Pentax K100D vs. Pentax Optio VS20: A Hands-On Comparison for Real-World Photographers

Choosing a camera is never easy - especially when the options come from the same brand but play in very different leagues. Today, I’m diving deep into two Pentax models from different eras and segments: the Pentax K100D, an entry-level DSLR from the mid-2000s, and the Pentax Optio VS20, a compact superzoom that launched six years later for casual shooters craving reach.

Having tested thousands of cameras over my 15+ year journey as a reviewer, I’ll walk you through everything from sensor tech to ergonomics, from autofocus grunt to image quality finesse. By the end, you’ll have a clear picture of which suits your photography style and budget - not just specs on paper. And as always, I’ll be candid about limitations, so there are no cheapskate surprises.

Ready? Let’s get into the nitty-gritty.

Seeing the Bodies: Handling and Ergonomics

Before you even fire a shot, the camera’s body shapes how you feel about shooting. Size, weight, and button layout can make or break those all-important moments.

First, feast your eyes on this size comparison:

The Pentax K100D is a compact DSLR weighing around 660 grams with dimensions of 129x93x70 mm. It's a little brick - chunky but solid - as expected from a 2006 entry-level DSLR. This heft gives a reassuring grip and stability, especially with larger lenses. The camera's depth makes it comfortable for those with regular-sized hands, providing places to rest your clubs for thumbs and fingers alike without awkward stretches.

Meanwhile, the Pentax Optio VS20 is a featherweight compact at just 235 grams and measures 111x61x38 mm. It slips effortlessly into jacket pockets and demands zero commitment to handholding style. Its slim profile is perfect if portability is your absolute priority, but this comes at a cost - we’ll touch on that soon.

Look closer at their control surfaces:

The K100D boasts a traditional DSLR top deck with a mode dial offering manual, aperture priority, shutter priority, and program modes - ideal for enthusiasts wanting creative control. The dedicated buttons and dials are spaced well, helping you switch quickly without menu diving. The optical pentamirror viewfinder, while not a pro-grade finder, provides roughly 96% coverage and a magnification of 0.57x, decent for framing precision.

By contrast, the VS20 packs its controls tightly on the compact body. No mode dial here - manual exposure is out, with auto and a handful of scene presets dominating. The buttons are small but responsive. No viewfinder exists, so you’re tethered to the 3-inch rear screen for composing, which has a high 460k dot resolution and anti-reflective coating aiding visibility outdoors (more on this later).

Bottom line: If you prize grip and manual control, the K100D takes this round hands down. For true pocket portability and grab-and-go convenience, the VS20 is a smart skinny fit.

Sensor Technology: More Pixels or Bigger Pixels?

Here’s where these two cameras fundamentally diverge: sensor size and resolution, the ultimate image quality factors.

The K100D incorporates a 6-megapixel APS-C CCD sensor measuring 23.5 x 15.7 mm (~369 mm²). This is a relatively large sensor for its time - and even compared to compacts today. Larger sensors mean bigger photosites for capturing light, which translates into better dynamic range, lower noise, and improved color fidelity, especially at base and low ISO speeds.

The VS20 uses a small 1/2.3-inch (6.08 x 4.56 mm, ~27.7 mm²) 16-megapixel CCD sensor. So, while it offers a much higher pixel count, each photosite is tiny. The crank-up in megapixels on a small sensor leads to higher noise, limited dynamic range, and less effective light gathering, especially in shadows and low light scenarios.

In real-world use, the K100D excels with punchier colors, smoother gradations, and better skin tone reproduction - critical for portraits and professional work. The VS20 can produce detailed images under good lighting but struggles with noise smearing fine details in dimmer environments.

The Viewfinder vs. LCD Showdown

Framing your shot and reviewing images is part of the experience. The two cameras come with very different approaches.

The K100D features a modest 2.5-inch fixed LCD with 210k dots. While not the brightest or sharpest, it’s adequate for quick playback and menu navigation but lags behind today’s standards.

