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Pentax

K-3 Mark III Monochrome

Monochrome-only APS-C DSLR with 25.7MP sensor, IBIS, optical viewfinder, and weather sealing.

$2,199

Launch price

Released Apr 2024

vs
Alpha 1 II

Sony

Alpha 1 II

50MP stacked flagship with 30fps RAW, 8K video, and Sony's fastest hybrid performance.

$6,499

Launch price

Released Nov 2024

Alpha 1 II is 7 months newer.

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Wins

2categories

K-3 Mark III Monochrome

WildlifePortrait

Wins

13categories

Alpha 1 II

Sports & ActionVideo & Hybrid

3 categories tied

Which would you choose?

TL;DR — Key differences

K-3 Mark III Monochrome wins 0 categories·Alpha 1 II wins 5 categories
  • BAlpha 1 II has higher AF points / zones (759 vs 101)
  • BAlpha 1 II has higher EVF resolution (9,437,184 vs 3,690,000)
  • BAlpha 1 II has higher 4K max frame rate (120 fps vs 60 fps)
  • BAlpha 1 II has higher EVF refresh rate (240 Hz vs 120 Hz)
  • BAlpha 1 II has higher Resolution (50.1 MP vs 25.7 MP)

Key specs at a glance

K-3 Mark III MonochromeAlpha 1 II
Resolution25.7 MP50.1 MP
SensorAPS-CFull Frame
ISO max25,60032,000
Burst20 fps30 fps
4K60 fps120 fps
IBIS5.5-stop8.5-stop
Weight820 g743 g
Battery640 shots520 shots

Size and weight, to scale

K-3 Mark III Monochrome

135 × 104 × 74 mm

820 g (1.81 lb / 28.92 oz)

Credit card shown to scale as a size reference (ISO 7810, 85.6 × 54 mm)

Credit card

85.6 × 54 mm

for scale

Alpha 1 II front view

Alpha 1 II

136 × 97 × 83 mm

743 g (1.64 lb / 26.21 oz)

K-3 Mark III Monochrome is 2mm narrower and 9mm thinner than Alpha 1 II but it is also 7mm taller.

K-3 Mark III Monochrome is 77 g heavier than Alpha 1 II.

Depth (front-to-back): 74mm K-3 Mark III Monochrome · 83mm Alpha 1 II

Sensor size, to scale

K-3 Mark III Monochrome

23.5 × 15.6 mm · APS-C

367 mm² area

Alpha 1 II

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 Monochrome

Pentax K

70+

native lenses available

30 first-party40 third-party

Alpha 1 II

✓ more lenses

Sony E

350+

native lenses available

80 first-party270 third-party

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

Use caseK-3 Mark III MonochromeAlpha 1 II
Portrait
6.5Good
8.5Excellent✓ wins
Sports & Action
6.5Good
10.0Excellent✓ wins
Video & Hybrid
6.0Good
9.5Excellent✓ wins
Landscape
5.0Fair
9.0Excellent✓ wins
Travel
6.5Good✓ wins
6.0Good
Wildlife
10.0Excellent✓ wins
9.5Excellent
Vlogging
5.5Fair
5.5Fair

Why pick one over the other

Reasons to choose

K-3 Mark III Monochrome

  • Dimensions (W×H×D mm)

    Adds 134.5, 103.5, 73.5

  • Subject recognition

    Adds Vehicle

  • Battery life (CIPA)

    640 shots vs 520 shots — higher is better

  • AF frame coverage

    100 % vs 94 % — higher is better

Reasons to choose

Alpha 1 II

  • AF low-light limit

    -4 EV vs -3 EV — lower is better

  • Dimensions (W×H×D mm)

    Adds 136.1, 96.9, 82.9

  • AF points / zones

    759 vs 101 — higher is better

  • EVF resolution

    9,437,184 vs 3,690,000 — higher is better

  • Codecs

    Adds XAVC HS, XAVC S, XAVC S-I

  • AA filter

    Only Alpha 1 II supports it

  • Subject recognition

    Adds Insect, Car/Train, Airplane

  • 4K max frame rate

    120 fps vs 60 fps — higher is better

Both cameras share

  • ISO min (native)Both 100
  • Eye AFBoth support eye af
  • Animal / bird AFBoth support animal / bird af
  • Pre-Capture / Pre-ReleaseBoth support pre-capture / pre-release
  • Max video bit rateBoth 150 Mbps
  • In-body stabilization (IBIS)Both support in-body stabilization (ibis)

Pros & cons at a glance

Editorially curated highlights and trade-offs.

