Pentax K-3 Mark IIIvs A7S II
Pentax
Pentax K-3 Mark III (2021)
Starting from £1699 new
Best for DSLR enthusiasts & outdoor photographers
View Pentax K-3 Mark III
Sony
A7S II (2015)
Starting from £799 new
Best for Low-light video, documentary & available-light filmmaking
View A7S II
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.
Low-Light Video, Documentary & Available-Light Filmmaking — A7S II (2015): A landmark in mirrorless history — the first Sony with IBIS and internal 4K, its low-light video capability still impresses today at a used-market price.
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 II (2015)
- Filmmakers and videographers who want legendary low-light performance at a used-price discount
- Documentary shooters working in unpredictable available light conditions
- A7S III shooters who want a second Sony FE body for backup or B-camera use
- Budget-conscious video producers who want full-frame 4K with S-Log at an accessible price
Quick take: The pentax k-3 mark iii has the highest resolution at 26mp; the a7s ii is the most affordable. Scroll down for the full spec breakdown.
Full specifications
| Specification | Pentax K-3 Mark III (2021) | A7S II (2015) |
|---|---|---|
| Price | £1,699 | £799 |
| Sensor | 25.7MP APS-C BSI CMOS (AA-filterless) | 12.1MP full-frame BSI Exmor CMOS |
| Resolution | 25.7MP | 12.1MP |
| Video | 4K/30p, 1080p/60p | 4K/30p internal (full sensor readout), 1080p/120p, S-Log2/S-Log3 |
| Autofocus | SAFOX 13 phase-detect, 101-point (25 cross-type) | 169 phase-detect + 25 contrast AF — limited by modern standards |
| Stabilisation | 5.5-stop 5-axis IBIS (Shake Reduction III) | 5-axis IBIS — 4.5 stops (first Sony mirrorless with IBIS) |
| Burst Rate | 12fps | 5fps continuous |
| Battery Life | 800 shots (CIPA) | ~370 shots (CIPA) |
| Weight | 820g body only | 584g body only |
| Dimensions | 134.5 × 103.5 × 73.5mm | 126.9 × 95.7 × 60.3mm |
| Weather Sealed | Yes | Yes |
| Viewfinder | Optical pentaprism, 100% coverage, 1.05× magnification | EVF, 2.36M dots, 0.71× magnification |
| Screen | 3.2" tilting touchscreen | 3.0" tilting LCD, 1.23M dots |
| Mount | Pentax KF-mount | Sony FE mount (full-frame E-mount) |
| Memory Cards | Dual SD UHS-II | Dual SD UHS-I slots |
| Connectivity | USB-C, Wi-Fi, Bluetooth | USB Micro-B, Bluetooth (via app), Wi-Fi, 3.5mm mic jack |
Suitability by genre
| Genre | Pentax K-3 Mark III | A7S II |
|---|---|---|
| Landscape | — | |
| Wildlife | — | |
| Sports & Action | — | |
| Portrait | ||
| Travel | — | |
| Vlogging & Video | ||
| Low Light | — | |
| Wedding | — | |
| Street | — | |
| Sports | — |
More comparisons with Pentax K-3 Mark III
Camera family history