Importantly, it offers a traditional optical pentamirror viewfinder that many photographers swear by for its zero lag and clear daytime visibility. It’s basic, but having a dedicated eye piece is a huge advantage for shooting in bright sunlight or tracking moving subjects.

The VS20 drops the viewfinder entirely, instead giving you a 3-inch, 460k-dot TFT color screen with an anti-reflective coating. The live preview is sharp and bright, handy for composing at odd angles or video use (albeit limited specs). Without a viewfinder, though, photographers can struggle under harsh daylight or during fast action shoots, as holding the camera away from your face can introduce shake.

Autofocus Speed and Accuracy: The Nuts and Bolts of Nailing the Shot

In my hands-on experience, autofocus (AF) can make or break a shoot, especially for wildlife, sports, or street photographers.

The Pentax K100D employs an 11-point phase-detection AF system with continuous autofocus capability. While not lightning fast by today’s mirrorless standards, it was above average for an entry DSLR in 2006. It works well for still subjects and decent for slow-moving subjects but doesn’t support face or eye detection. Tracking fast or erratic movement can be challenging - so for pro sports shooters, this is a major consideration.

The Optio VS20 uses a 3-point contrast-detection AF relying on live view to focus. It lacks phase detection, which makes it slower and less reliable for moving subjects. Tracking subjects continuously is limited, especially in low light or zoomed focal lengths. It does have autofocus tracking and multi-area AF modes, but these are not on par with DSLR systems. Face detection support is absent here too.

Needless to say, neither camera shines as a speed demon, but the K100D’s system is comparatively faster and more precise, suitable for portraits and casual wildlife. The VS20 is best for static or slow-moving scenes.

Image Quality in Different Genres of Photography

With sensor and AF differences stated, how do the cameras fare across the usual genres? I tested extensively and present detailed notes next.

Portrait Photography

Skin tones and pleasing bokeh are portrait photography staples.

• K100D: APS-C sensor plus Pentax KAF-mount lenses (151 lenses!) mean you get shallow depth-of-field control for that creamy background blur. The in-camera image stabilization helps nail sharpness at slower shutter speeds. Color reproduction of skin tones has a warm, natural appearance. The 11-point AF maps well to subject placement, making manual focus possible with confidence.
• VS20: While higher megapixels sound promising, the tiny sensor struggles with noise in skin shadows and can look plasticky at times. The zoom lens maxes aperture at f/3.1-4.8, which limits background blur - so portraits often look flat and busy behind the subject.

Landscape Photography

Dynamic range and resolution are crucial here.

• K100D: Despite a modest 6 MP count by today’s standards, the richer dynamic range captures subtle tonal transitions beautifully. Dust or weather sealing is absent, so be cautious outdoors. The DSLR’s sturdiness and ability to change lenses make it ideal for landscapes.
• VS20: The 16 MP sensor’s limited physical size hampers dynamic range. Shadows tend to clip, and highlights are prone to blowing out in tricky conditions. However, the longer zoom can creatively capture distant mountains or details in a single frame.

Wildlife Photography

This is often a butter zone for superzoom compacts with extended reach.

• K100D: Focus system and burst rate (3 fps) are okay for non-sports wildlife but may frustrate if you need fast acquisition on flitting birds. The 1.5x crop factor helps with tele-lenses from the KAF lens lineup.
• VS20: The superzoom lens spans 28–560 mm (20x optical), giving tremendous reach - a massive plus. However, slow autofocus performance diminishes its wildlife potential. Shutter lag and continuous shooting at 1 fps undercut catch rate.

Sports Photography

Neither camera is a sports-focused beast, but let's see.

• K100D: 3 fps shooting is workable but insufficient for high-speed action. AF tracking is rudimentary. Low-light performance is mediocre compared to modern cameras. Good for hobbyists shooting casual sports.
• VS20: Continuous shooting at 1 fps and slow AF make it a no-go for sports beyond static or posed shots.

Street Photography

Key needs: discretion, responsiveness, and low light capability.

• K100D: Bulkier and louder shutter mean it demands commitment and may attract attention. The mechanical feel is pleasurable but a bit slower to set up.
• VS20: Small, quiet, and easy to slip into a pocket. Great for candid snaps where you want to blend in. The lens zoom flexibility helps capture a variety of scenes. Low light is problematic, with noise creeping quickly.

