Pentax
K-3 Mark III
APS-C DSLR flagship with optical viewfinder and weather sealing.
$1,999
Released Apr 2021
Sony
Alpha 7R VI
66.8MP fully-stacked full-frame high-resolution body with 30fps bursts, 8K 30p, 4K 120p, and Sony's new BIONZ XR2 engine.
$4,499
Released Jun 2026
Alpha 7R VI is 5.1 years newer.
Wins
K-3 Mark III
Wins
Alpha 7R VI
2 categories tied
TL;DR — Key differences
- BAlpha 7R VI has higher AF points / zones (759 vs 101)
- BAlpha 7R VI has higher Max video bit rate (600 Mbps vs 150 Mbps)
- BAlpha 7R VI has higher Resolution (66.8 MP vs 25.7 MP)
- BAlpha 7R VI has higher EVF resolution (9,437,184 vs 3,690,000)
- BAlpha 7R VI has higher 4K max frame rate (120 fps vs 60 fps)
Key specs at a glance
Size and weight, to scale
K-3 Mark III
138 × 98 × 88 mm
520 g (1.15 lb / 18.34 oz)
Alpha 7R VI
133 × 97 × 83 mm
713 g (1.57 lb / 25.15 oz)
K-3 Mark III is 5mm wider, 1mm taller, and 5mm thicker than Alpha 7R VI.
K-3 Mark III is 193 g lighter than Alpha 7R VI.
Depth (front-to-back): 88mm K-3 Mark III · 83mm Alpha 7R VI
Back view, to scale
Width × Height — same proportions as the front of the body.
K-3 Mark III
138 × 98 mm
Alpha 7R VI
133 × 97 mm
Top view, to scale
Width × Depth (front-to-back) — see which body is chunkier on the table.
K-3 Mark III
138 × 88 mm
Alpha 7R VI
133 × 83 mm
Sensor size, to scale
K-3 Mark III
23.5 × 15.6 mm · APS-C
367 mm² area
Alpha 7R VI
35.9 × 24 mm · Full Frame
862 mm² area
2.3× larger sensor area = shallower depth of field and better low-light performance.
Lens ecosystem
Native lens selection
K-3 Mark III
Pentax K
70+
native lenses available
Alpha 7R VI
✓ 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
K-3 Mark III
Dimensions (W×H×D mm)
Adds 138, 98, 88
Card types
Adds SD UHS-II
Pre-Capture / Pre-Release
Only K-3 Mark III supports it
Weather sealing
Only K-3 Mark III supports it
Weight
520 g vs 713 g — lower is better
Battery life (CIPA)
640 shots vs 600 shots — higher is better
Reasons to choose
Alpha 7R VI
AF low-light limit
-6 EV vs -3 EV — lower is better
Dimensions (W×H×D mm)
Adds 132.7, 96.9, 82.9
Card types
Adds CFexpress Type A, SDXC UHS-II
AF points / zones
759 vs 101 — higher is better
Max video bit rate
600 Mbps vs 150 Mbps — higher is better
Resolution
66.8 MP vs 25.7 MP — higher is better
EVF resolution
9,437,184 vs 3,690,000 — higher is better
Codecs
Adds XAVC HS, XAVC S, XAVC S-I
Both cameras share
- ✓ISO min (native) — Both 100
- ✓Eye AF — Both support eye af
- ✓Animal / bird AF — Both support animal / bird af
- ✓In-body stabilization — Both support in-body stabilization
- ✓Card slots — Both 2
- ✓Touchscreen — Both support touchscreen
Pros & cons at a glance
Editorially curated highlights and trade-offs.
K-3 Mark III
Pros
- ✓Optical viewfinder
- ✓Weather sealed
- ✓IBIS in DSLR
Cons
- –DSLR system declining
- –APS-C
- –Limited video
Alpha 7R VI
Pros
- ✓66.8MP fully-stacked Exmor RS sensor
- ✓30fps blackout-free electronic burst
- ✓8K 30p and 4K 120p video
- ✓8.5-stop in-body stabilization
- ✓9.44M-dot HDR OLED EVF
Cons
- –Very expensive
- –Large files demand fast cards and storage
- –8K workflow can be heavy
Full specifications
✓ = category winner
Frequently asked
Quick answers generated from verified specs.
Which is better for travel, K-3 Mark III or Alpha 7R VI?
K-3 Mark III scores 8.5/10 versus 5.0/10 for Alpha 7R VI — 520g — compact and travel-friendly.
What's the resolution difference between the K-3 Mark III and Alpha 7R VI?
K-3 Mark III is 25.7 MP and Alpha 7R VI is 66.8 MP, so the Alpha 7R VI captures more detail for cropping and large prints.
Do the K-3 Mark III and Alpha 7R VI have in-body image stabilization?
K-3 Mark III has 7-stop in-body image stabilization, while alpha 7R VI has in-body image stabilization.
Which shoots faster bursts — the K-3 Mark III or the Alpha 7R VI?
K-3 Mark III reaches 20 fps electronic. Alpha 7R VI reaches 30 fps electronic.
What's the weight difference between the K-3 Mark III and Alpha 7R VI?
K-3 Mark III weighs 520 g and Alpha 7R VI weighs 713 g, so the K-3 Mark III is 193 g lighter.
Do the K-3 Mark III and Alpha 7R VI record 4K video?
K-3 Mark III: 4K up to 60p. Alpha 7R VI: 8K (max), 4K up to 120p.
Are the K-3 Mark III and Alpha 7R VI weather sealed?
K-3 Mark III: Yes. Alpha 7R VI: No.
Which has better battery life?
Rated battery life is 640 shots (CIPA) for the K-3 Mark III and 600 shots for the Alpha 7R VI, giving the K-3 Mark III the edge.
How much does each cost?
K-3 Mark III launched at $1,999 and Alpha 7R VI at $4,499. The K-3 Mark III is $2,500 less.
Specs sourced from manufacturer data. Use-case scores algorithmically derived. Last reviewed May 2026.
Product images courtesy of Pentax and Sony press materials.