OM System
OM-3
Retro-styled MFT body with modern AF and creator-friendly design.
$1,699
Launch priceReleased Jan 2025
Sony
Alpha 7 III
Classic 24MP hybrid that defined the modern full-frame value proposition.
$1,999
Launch priceReleased Feb 2018
OM-3 is 6.9 years newer.
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Wins
OM-3
Wins
Alpha 7 III
2 categories tied
Which would you choose?
TL;DR — Key differences
- AOM-3 has higher Burst (electronic) (120 fps vs 10 fps)
- AOM-3 has higher Max video bit rate (205 Mbps vs 100 Mbps)
- BAlpha 7 III has lower ISO min (native) (100 vs 200)
- BAlpha 7 III has higher ISO max (native) (51,200 vs 25,600)
- BAlpha 7 III has higher Card slots (2 vs 1)
Key specs at a glance
Size and weight, to scale
📸 Snap this size diff to share
OM-3
139 × 89 × 46 mm
413 g (0.91 lb / 14.57 oz)
Credit card
85.6 × 54 mm
for scale
Alpha 7 III
127 × 96 × 74 mm
650 g (1.43 lb / 22.93 oz)
OM-3 is 7mm shorter and 28mm thinner than Alpha 7 III but it is also 12mm wider.
OM-3 is 237 g lighter than Alpha 7 III.
Depth (front-to-back): 46mm OM-3 · 74mm Alpha 7 III
Back view, to scale
Width × Height — same proportions as the front of the body.
OM-3
139 × 89 mm
Credit card
85.6 × 54 mm
Alpha 7 III
127 × 96 mm
Top view, to scale
Width × Depth (front-to-back) — see which body is chunkier on the table.
OM-3
139 × 46 mm
Credit card
85.6 × 54 mm
Alpha 7 III
127 × 74 mm
Sensor size, to scale
OM-3
17.4 × 13 mm · Compact / large-type
226 mm² area
Alpha 7 III
35.6 × 23.8 mm · Full Frame
847 mm² area
3.7× larger sensor area = shallower depth of field and better low-light performance.
Lens ecosystem
Native lens selection
OM-3
Micro Four Thirds
130+
native lenses available
Alpha 7 III
✓ more lensesSony E
350+
native lenses available
Counts include current first-party and major third-party native autofocus lenses.
Use-case scoring
Which one for what?
Algorithmic scores from verified specs · 10 = best in class
Why pick one over the other
Reasons to choose
OM-3
AF low-light limit
-5.5 EV vs -3 EV — lower is better
Subject recognition
Adds People, Birds, Animals…
Dimensions (W×H×D mm)
Adds 139.3, 88.9, 45.8
Card types
Adds SD, SDHC, SDXC
Burst (electronic)
120 fps vs 10 fps — higher is better
Codecs
Adds H.265, MOV, MPEG-4 AVC
Max video bit rate
205 Mbps vs 100 Mbps — higher is better
Pre-Capture / Pre-Release
Only OM-3 supports it
Reasons to choose
Alpha 7 III
Subject recognition
Adds Human, Animal
Dimensions (W×H×D mm)
Adds 126.9, 95.6, 73.7
Card types
Adds SD UHS-II, SD UHS-I
Codecs
Adds XAVC S, AVCHD
AA filter
Only Alpha 7 III supports it
ISO min (native)
100 vs 200 — lower is better
ISO max (native)
51,200 vs 25,600 — higher is better
Card slots
2 vs 1 — higher is better
Both cameras share
- ✓Eye AF — Both support eye af
- ✓Animal / bird AF — Both support animal / bird af
- ✓Burst (mechanical) — Both 10 fps
- ✓In-body stabilization (IBIS) — Both support in-body stabilization (ibis)
- ✓Weather sealing — Both support weather sealing
- ✓EVF refresh rate — Both 120 Hz
Pros & cons at a glance
Editorially curated highlights and trade-offs.
OM-3
Pros
- ✓Retro design
- ✓Modern AF
- ✓Compact
Cons
- –MFT sensor
- –Premium for MFT
- –Smaller lens selection
Alpha 7 III
Pros
- ✓Proven reliability
- ✓Great battery life
- ✓Strong value used
- ✓Dual card slots
Cons
- –Older AF vs newer bodies
- –4K 30p only
- –No 10-bit internal
Decided which one is right for you?
Compare live prices for the OM-3 and Alpha 7 III at major authorized retailers.
OM System OM-3
Sony Alpha 7 III
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Full specifications
✓ = category winner
Frequently asked
Quick answers generated from verified specs.
Which is better for sports, OM-3 or Alpha 7 III?
OM-3 scores 8.5/10 versus 4.0/10 for Alpha 7 III — 120fps burst — pro-level action capture.
What's the resolution difference between the OM-3 and Alpha 7 III?
OM-3 is 20.4 MP and Alpha 7 III is 24.2 MP, so the Alpha 7 III captures more detail for cropping and large prints.
Do the OM-3 and Alpha 7 III have in-body image stabilization?
OM-3 has 6.5-stop in-body image stabilization, while Alpha 7 III has 5-stop in-body image stabilization.
Which shoots faster bursts — the OM-3 or the Alpha 7 III?
OM-3 reaches 120 fps electronic. Alpha 7 III reaches 10 fps electronic.
What's the weight difference between the OM-3 and Alpha 7 III?
OM-3 weighs 413 g and Alpha 7 III weighs 650 g, so the OM-3 is 237 g lighter.
Do the OM-3 and Alpha 7 III record 4K video?
OM-3: 4K up to 59.94p. Alpha 7 III: 4K up to 30p.
Are the OM-3 and Alpha 7 III weather sealed?
OM-3: Yes. Alpha 7 III: Yes.
Which has better battery life?
Rated battery life is 640 shots (CIPA) for the OM-3 and 710 shots for the Alpha 7 III, giving the Alpha 7 III the edge.
How much does each cost?
OM-3 launched at $1,699 and Alpha 7 III at $1,999. The OM-3 is $300 less.
Can't decide between two? Compare a third camera.
Add any camera to get a three-way OM-3 vs Alpha 7 III vs X comparison.
Specs sourced from manufacturer data. Use-case scores algorithmically derived. Last reviewed September 2026.
Product images courtesy of OM System and Sony press materials.