OM System
OM-3 ASTRO
Astrophotography-focused OM-3 variant with 20.4MP stacked sensor, H-alpha-friendly filter tuning, IP53 sealing, and 7.5-stop Sync IS.
$2,499
Released Jul 2025
Sony
Alpha 7 IV
33MP hybrid all-rounder with 10-bit 4K 60p and AI-powered subject tracking.
$2,499
Released Oct 2021
OM-3 ASTRO is 3.7 years newer.
Wins
OM-3 ASTRO
Wins
Alpha 7 IV
4 categories tied
TL;DR — Key differences
- AOM-3 ASTRO has higher Burst (electronic) (120 fps vs 10 fps)
- BAlpha 7 IV has higher Max video bit rate (600 Mbps vs 150 Mbps)
- AOM-3 ASTRO has higher ISO max (native) (102,400 vs 51,200)
- BAlpha 7 IV has higher Card slots (2 vs 1)
- BAlpha 7 IV has higher Resolution (33 MP vs 20.4 MP)
Key specs at a glance
Size and weight, to scale
OM-3 ASTRO
139 × 89 × 46 mm
496 g (1.09 lb / 17.50 oz)
Alpha 7 IV
131 × 96 × 80 mm
658 g (1.45 lb / 23.21 oz)
OM-3 ASTRO is 8mm shorter and 34mm thinner than Alpha 7 IV but it is also 8mm wider.
OM-3 ASTRO is 162 g lighter than Alpha 7 IV.
Depth (front-to-back): 46mm OM-3 ASTRO · 80mm Alpha 7 IV
Sensor size, to scale
OM-3 ASTRO
17.4 × 13 mm · Compact / large-type
226 mm² area
Alpha 7 IV
35.9 × 23.9 mm · Full Frame
858 mm² area
3.8× larger sensor area = shallower depth of field and better low-light performance.
Lens ecosystem
Native lens selection
OM-3 ASTRO
Micro Four Thirds
130+
native lenses available
Alpha 7 IV
✓ 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 ASTRO
AF low-light limit
-8 EV vs -4 EV — lower is better
Subject recognition
Adds People, Birds, Animals…
Dimensions (W×H×D mm)
Adds 139.3, 88.9, 45.8
Burst (electronic)
120 fps vs 10 fps — higher is better
ISO max (native)
102,400 vs 51,200 — higher is better
Pre-Capture / Pre-Release
Only OM-3 ASTRO supports it
Card types
Adds SD UHS-I
Codecs
Adds MOV
Reasons to choose
Alpha 7 IV
Subject recognition
Adds Human, Animal, Bird…
Dimensions (W×H×D mm)
Adds 131.3, 96.4, 79.8
Max video bit rate
600 Mbps vs 150 Mbps — higher is better
Codecs
Adds XAVC HS, XAVC S, XAVC S-I
AA filter
Only Alpha 7 IV supports it
Internal RAW video
Only Alpha 7 IV supports it
Card slots
2 vs 1 — higher is better
Card types
Adds CFexpress Type A
Both cameras share
- ✓Eye AF — Both support eye af
- ✓Animal / bird AF — Both support animal / bird af
- ✓Burst (mechanical) — Both 10 fps
- ✓4K max frame rate — Both 60 fps
- ✓In-body stabilization — Both support in-body stabilization
- ✓Weather sealing — Both support weather sealing
Pros & cons at a glance
Editorially curated highlights and trade-offs.
OM-3 ASTRO
Pros
- ✓Astro-tuned sensor filter
- ✓20.4MP stacked BSI Live MOS
- ✓IP53 weather sealing
- ✓7.5-stop Sync IS
Cons
- –Specialized astro variant
- –Micro Four Thirds sensor
- –Premium price
Alpha 7 IV
Pros
- ✓33MP — more detail for cropping and print
- ✓10-bit 4K 60p (Super35 crop) / 4K 30p full-frame
- ✓Full-size HDMI port
- ✓759 phase-detect AF points
Cons
- –4K 60p requires Super35 crop
- –10fps burst lags behind R6 II at 40fps
- –Complex menu system
Full specifications
✓ = category winner
Frequently asked
Quick answers generated from verified specs.
Which is better for portraits, OM-3 ASTRO or Alpha 7 IV?
Alpha 7 IV scores 9.0/10 versus 4.0/10 for OM-3 ASTRO — 33MP — ample resolution for portraits.
What's the resolution difference between the OM-3 ASTRO and Alpha 7 IV?
OM-3 ASTRO is 20.4 MP and Alpha 7 IV is 33 MP, so the Alpha 7 IV captures more detail for cropping and large prints.
Do the OM-3 ASTRO and Alpha 7 IV have in-body image stabilization?
OM-3 ASTRO has 6.5-stop in-body image stabilization, while alpha 7 IV has 5.5-stop in-body image stabilization.
Which shoots faster bursts — the OM-3 ASTRO or the Alpha 7 IV?
OM-3 ASTRO reaches 120 fps electronic. Alpha 7 IV reaches 10 fps electronic.
What's the weight difference between the OM-3 ASTRO and Alpha 7 IV?
OM-3 ASTRO weighs 496 g and Alpha 7 IV weighs 658 g, so the OM-3 ASTRO is 162 g lighter.
Do the OM-3 ASTRO and Alpha 7 IV record 4K video?
OM-3 ASTRO: 4K up to 60p. Alpha 7 IV: 4K up to 60p.
Are the OM-3 ASTRO and Alpha 7 IV weather sealed?
OM-3 ASTRO: Yes. Alpha 7 IV: Yes.
Which has better battery life?
Rated battery life is 640 shots (CIPA) for the OM-3 ASTRO and 580 shots for the Alpha 7 IV, giving the OM-3 ASTRO the edge.
How much does each cost?
Both launched at $2,499.
Specs sourced from manufacturer data. Use-case scores algorithmically derived. Last reviewed May 2026.
Product images courtesy of OM System and Sony press materials.