Macro Photography

Close-focusing capability and image stabilization matter here.

• K100D: No dedicated macro mode but compatible lenses allow focusing close. Sensor-shift stabilization helps handheld shots. Manual focus aids precision.
• VS20: Excellent minimum focus distance of 3 cm lets you get tight on tiny subjects. Sensor-shift IS helps reduce blur, but limited resolution and small sensor hamper detail.

Night / Astro Photography

Long exposures and high ISO noise handling are critical.

• K100D: Max shutter speed of 30 seconds covers long exposures well. Max ISO 3200 with decent noise control for its class. Sensor size favors better signal-to-noise ratio. No timelapse feature sadly.
• VS20: Minimum shutter speed 4 seconds limits star trail shots. High ISO can go to 6400, but noise is rampant. Lack of RAW means less post-processing leeway.

Video Capabilities: A Modest Offering

Video was emerging on cameras during these years.

The K100D has no video recording at all - it’s strictly stills focused. Meanwhile, the VS20 supports 720p at 30 fps, albeit limited to Motion JPEG format. No microphone jack, no headphone port, and limited manual exposure means video is a nice bonus but more a toy than professional tool.

Battery Life and Storage: Practical Aspects

• K100D uses 4 x AA batteries - a double-edged sword. Convenient worldwide availability but heavier and sometimes less consistent power delivery compared to proprietary options. It stores images on a single SD/ MMC card slot.
• VS20 runs on a D-LI122 rechargeable battery, compact and efficient, but you'd best carry spares for a day out. Uses SD/SDHC/SDXC cards and has some internal memory. Storage wise, both are standard fare.

Connectivity and Extras

Neither model sports modern wireless features like Bluetooth or NFC. The VS20 has Eye-Fi card compatibility for wireless image transfer - a neat option for when it was new.

USB 2.0 ports on both ensure basic tethering and file transfer.

Build Quality and Weather Resistance

Neither camera offers weather sealing or rugged build qualities. The K100D’s sturdy DSLR chassis feels more durable, but neither is suited to hardcore outdoor abuse.

Price-to-Performance: What Does Your Buck Buy?

The K100D is discontinued, available only second-hand, generally priced modestly given its age but still commanding value for those wanting DSLR fundamentals on a tight budget.

The VS20, new around $105, is a bargain entry compact with a staggering zoom lens. If your wallet’s tight and portability is the number one goal, it’s tempting.

Wrapping Up: Who Should Buy Which?

Pentax K100D front Pentax K100D screen back Pentax VS20 front Pentax VS20 screen back

Looking across genres, here’s my no-nonsense take:

In-Depth Performance Scores According to My Reviews

I compiled a nuanced overall rating reflecting lab and real-world results:

And genre-specific scores, emphasizing the K100D’s DSLR edge versus the VS20’s zoom-centric versatility:

Final Thoughts: The Practical Photographer’s Verdict

If you want solid image quality, flexibility with lenses, and room to grow as a photographer - naturally gravitate toward the Pentax K100D. It’s a vintage gem that outperforms many newer point-and-shoots by a mile in core photographic aspects, despite lacking bells and whistles.

On the other hand, if effortless superzoom reach, top portability, and quick snapshots are your priority - and you can tolerate noisier images and limited controls - the Pentax Optio VS20 shines as a compact travel buddy.

In any case, knowing what you want to shoot and how you intend to shoot it guides this choice best. Neither camera is a professional workhorse anymore, but each has a distinct charm and purpose depending on your needs and budget.

If you’re a beginner itching to learn the ropes of exposure triangle, manual focus, and classic DSLR handling, the K100D is a thrifty classroom in a box. For the casual traveler who dislikes carrying bulking gear or who values zoom range over image specs, the VS20 is a versatile companion.

Whichever side you pick, remember: perfect photos come not from gear alone but from you knowing your camera inside and out - and getting out there to capture what inspires you.

Happy shooting!