Canon
EOS R1
Flagship 24.2MP full-frame BSI stacked RF body with 40fps burst, Dual Pixel Intelligent AF, 6K RAW, and 9.44M-dot EVF.
$6,299
Released Jul 2024
Pentax
K-3 Mark III
APS-C DSLR flagship with optical viewfinder and weather sealing.
$1,999
Released Apr 2021
EOS R1 is 3.3 years newer.
Wins
EOS R1
Wins
K-3 Mark III
3 categories tied
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TL;DR — Key differences
- AEOS R1 has higher AF points / zones (1053 vs 101)
- AEOS R1 has higher ISO max (native) (102,400 vs 25,600)
- AEOS R1 has higher EVF resolution (9,440,000 vs 3,690,000)
- BK-3 Mark III has lower Weight (520 g vs 1115 g)
- AEOS R1 has higher Burst (electronic) (40 fps vs 20 fps)
Key specs at a glance
Size and weight, to scale
EOS R1
158 × 150 × 87 mm
1115 g (2.46 lb / 39.33 oz)
K-3 Mark III
138 × 98 × 88 mm
520 g (1.15 lb / 18.34 oz)
EOS R1 is 1mm thinner than K-3 Mark III but it is also 20mm wider and 52mm taller.
EOS R1 is 595 g heavier than K-3 Mark III.
Depth (front-to-back): 87mm EOS R1 · 88mm K-3 Mark III
Back view, to scale
Width × Height — same proportions as the front of the body.
EOS R1
158 × 150 mm
K-3 Mark III
138 × 98 mm
Top view, to scale
Width × Depth (front-to-back) — see which body is chunkier on the table.
EOS R1
158 × 87 mm
K-3 Mark III
138 × 88 mm
Sensor size, to scale
EOS R1
36 × 24 mm · Full Frame
864 mm² area
K-3 Mark III
23.5 × 15.6 mm · APS-C
367 mm² area
2.4× larger sensor area = shallower depth of field and better low-light performance.
Lens ecosystem
Native lens selection
EOS R1
✓ more lensesCanon RF
105+
native lenses available
K-3 Mark III
Pentax K
70+
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
EOS R1
AF low-light limit
-7.5 EV vs -3 EV — lower is better
Subject recognition
Adds People, Dogs, Cats…
Dimensions (W×H×D mm)
Adds 157.6, 149.5, 87.3
Card types
Adds CFexpress Type B, CFexpress Type B
AF points / zones
1053 vs 101 — higher is better
ISO max (native)
102,400 vs 25,600 — higher is better
EVF resolution
9,440,000 vs 3,690,000 — higher is better
Codecs
Adds RAW, XF-HEVC S, XF-AVC S
Reasons to choose
K-3 Mark III
Subject recognition
Adds Human, Animal, Bird…
Dimensions (W×H×D mm)
Adds 138, 98, 88
Card types
Adds SD UHS-II
Weight
520 g vs 1115 g — lower is better
Resolution
25.7 MP vs 24.2 MP — higher is better
Both cameras share
- ✓ISO min (native) — Both 100
- ✓AF frame coverage — Both 100 %
- ✓Eye AF — Both support eye af
- ✓Animal / bird AF — Both support animal / bird af
- ✓Pre-Capture / Pre-Release — Both support pre-capture / pre-release
- ✓In-body stabilization — Both support in-body stabilization
Pros & cons at a glance
Editorially curated highlights and trade-offs.
EOS R1
Pros
- ✓40fps electronic burst
- ✓24.2MP BSI stacked full-frame sensor
- ✓Dual Pixel Intelligent AF
- ✓6K RAW and 4K 120p video
- ✓Dual CFexpress Type B slots
Cons
- –24MP resolution
- –Very expensive
- –Large integrated-grip body
K-3 Mark III
Pros
- ✓Optical viewfinder
- ✓Weather sealed
- ✓IBIS in DSLR
Cons
- –DSLR system declining
- –APS-C
- –Limited video
Full specifications
✓ = category winner
Frequently asked
Quick answers generated from verified specs.
Which is better for travel, EOS R1 or K-3 Mark III?
K-3 Mark III scores 8.5/10 versus 4.5/10 for EOS R1 — 520g — compact and travel-friendly.
What's the resolution difference between the EOS R1 and K-3 Mark III?
EOS R1 is 24.2 MP and K-3 Mark III is 25.7 MP, so the K-3 Mark III captures more detail for cropping and large prints.
Do the EOS R1 and K-3 Mark III have in-body image stabilization?
EOS R1 has 8.5-stop in-body image stabilization, while k-3 Mark III has 7-stop in-body image stabilization.
Which shoots faster bursts — the EOS R1 or the K-3 Mark III?
EOS R1 reaches 40 fps electronic. K-3 Mark III reaches 20 fps electronic.
What's the weight difference between the EOS R1 and K-3 Mark III?
EOS R1 weighs 1115 g and K-3 Mark III weighs 520 g, so the K-3 Mark III is 595 g lighter.
Do the EOS R1 and K-3 Mark III record 4K video?
EOS R1: 6K RAW (max), 4K up to 120p. K-3 Mark III: 4K up to 60p.
Are the EOS R1 and K-3 Mark III weather sealed?
EOS R1: Yes. K-3 Mark III: Yes.
How much does each cost?
EOS R1 launched at $6,299 and K-3 Mark III at $1,999. The K-3 Mark III is $4,300 less.
Specs sourced from manufacturer data. Use-case scores algorithmically derived. Last reviewed May 2026.
Product images courtesy of Canon and Pentax press materials.