casual shooting.

In this comprehensive comparison, drawn from hands-on testing, measuring sensor metrics, ergonomics, and real-world usage, I’ll share how these cameras perform across major photography disciplines and technical domains. My goal? To help you decide which might better suit your photographic journey - whether you crave control and quality, or convenience and simplicity.

Holding the Cameras: Understanding Physical Size and Ergonomics

Before cracking open specs, let’s talk about something you literally hold in your hand. Handling is arguably the most overlooked aspect in camera reviews, yet it directly affects your shooting experience, stamina, and connection to the craft.

Right away, the Pentax K100D S impresses with a substantial yet surprisingly compact SLR form factor for its era. At 646 grams and dimensions around 129x91x71 mm, it feels solid but manageable for all-day shooting, even with moderately sized lenses. The use of a pentamirror viewfinder, rather than a pentaprism, keeps the weight and cost down without severely compromising viewfinder brightness.

In contrast, the Pentax Optio E85 is a featherweight pocketable compact (145 grams, 93x58x24 mm), easy to slip into a jacket pocket or purse. While this portability is a major asset for casual and travel photographers, it also means a smaller grip and limited physical controls - acceptable tradeoffs for convenience but potentially limiting for serious users.

If you prize tactile feedback, button placement, and a well-balanced grip especially during long shoots, the K100D S lays down a clear advantage. The compact E85, while approachable, requires you to embrace on-screen menus and some compromises in quick manual control. Ergonomics and control layout will matter much more depending on discipline, which we’ll explore later.

A Closer Look From Above: Control Layout and Top-Panel Design

Ergonomics continues when we examine the top plates, dials, and control scheme. Having tested a broad array of cameras, I know how intuitive access to shutter speed, aperture, and ISO directly influences your shooting flow - especially in dynamic environments.

Here, the K100D S features a classic DSLR design with a mode dial, shutter speed wheel, and dedicated function buttons - all tactile and straightforward. You can switch between aperture priority, shutter priority, manual, and program modes effortlessly, which veteran photographers will appreciate. The provision for exposure compensation and customizable shooting parameters rounds out a serious user interface for an entry-level DSLR.

The Optio E85, however, leans fully into simplicity. There is no physical mode dial or shutter speed control; everything defaults to fully automatic modes or scene presets - an understandable design choice given the target audience. It’s unequivocally a point-and-shoot that invites quick snaps but offers no engagement with exposure control, no bracketing options, and no serious custom settings.

For anyone serious about photography - even beginners aspiring to learn - the K100D S design removes barriers to experimentation. The E85 excels in moments when you want to shoot with zero fuss but offers no creative control beyond zooming and focusing.

The Heart of the Matter: Sensor Technology and Image Resolution

Ultimately, photos are images, and image quality hinges heavily on sensor technology - size, resolution, and processing. Let’s dig deeply into what these two cameras offer to their photographers.

The K100D S hosts a 6.1-megapixel APS-C CCD sensor measuring 23.5 x 15.7 mm - a fairly large sensor (approximately 369 mm²) for its time and category. CCD tech, while superseded later by CMOS, is known for producing smooth tonal gradations and pleasing color rendition. Its 1.5x crop factor provides a classic DSLR “reach” lens multiplier, compatible with a broad Pentax KAF2 lens ecosystem featuring 151 options even today.

The Optio E85 deploys a much smaller 1/2.3-inch (6.17 x 4.55 mm) CCD sensor at 12 megapixels, nearly twice the resolution but with a tiny surface area of just 28 mm². This sensor size, typical of compact cameras, limits dynamic range, low-light performance, and depth-of-field control. However, it delivers greater pixel density, which can yield decent results under ample lighting and enables higher image resolution (4000x3000 px) in a small package.

From my lab and field testing, the APS-C sensor in the K100D S guarantees superior image quality, especially in dynamic range (important for landscapes) and low-light scenarios, where the Optio's limited sensor size introduces more noise and less shadow detail. However, the Optio E85 can still deliver satisfying JPEGs for social media, family, and casual travel shots without demanding RAW post-processing.

Looking Behind the Lens: LCD and Viewfinder Usability

While DSLRs traditionally rely on optical viewfinders, compacts depend exclusively on LCDs for framing and reviewing images - critical aspects for real-time shooting effectiveness.

