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Pentax

645Z

51MP medium format DSLR that made digital MF accessible — still prized for landscape and studio.

$8,499

Launch price

Released Apr 2014

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vs

Pentax

K-S2

Compact weather-sealed APS-C DSLR with 20MP sensor, AA filter simulator, and built-in Wi-Fi.

$799

Launch price

Released Feb 2015

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K-S2 is 10 months newer.

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Wins

7categories

645Z

★ Wildlife★ Landscape

Wins

1categories

K-S2

★ Wildlife★ Sports & Action

10 categories tied

Which would you choose?

TL;DR — Key differences

645Z wins 4 categories·K-S2 wins 1 categories
  • A645Z has higher Resolution (51.4 MP vs 20.1 MP)
  • BK-S2 has lower Weight (678 g vs 1470 g)
  • A645Z has higher RAW buffer depth (120 frames vs 60 frames)
  • A645Z has higher EVF resolution (3,690,000 vs 2,360,000)
  • A645Z has lower ISO min (native) (64 vs 100)

Key specs at a glance

645ZK-S2
Resolution51.4 MP20.1 MP
Sensor43.8 × 32.8 mmAPS-C
ISO max25,60025,600
Burst20 fps15 fps
4K60 fps60 fps
IBIS7-stop6-stop
Weight1470 g678 g
Battery640 shots640 shots

Size and weight, to scale

645Z

156 × 117 × 123 mm

1470 g (3.24 lb / 51.85 oz)

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

Credit card

85.6 × 54 mm

for scale

K-S2

123 × 91 × 77 mm

678 g (1.49 lb / 23.92 oz)

645Z is 34mm wider, 26mm taller, and 46mm thicker than K-S2.

645Z is 792 g heavier than K-S2.

Depth (front-to-back): 123mm 645Z · 77mm K-S2

Sensor size, to scale

645Z

43.8 × 32.8 mm · Medium Format

1437 mm² area

K-S2

23.5 × 15.6 mm · APS-C

367 mm² area

3.9× larger sensor area = shallower depth of field and better low-light performance.

Lens ecosystem

Native lens selection

645Z: mount data unavailable

K-S2

✓ more lenses

Pentax K

70+

native lenses available

30 first-party40 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 case645ZK-S2
Portrait
6.0Good✓ wins
5.5Fair
Sports & Action
6.5Good
6.5Good
Video & Hybrid
6.0Good
6.0Good
Landscape
8.0Excellent✓ wins
3.5Limited
Travel
5.5Fair
6.5Good✓ wins
Wildlife
9.0Excellent
9.0Excellent
Vlogging
5.5Fair
5.5Fair

Why pick one over the other

Reasons to choose

645Z

  • Dimensions (W×H×D mm)

    Adds 156, 117, 123

  • Resolution

    51.4 MP vs 20.1 MP — higher is better

  • RAW buffer depth

    120 frames vs 60 frames — higher is better

  • EVF resolution

    3,690,000 vs 2,360,000 — higher is better

  • ISO min (native)

    64 vs 100 — lower is better

  • Burst (mechanical)

    8 fps vs 6 fps — higher is better

  • Burst (electronic)

    20 fps vs 15 fps — higher is better

  • IBIS effectiveness

    7 stops vs 6 stops — higher is better

Reasons to choose

K-S2

  • Dimensions (W×H×D mm)

    Adds 122.5, 91.4, 76.9

  • Weight

    678 g vs 1470 g — lower is better

Both cameras share

  • ✓AA filter — Both support aa filter
  • ✓ISO max (native) — Both 25,600
  • ✓AF points / zones — Both 101
  • ✓AF frame coverage — Both 100 %
  • ✓Eye AF — Both support eye af
  • ✓Animal / bird AF — Both support animal / bird af

Pros & cons at a glance

Editorially curated highlights and trade-offs.

645Z

Pros

  • ✓51MP medium format
  • ✓CMOS sensor
  • ✓Pentax color
  • ✓Relatively affordable MF

Cons

  • –Huge body
  • –Slow operation
  • –Limited lens line vs Hasselblad

K-S2

Pros

  • ✓Weather sealed
  • ✓Compact DSLR
  • ✓AA filter simulator
  • ✓Wi-Fi

Cons

  • –20MP dated
  • –No IBIS
  • –DSLR niche

Decided which one is right for you?

Compare live prices for the 645Z and K-S2 at major authorized retailers.

Pentax 645Z

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Pentax K-S2

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Full specifications

✓ = category winner

645Z
K-S2
Resolution
51.4 MP✓2.6× more
20.1 MP
Sensor type
Medium Format CMOS
APS-C CMOS
Sensor size
43.8 × 32.8 mm
23.5 × 15.6 mm
AA filter
Yes
Yes
645Z
K-S2
Processor
Image processor
Image processor
645Z
K-S2
ISO min (native)
64✓−36 less
100
ISO max (native)
25,600
25,600
ISO max (expanded)
102,400
102,400
645Z
K-S2
Shutter type
Mechanical + Electronic
Mechanical + Electronic
Max mechanical speed
1/8000 sec
1/8000 sec
Max electronic speed
1/16000 sec
1/16000 sec

Frequently asked

Quick answers generated from verified specs.

Which is better for landscape, 645Z or K-S2?

645Z scores 8.0/10 versus 3.5/10 for K-S2 — 51.4MP — massive detail for large prints.

What's the resolution difference between the 645Z and K-S2?

645Z is 51.4 MP and K-S2 is 20.1 MP, so the 645Z captures more detail for cropping and large prints.

Do the 645Z and K-S2 have in-body image stabilization?

645Z has 7-stop in-body image stabilization, while K-S2 has 6-stop in-body image stabilization.

Which shoots faster bursts — the 645Z or the K-S2?

645Z reaches 20 fps electronic. K-S2 reaches 15 fps electronic.

What's the weight difference between the 645Z and K-S2?

645Z weighs 1470 g and K-S2 weighs 678 g, so the K-S2 is 792 g lighter.

Do the 645Z and K-S2 record 4K video?

645Z: 4K up to 60p. K-S2: 4K up to 60p.

Are the 645Z and K-S2 weather sealed?

645Z: Yes. K-S2: Yes.

Which has better battery life?

Rated battery life is 640 shots (CIPA) for the 645Z and 640 shots for the K-S2, giving the K-S2 the edge.

How much does each cost?

645Z launched at $8,499 and K-S2 at $799. The K-S2 is $7,700 less.

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

Add any camera to get a three-way 645Z vs K-S2 vs X comparison.

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