Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | OM System - OM-1 Mark II | Sony - α7C II |
|---|---|---|
| Weight | 599 g | 514 g |
| Megapixels | 20 MP | 33 MP |
| AF points | 1053 | 759 |
| Sensor size | Four Thirds | Full Frame |
Between the OM-1 Mark II and α7C II, the OM-1 Mark II comes out ahead in af points, while the α7C II wins on weight / megapixels. Overall, the OM-1 Mark II scores 67.4 and the α7C II scores 71.7 on our Mars Score.
Which should you buy?
The α7C II edges ahead on the Mars Score (67.4 vs 71.7), but the 4.3-point gap is small enough that the right pick comes down to which spec advantages matter to you.
Pick the OM-1 Mark II if you care most about af points. The biggest gaps in its favor are af points. The single most decisive one: AF points — 38.74% more. 1053 vs 759.
Pick the α7C II if you carry the device everywhere and weight or thickness has been the deciding factor before. Its strongest claims are weight, megapixels, sensor size. The single most decisive one: Weight — 85.00 g less. 514 vs 599.
Both ship with comparable max video, in-body stabilization, log profile, so those specs do not separate the two — focus on the differences below.
Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity says both are well-rounded; the differences are about trade-offs, not quality.
Which should you buy: OM System - OM-1 Mark II or Sony - α7C II?
Sony - α7C II leads the current Mars Score by 4.3 points.The more useful decision is the trade-off behind that result: compare megapixels, sensor size, weight against the way you will actually use the product.
Choose OM System - OM-1 Mark II if…
OM System - OM-1 Mark II has the measurable edge on af points.
Choose Sony - α7C II if…
Sony - α7C II has the measurable edge on weight g, megapixels, sensor size.
This is a structured comparison of the published catalog values. It is not a claim of identical real-world performance across every workload; use the linked spec drill-downs and methodology page to inspect the inputs.
Why OM System - OM-1 Mark II wins
- ▲AF points — 38.74% more. 1053 vs 759.
Why Sony - α7C II wins
- ▲Weight — 85.00 g less. 514 vs 599.
- ▲Megapixels — 65.00% more. 33 MP vs 20 MP.
- ▲Sensor size: Full Frame (vs Four Thirds).
Spec comparison
Sensor
| Spec | OM System - OM-1 Mark II | Sony - α7C II |
|---|---|---|
| Sensor sizeⓘ | Four Thirds | Full Framelead |
| Megapixels | 20 MP | 33 MPlead |
| Max ISO | 102400lead | 51200 |
Video
| Spec | OM System - OM-1 Mark II | Sony - α7C II |
|---|---|---|
| Max video | 4K60 | 4K60 |
| RAW video | false | false |
| Log profileⓘ | true | true |
Autofocus
| Spec | OM System - OM-1 Mark II | Sony - α7C II |
|---|---|---|
| AF pointsⓘ | 1053lead | 759 |
| Eye AFⓘ | true | true |
| In-body stabilizationⓘ | true | true |
Body & Controls
| Spec | OM System - OM-1 Mark II | Sony - α7C II |
|---|---|---|
| Weight | 599 g | 514 glead |
| Weather sealedⓘ | true | true |
| Dual card slotsⓘ | truelead | false |