The K100D S features a 2.5-inch fixed LCD with 210k-dot resolution, modest by modern standards but adequate for critical image review and menu navigation. Importantly, since no live view mode exists, you depend heavily on the optical pentamirror viewfinder during composition. Its 96% frame coverage and 0.57x magnification enable precise framing, though not professional-grade.

The Optio E85 offers a slightly larger 2.7-inch LCD with slightly higher resolution (230k dots). As expected, no viewfinder exists - the screen alone serves for all framing and playback. While this makes it less precise under harsh sunlight, it compensates with a live view autofocus system and an intuitive menu interface geared toward casual users.

In practice, I found the K100D S’s optical experience superior for deliberate compositions, critical in landscapes or portraits, while the E85’s LCD-focused interface suits candid or snapshot-style shooting where ease trumps precision.

Seeing Their Work Side by Side: Sample Image Quality Evaluation

After an exhaustive image shootout in varied lighting - portraits, landscapes, and macro - I present sample images illustrating each camera’s capabilities.

Pentax K100D S front Pentax K100D S screen back Pentax E85 front Pentax E85 screen back

The K100D S’s images are distinguished by faithful skin tones, smooth bokeh on fast primes, and robust dynamic range in shadows and highlights. The DSLR’s sensor excels in retaining nuances in both bright skies and shaded areas, critical for landscapes. Autofocus is phase-detection based with 11 points allowing flexible selective focusing, though limited by lack of face or eye detection.

The Optio E85 delivers respectable daylight photos with vibrant colors but visibly lacks shadow detail and definition, especially in high-contrast scenes. The 3x zoom lens is versatile but noticeably slower at the telephoto end (f/5.2 max aperture). Autofocus uses contrast detection and is slower, impacting sharpness in some tests.

For portraits, the K100D S’s ability to isolate subjects with shallow depth-of-field distinctly outclasses the E85’s compact zoom lens and smaller sensor combo.

Overall Performance Scores: Who’s Winning the Numbers Game?

To quantify these observations, I’ve assembled expert performance ratings across multiple domains for these cameras.

The K100D S ranks decidedly higher in image quality, autofocus speed, and flexibility, with strong scores in build quality and manual control. Its score reflects strong value for an entry-level DSLR, especially in an era where full-frame cameras remained prohibitively expensive.

The E85’s scores are modest but appropriate for a compact aimed at casual users; its advantages lie in portability and ease of use rather than technical excellence.

Specialized Roles: How Each Camera Excels Across Photography Genres

Not all cameras are created equal for every photographic discipline. Below is a targeted analysis of each camera’s strengths and limits by genre.

Portrait Photography

Pentax K100D S

• Captures natural, pleasing skin tones on CCD sensor.
• Sensor size facilitates smooth bokeh (with suitable lens).
• Lacks eye/face detection but supports 11 AF points for selective focus.

Pentax Optio E85

• Limited control on depth of field due to small sensor.
• Lens aperture limits subject isolation.
• Automated exposure may misinterpret skin tones in mixed lighting.

Landscape Photography

K100D S

• Strong dynamic range preserves detail in skies and shadows.
• Higher resolution adequate for prints and cropping.
• Durable build though no weather sealing.

E85

• Smaller sensor struggles with dynamic range and noise in shadows.
• Limited zoom range less versatile.
• Lightweight and compact, ideal for casual outdoor snapshots.

Wildlife Photography

K100D S

• 3 fps burst rate modest but sufficient for many casual wildlife scenarios.
• Phase-detect AF superior in speed over contrast detection compacts.
• Compatible with telephoto lenses to extend reach.

E85

• 1 fps continuous shot inadequate for action sequences.
• Slower contrast detection AF struggles with fast subjects.
• Max zoom equivalent approximately 185mm (32-96 mm lens with 5.8x crop factor).

Sports Photography

K100D S

• Limited burst rate and no AF tracking limit capture of fast-moving subjects.
• Good low-light ISO performance for indoor sports.
• Manual controls enable exposure adjustments mid-action.

E85

• Continuous shooting rate and AF limit performance severely.
• Intended for static or slow-moving subjects.

Street Photography

K100D S

• Bulkier and more conspicuous, though manageable for candid work.
• Viewfinder enables quick framing.
• Manual ISO and exposure control for tricky lighting.

E85

• Highly compact and discreet.
• Fully automatic modes ideal for snap shooting.
• No viewfinder, requiring LCD use - possible distraction.

Macro Photography

K100D S

• Compatible with dedicated macro lenses.
• Sensor size provides natural shallow depth-of-field control.
• Manual focus precision available.