K-3 Mark III Monochrome

Pros

  • Dedicated monochrome sensor
  • Optical viewfinder
  • IBIS in a DSLR
  • Weather sealed

Cons

  • Black-and-white only
  • DSLR platform
  • Limited video

Alpha 1 II

Pros

  • 50MP stacked sensor
  • 30fps blackout-free burst
  • 8K 30p video
  • Best Sony AF

Cons

  • Very expensive
  • Complex menus
  • Large files

Decided which one is right for you?

Compare live prices for the K-3 Mark III Monochrome and Alpha 1 II at major authorized retailers.

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Full specifications

= category winner

K-3 Mark III Monochrome
Alpha 1 II
Resolution
25.7 MP
50.1 MP+95%
Sensor type
Monochrome APS-C CMOS
Full Frame Stacked Exmor RS CMOS
Sensor size
23.5 × 15.6 mm
35.9 × 24.0 mm
AA filter
No
Yes
K-3 Mark III Monochrome
Alpha 1 II
Processor
Image processor
BIONZ XR + AI processing unit
K-3 Mark III Monochrome
Alpha 1 II
ISO min (native)
100
100
ISO max (native)
25,600
32,000+0.3 stops
ISO max (expanded)
102,400
102,400
K-3 Mark III Monochrome
Alpha 1 II
Shutter type
Mechanical + Electronic
Mechanical + Electronic
Max mechanical speed
1/8000 sec
1/8000 sec
Max electronic speed
1/16000 sec
1/32000 sec

Frequently asked

Quick answers generated from verified specs.

Which is better for landscape, K-3 Mark III Monochrome or Alpha 1 II?

Alpha 1 II scores 9.0/10 versus 5.0/10 for K-3 Mark III Monochrome — 50.1MP — massive detail for large prints.

What's the resolution difference between the K-3 Mark III Monochrome and Alpha 1 II?

K-3 Mark III Monochrome is 25.7 MP and Alpha 1 II is 50.1 MP, so the Alpha 1 II captures more detail for cropping and large prints.

Do the K-3 Mark III Monochrome and Alpha 1 II have in-body image stabilization?

K-3 Mark III Monochrome has 5.5-stop in-body image stabilization, while Alpha 1 II has 8.5-stop in-body image stabilization.

Which shoots faster bursts — the K-3 Mark III Monochrome or the Alpha 1 II?

K-3 Mark III Monochrome reaches 20 fps electronic. Alpha 1 II reaches 30 fps electronic.

What's the weight difference between the K-3 Mark III Monochrome and Alpha 1 II?

K-3 Mark III Monochrome weighs 820 g and Alpha 1 II weighs 743 g, so the Alpha 1 II is 77 g lighter.

Do the K-3 Mark III Monochrome and Alpha 1 II record 4K video?

K-3 Mark III Monochrome: 4K up to 60p. Alpha 1 II: 8K (max), 4K up to 120p.

Are the K-3 Mark III Monochrome and Alpha 1 II weather sealed?

K-3 Mark III Monochrome: Yes. Alpha 1 II: Yes.

Which has better battery life?

Rated battery life is 640 shots (CIPA) for the K-3 Mark III Monochrome and 520 shots for the Alpha 1 II, giving the K-3 Mark III Monochrome the edge.

How much does each cost?

K-3 Mark III Monochrome launched at $2,199 and Alpha 1 II at $6,499. The K-3 Mark III Monochrome is $4,300 less.

Can't decide between two? Compare a third camera.

Add any camera to get a three-way K-3 Mark III Monochrome vs Alpha 1 II vs X comparison.

Specs sourced from manufacturer data. Use-case scores algorithmically derived. Last reviewed June 2026.

Product images courtesy of Pentax and Sony press materials.