OM-3vs A7S
OM System
OM-3 (2024)
Starting from £999 new
Best for Travel, outdoor & adventure photography
View OM-3
GearScore™ Verdict — Which should you buy?
Travel, Outdoor & Adventure Photography — OM-3 (2024): The ideal mid-range OM System camera — weather sealed, class-leading IBIS, and superb computational features in a compact body.
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
OM-3 (2024)
- Outdoor and adventure photographers who need weather sealing and compact size
- Wildlife and bird photographers wanting improved AF over the OM-5
- Travel shooters who want a rugged, lightweight MFT system
- OM-5 or E-M5 III owners wanting better autofocus without going to the OM-1
A7S (2014)
- Astrophotographers
- Low-light event videographers
- Filmmakers needing clean high-ISO footage
Quick take: The om-3 has the highest resolution at 20mp; the a7s is the most affordable. Scroll down for the full spec breakdown.
Full specifications
| Specification | OM-3 (2024) | A7S (2014) |
|---|---|---|
| Price | £999 | £600 |
| Sensor | 20.4MP Live MOS Micro Four Thirds | 12.2MP Full-Frame BSI CMOS |
| Resolution | 20.4MP | 12.2MP |
| Video | 4K/60p (10-bit), C4K/30p, 1080p/120p | 1080p/60p internal, 4K via HDMI (external recorder) |
| Autofocus | Phase-detect AF — subject recognition (human, animal, bird, vehicle) | Phase-detect / contrast-detect hybrid AF |
| Stabilisation | IBIS — up to 6.5 stops (7.5 stops with Sync IS lenses) | None |
| Burst Rate | 10fps mechanical, 30fps electronic with AF | 5fps |
| Battery Life | ~400 shots (CIPA) | ~370 shots (CIPA) |
| Weight | 414g (with battery) | 474g (with battery and card) |
| Dimensions | 122.3 × 84.6 × 49.4mm | 126.9 × 94.4 × 48.2mm |
| Weather Sealed | Yes | Yes |
| Viewfinder | EVF, 2.36M dots, 0.74× magnification | Electronic, 2.36M dots, 0.71× magnification |
| Screen | 3.0" fully articulating touchscreen | 3.0" tilting LCD, 1.23M dots |
| Mount | Micro Four Thirds | Sony FE (full-frame E-mount) |
| Memory Cards | Single SD UHS-II slot | Single SD / MemoryStick PRO Duo slot |
| Connectivity | USB-C, Wi-Fi, Bluetooth | Multi/Micro USB, Wi-Fi, NFC |
Suitability by genre
| Genre | OM-3 | A7S |
|---|---|---|
| Travel | ||
| Wildlife | — | |
| Landscape | ||
| Street | ||
| Portrait | ||
| Vlogging & Video | ||
| Astrophotography | — | |
| Sports & Action | — |
GearScore™ suitability scores are based on aggregated purchaser reviews weighted by photography genre. See how scores are calculated →
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Camera family history