EOS R100vs A7 IIIvs A7 IV
Which should you buy?
First Camera / Beginner Photography — EOS R100 (2023): The R100 does the basics well at the lowest possible price point. Its main value is as a gateway into the Canon RF ecosystem — the lenses you buy now will work on any Canon body you upgrade to later. Modest ambitions, reliably met.
All-Round Photography & Video — A7 III (2018): Still one of the best all-round cameras money can buy — particularly strong used. The A7 III proved that full-frame doesn't have to mean compromises, and nothing at this price point has meaningfully beaten it.
Portrait & Wedding Photography — A7 IV (2021): The full-frame portrait benchmark — 33MP, AI Eye AF, and exceptional skin-tone rendering in a pro-grade hybrid body.
Who should buy what
EOS R100 (2023)
- First-time camera buyers stepping up from a smartphone
- Students and hobbyists wanting an affordable starting point
- Anyone who wants to start investing in Canon RF glass on a budget
- Casual photographers who don't need advanced video or speed
A7 III (2018)
- Enthusiast photographers upgrading from APS-C for the first time
- Working photographers who need reliable AF and weather sealing
- Anyone who shoots in low light regularly
- Hybrid shooters needing both stills and video performance
A7 IV (2021)
- You want a high-resolution full-frame all-rounder for portraits, weddings, or travel
- You're stepping up from APS-C or a DSLR and want the best all-round full-frame body under £3,000
- You shoot a mix of stills and video and need a single body that handles both seriously
- You want access to the widest lens ecosystem in the mirrorless market
Quick take: The a7 iv has the highest resolution at 33mp; the eos r100 is the most affordable; only the a7 iii, a7 iv are weather sealed. Scroll down for the full spec breakdown.
Full specifications
| Specification | EOS R100 (2023) | A7 III (2018) | A7 IV (2021) |
|---|---|---|---|
| Price | £529 | £1,699 | £2,299 |
| Sensor | 24.1MP APS-C CMOS | 24.2MP Full-Frame Exmor R BSI CMOS | 33MP Full-frame BSI Exmor R CMOS |
| Resolution | 24.1MP | 24.2MP | 33.0MP |
| Video | 4K/30p (slight crop), 1080p/60p | 4K/30p (6K oversampled), 1080p/120p slow-motion | 4K/60p oversampled, 10-bit internal, S-Log3, S-Cinetone |
| Autofocus | Dual Pixel CMOS AF, face detection, subject tracking | Phase-detect, 693 points, real-time Eye AF & animal AF | 759-point phase-detect, AI subject recognition |
| Stabilisation | None (no IBIS) | 5-axis IBIS, 5 stops | 5-axis IBIS, 5.5 stops |
| Burst Rate | 6.5fps mechanical | 10fps with AF/AE tracking | 10fps mechanical, 30fps electronic |
| Battery Life | ~270 shots (CIPA) | ~710 shots (CIPA) | ~580 shots (CIPA) |
| Weight | 356g (body, battery, card) | 565g (body, battery, card) | 659g body only |
| Dimensions | 116.3 × 85.5 × 68.8mm | 126.9 × 95.6 × 73.7mm | 131.3 × 96.4 × 79.8mm |
| Weather Sealed | No | Yes | Yes |
| Viewfinder | EVF, 2.36M dots, 0.59× magnification | EVF, 2.36M dots, 0.78× magnification | EVF, 3.69M dots, 0.78× magnification |
| Screen | 3.0" fixed touchscreen, 1.04M dots | 3.0" tilting touchscreen, 921k dots | 3.0" vari-angle touchscreen |
| Mount | Canon RF-mount | Sony E-mount | Sony FE (full-frame E-mount) |
| Memory Cards | Single SD UHS-II | Dual SD (UHS-II slot 1, UHS-I slot 2) | Dual slots: CFexpress Type A + SD UHS-II |
| Connectivity | USB-C, Wi-Fi, Bluetooth | USB-C (USB 3.2), Wi-Fi, Bluetooth, NFC | USB-C (3.2 Gen 2), Bluetooth, Wi-Fi |
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