Pentax K-3 Mark IIIvs A7S
Pentax
Pentax K-3 Mark III (2021)
Starting from £1699 new
Best for DSLR enthusiasts & outdoor photographers
View Pentax K-3 Mark III
GearScore™ Verdict — Which should you buy?
Dslr Enthusiasts & Outdoor Photographers — Pentax K-3 Mark III (2021): The finest APS-C DSLR ever made — class-leading weather sealing, optical viewfinder, 5-axis IBIS, and extraordinary build for photographers committed to DSLR.
Astrophotography & Low-Light — A7S (2014): The original A7S pioneered the concept of a camera optimised entirely for low light. Its 12.2MP sensor has enormous photosites — extraordinary high-ISO performance that still holds up. Lacking IBIS and limited to 1080p internally (4K requires external recorder), it is a specialist tool. For astrophotography, event videography, or any scenario where light is genuinely scarce, it remains outstanding.
Who should buy what
Pentax K-3 Mark III (2021)
- 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
A7S (2014)
- Astrophotographers
- Low-light event videographers
- Filmmakers needing clean high-ISO footage
Quick take: The pentax k-3 mark iii has the highest resolution at 26mp; the a7s is the most affordable. Scroll down for the full spec breakdown.
Full specifications
| Specification | Pentax K-3 Mark III (2021) | A7S (2014) |
|---|---|---|
| Price | £1,699 | £600 |
| Sensor | 25.7MP APS-C BSI CMOS (AA-filterless) | 12.2MP Full-Frame BSI CMOS |
| Resolution | 25.7MP | 12.2MP |
| Video | 4K/30p, 1080p/60p | 1080p/60p internal, 4K via HDMI (external recorder) |
| Autofocus | SAFOX 13 phase-detect, 101-point (25 cross-type) | Phase-detect / contrast-detect hybrid AF |
| Stabilisation | 5.5-stop 5-axis IBIS (Shake Reduction III) | None |
| Burst Rate | 12fps | 5fps |
| Battery Life | 800 shots (CIPA) | ~370 shots (CIPA) |
| Weight | 820g body only | 474g (with battery and card) |
| Dimensions | 134.5 × 103.5 × 73.5mm | 126.9 × 94.4 × 48.2mm |
| Weather Sealed | Yes | Yes |
| Viewfinder | Optical pentaprism, 100% coverage, 1.05× magnification | Electronic, 2.36M dots, 0.71× magnification |
| Screen | 3.2" tilting touchscreen | 3.0" tilting LCD, 1.23M dots |
| Mount | Pentax KF-mount | Sony FE (full-frame E-mount) |
| Memory Cards | Dual SD UHS-II | Single SD / MemoryStick PRO Duo slot |
| Connectivity | USB-C, Wi-Fi, Bluetooth | Multi/Micro USB, Wi-Fi, NFC |
Suitability by genre
| Genre | Pentax K-3 Mark III | A7S |
|---|---|---|
| Landscape | ||
| Wildlife | — | |
| Sports & Action | ||
| Portrait | ||
| Travel | ||
| Vlogging & Video | ||
| Astrophotography | — | |
| Street | — |
GearScore™ suitability scores are based on aggregated purchaser reviews weighted by photography genre. See how scores are calculated →
More comparisons with Pentax K-3 Mark III
Camera family history