Pentax
Pentax K-3 Mark III 2021
Best for DSLR enthusiasts & outdoor photographers
£1699
list price · used from £856 at eBay
Decision tools · Compare
Pentax K-3 Mark III vs A5100
Quick take: The Pentax K-3 Mark III has the highest resolution at 26MP; the A5100 is the most affordable; only the Pentax K-3 Mark III is weather sealed.
16 specs side by side·16 genres scored·UK prices from Wex Photo Video and Clifton Cameras
How to read this page. Highlighted cells win that row on the spec alone. Genre scores are the engine's base scores (enthusiast, photo and video); Camera Match re-weights them for your level and priorities. Price buttons are affiliate links; the price you pay is the same.
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Verdictwhich should you buy?
Pentax K-3 Mark III — Dslr Enthusiasts & Outdoor Photographers: The finest APS-C DSLR ever made — class-leading weather sealing, optical viewfinder, 5-axis IBIS, and extraordinary build for photographers committed to DSLR.
A5100 — Casual & Travel: The A5100 is one of the smallest APS-C mirrorless cameras ever made. Its 24MP sensor, phase-detect AF, and selfie-friendly flip screen pack remarkable capability into a shirt-pocket-sized body. No EVF or hot shoe limits it for serious use, but as a compact travel camera or beginner's first mirrorless, it punches well above its price on the used market.
Who should buy what
Pentax K-3 Mark III (2021)
is the right camera for you if…
- DSLR photographers who want the finest APS-C optical viewfinder experience
- Outdoor and weather photographers who need robust all-weather sealing
- Pentax lens owners who want to use their existing K-mount glass
- Photographers who prefer optical viewfinders and refuse to switch to mirrorless
A5100 (2014)
is the right camera for you if…
- Beginners stepping up from a smartphone
- Compact travel photographers
- Casual vloggers who want APS-C quality
Full specificationsthe better value in each row is highlighted
| Specification | Pentax K-3 Mark IIIPentax · 2021 | A5100Sony · 2014 |
|---|---|---|
| Price | £1,699 | £200Best |
| Sensor | 25.7MP APS-C BSI CMOS (AA-filterless) | 24.3MP APS-C Exmor CMOS |
| Resolution | 25.7MPBest | 24.3MP |
| Video | 4K/30p, 1080p/60p | 1080p/60p |
| Autofocus | SAFOX 13 phase-detect, 101-point (25 cross-type) | Hybrid phase-detect / contrast-detect AF, face detection |
| Stabilisation | 5.5-stop 5-axis IBIS (Shake Reduction III) | No stabilisation |
| Burst Rate | 12fpsBest | 6fps |
| Battery Life | 800 shots (CIPA)Best | ~400 shots (CIPA) |
| Weight | 820g (body only) | 224g (body only)Best |
| Dimensions | 134.5 × 103.5 × 73.5mm | 109.6 × 62.8 × 35.7mm |
| Weather Sealed | YesBest | Not weather sealed |
| Viewfinder | Optical pentaprism, 100% coverage, 1.05× magnification | No viewfinder |
| Screen | 3.2" fixed touchscreen | 3.0" flip-up touchscreen, 921k dots |
| Mount | Pentax KF-mount | Sony E-mount |
| Memory Cards | Dual SD UHS-II | Single SD / MemoryStick PRO Duo slot |
| Connectivity | USB-C, Wi-Fi, Bluetooth | Micro USB, Wi-Fi, NFC |
Wins the row — price, resolution, burst, battery, weight and sealing are compared; text specs aren't ranked.
How they score by genreengine base scores out of 10
Genre
Pentax K-3 Mark III
A5100
Portrait
6.6/10
5.4/10
Street
5.2/10
7.0/10
Travel
5.5/10
6.7/10
Wedding & Events
7.0/10
3.5/10
Filmmaking
5.4/10
—
Documentary
6.4/10
4.1/10
Sports & Action
6.8/10
4.7/10
Landscape
6.2/10
5.0/10
Wildlife
6.8/10
5.5/10
Casual
4.3/10
5.1/10
Food
5.4/10
5.9/10
Macro
4.9/10
5.2/10
Architecture
6.0/10
5.2/10
Astrophotography
6.5/10
4.7/10
Vlogging & Video
—
5.0/10
Fun & simple
—
4.5/10
Scores come from the same engine as Camera Match: verified specifications weighted by what each genre needs, with documented adjustments. The product page and this table show the enthusiast base score. See how scores are calculated →
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