Canon
EOS R3
Pro 24MP full-frame stacked-sensor body built for sports, news, wildlife, and high-speed hybrid capture.
$5,999
Launch priceReleased Sep 2021
Pentax
K-3 Mark III
APS-C DSLR flagship with optical viewfinder and weather sealing.
$1,999
Launch priceReleased Apr 2021
EOS R3 is 5 months newer.
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Wins
EOS R3
Wins
K-3 Mark III
4 categories tied
Which would you choose?
TL;DR — Key differences
- AEOS R3 has higher Max video bit rate (2600 Mbps vs 150 Mbps)
- AEOS R3 has higher AF points / zones (1053 vs 101)
- AEOS R3 has higher ISO max (native) (102,400 vs 25,600)
- AEOS R3 has higher 4K max frame rate (120 fps vs 60 fps)
- BK-3 Mark III has lower Weight (520 g vs 1015 g)
Key specs at a glance
Size and weight, to scale
📸 Snap this size diff to shareEOS R3
150 × 143 × 87 mm
1015 g (2.24 lb / 35.80 oz)
Credit card
85.6 × 54 mm
for scale
K-3 Mark III
138 × 98 × 88 mm
520 g (1.15 lb / 18.34 oz)
EOS R3 is 1mm thinner than K-3 Mark III but it is also 12mm wider and 45mm taller.
EOS R3 is 495 g heavier than K-3 Mark III.
Depth (front-to-back): 87mm EOS R3 · 88mm K-3 Mark III
Sensor size, to scale
EOS R3
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 R3
✓ 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 R3
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 150, 142.6, 87.2
Max video bit rate
2600 Mbps vs 150 Mbps — higher is better
AF points / zones
1053 vs 101 — higher is better
ISO max (native)
102,400 vs 25,600 — higher is better
AA filter
Only EOS R3 supports it
4K max frame rate
120 fps vs 60 fps — higher is better
Reasons to choose
K-3 Mark III
Subject recognition
Adds Human, Animal, Bird…
Dimensions (W×H×D mm)
Adds 138, 98, 88
Pre-Capture / Pre-Release
Only K-3 Mark III supports it
Weight
520 g vs 1015 g — lower is better
Resolution
25.7 MP vs 24.1 MP — higher is better
Battery life (CIPA)
640 shots vs 620 shots — higher is better
EVF magnification
0.78 × vs 0.76 × — 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
- ✓In-body stabilization (IBIS) — Both support in-body stabilization (ibis)
- ✓Weather sealing — Both support weather sealing
Pros & cons at a glance
Editorially curated highlights and trade-offs.
EOS R3
Pros
- ✓30fps electronic burst from a stacked full-frame sensor
- ✓Exceptional low-light AF down to -7.5 EV
- ✓Integrated pro body with large LP-E19 battery
- ✓6K RAW video and 4K 120p
- ✓Rugged weather-sealed construction
Cons
- –24MP resolution trails higher-detail rivals
- –Large integrated-grip body
- –Expensive compared with enthusiast full-frame bodies
K-3 Mark III
Pros
- ✓Optical viewfinder
- ✓Weather sealed
- ✓IBIS in DSLR
Cons
- –DSLR system declining
- –APS-C
- –Limited video
Decided which one is right for you?
Compare live prices for the EOS R3 and K-3 Mark III at major authorized retailers.
Canon EOS R3
Pentax K-3 Mark III
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Full specifications
✓ = category winner
Frequently asked
Quick answers generated from verified specs.
Which is better for wildlife, EOS R3 or K-3 Mark III?
K-3 Mark III scores 10.0/10 versus 5.0/10 for EOS R3 — 20fps burst captures fleeting moments.
What's the resolution difference between the EOS R3 and K-3 Mark III?
EOS R3 is 24.1 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 R3 and K-3 Mark III have in-body image stabilization?
EOS R3 has 8-stop in-body image stabilization, while K-3 Mark III has 7-stop in-body image stabilization.
Which shoots faster bursts — the EOS R3 or the K-3 Mark III?
EOS R3 reaches 30 fps electronic. K-3 Mark III reaches 20 fps electronic.
What's the weight difference between the EOS R3 and K-3 Mark III?
EOS R3 weighs 1015 g and K-3 Mark III weighs 520 g, so the K-3 Mark III is 495 g lighter.
Do the EOS R3 and K-3 Mark III record 4K video?
EOS R3: 6K RAW (max), 4K up to 120p. K-3 Mark III: 4K up to 60p.
Are the EOS R3 and K-3 Mark III weather sealed?
EOS R3: Yes. K-3 Mark III: Yes.
Which has better battery life?
Rated battery life is 620 shots (CIPA) for the EOS R3 and 640 shots for the K-3 Mark III, giving the K-3 Mark III the edge.
How much does each cost?
EOS R3 launched at $5,999 and K-3 Mark III at $1,999. The K-3 Mark III is $4,000 less.
Can't decide between two? Compare a third camera.
Add any camera to get a three-way EOS R3 vs K-3 Mark III vs X comparison.
Specs sourced from manufacturer data. Use-case scores algorithmically derived. Last reviewed July 2026.