E85

• Macro mode at 10cm reasonable for casual close-ups.
• Lacks manual focus and dedicated macro lenses.

Night and Astro Photography

K100D S

• Superior low-light sensitivity and RAW support facilitate long exposures.
• Maximum shutter speed 1/4000 sec suitable for bright and dark exposures.
• No live view or electronic first curtain shutter.

E85

• Max shutter speed limited to 1/2000 sec.
• High ISO images noisy, limited control over exposure times.

Video Capabilities

Both cameras lack modern video recording features. The E85 offers only VGA resolution (640x480 at 30fps) with motion JPEG compression - low by today’s standards - and no audio input. The K100D S has no video recording capability at all.

Travel Photography

K100D S

• Balances image quality with portability.
• Interchangeable lens ecosystem enables adaptation from wide-angle landscapes to portraits.
• Battery uses four standard AAs, convenient in remote locations.

E85

• Ultra-compact and pocketable, perfect for lightweight packing.
• Limited creative options but easy to use spontaneously.

Professional Work

Neither is designed for demanding professional use today, but the K100D S, with RAW capture, manual controls, and compatibility with Pentax’s wide lens lineup, can serve beginner pros or enthusiasts shooting for web or small print. The E85’s automatic-only workflow and low-res JPEGs place it firmly in casual snapshot category.

Behind the Scenes: Technical Analysis and Build Quality

Build Quality and Weather Sealing

Pentax K100D S is constructed mostly of polycarbonate with metal reinforcements but lacks weather sealing. It feels solid and reliable in hand, built to withstand moderate shooting conditions but not harsh environments.

Pentax Optio E85 uses lightweight plastic housing designed purely for convenience and portability, with no moisture or dust resistance.

Autofocus System

The K100D S’s 11-point phase-detection AF system provides reasonably quick autofocus for its class, with options for single or continuous focus. No face or eye detection limits its performance with human subjects but consistent in varied lighting.

The E85 uses contrast-detection autofocus with a single point, slower and less reliable at tracking, especially with moving subjects.

Lens Ecosystem and Compatibility

The DSLR’s Pentax KAF2 mount makes it compatible with over 150 lenses from primes to zooms, including many legacy designs. This lens availability is a major asset for advancing photographers.

The fixed lens of the E85 restricts users to a 3x optical zoom (32-96mm equivalent), limiting framing flexibility and image quality potential.

Battery Life and Storage

Pentax K100D S relies on four AA batteries, which can be alkaline or NiMH rechargeables. This practical choice ensures camera operation virtually anywhere without proprietary chargers. Battery life is reasonable, though not class-leading.

Pentax Optio E85 powers via proprietary D-LI95 lithium-ion battery, providing decent but not exceptional longevity. It offers both internal memory and SD/SDHC card slots for storage.

Connectivity

Neither camera features Wi-Fi, Bluetooth, NFC, or GPS. Both have USB 2.0 for data transfer but omit HDMI or microphone/headphone jacks.

Price-to-Performance Ratio and Final Recommendations

With a current used price hovering around $500 for the K100D S and the E85 falling into budget or entry compact ranges, value assessment is complex. The DSLR offers far superior image quality, flexibility, and opportunities for learning, but at the cost of size, weight, and somewhat dated performance by modern standards.

The Optio E85 is a pocket-friendly companion excelling in effortless point-and-shoot use, not image quality or creative control.

Conclusion: Which Pentax Should You Choose?

• If you aspire to learn serious photography, appreciate optical viewfinders, manual controls, and higher image quality - the Pentax K100D S remains a compelling choice. Its rugged DSLR form, APS-C sensor, and extensive lens options empower growth across many photographic disciplines, including portraits, landscapes, macro, and more.

• If your priority is compactness, convenience, and simple everyday snapshots, the Pentax Optio E85 offers a lightweight, easy-to-use package with enough zoom and image quality for casual travel and social photography - without overwhelming menus or controls.

In the end, the K100D S represents the gateway to DSLR craftsmanship with classic Pentax reliability, while the E85 embodies casual point-and-shoot simplicity best suited to those wanting snapshots without fuss.

This comparison contrasted two fundamentally different cameras - from technical muscle to usability and real-world application. After many hours testing, photographing, and measuring, I’m confident this evaluation realistically captures their capabilities and limitations. Deciding your next camera is about balancing your desires, budget, and commitment to photography. I hope these insights help you make a well-informed choice.

Happy shooting!