Overall Rating:

5

Pentax 645Z


  • Features:
  • Build/Handling:
  • Metering:
  • Autofocus:
  • AWB Colour:
  • Dynamic Range:
  • LCD viewfinder:

Pros:

  • 51.4-million-pixel CMOS sensor with no AA filter
  • Excellent value, used manual-focus 645 lenses available
  • Cheaper than the medium-format competition

Cons:

  • Weighs 1,470g
  • AF could be a little faster

Manufacturer:

Manufacturer:

Price as Reviewed:

£6,800.00

Its resolution is staggering, but there is much more to the 51.4-million-pixel Pentax 645Z medium-format digital camera. Richard Sibley finds out what it is like to use in our Pentax 645Z review

Resolution, Dynamic Range and Noise

Pentax 645Z Review – Resolution, Dynamic Range and Noise

Pentax 645Z – Resolution

Pentax 645Z res charts

Thanks to its 51-million-pixel sensor and no optical low-pass filter, the 645Z can deliver an extraordinary amount of detail. At ISO 100, it resolves close to 6000l/ph, before maze-like aliasing becomes visible, and the CMOS sensor means images stay almost as detailed up to ISO 1600. Resolution falls at higher sensitivities, to around 4800l/ph at ISO 25,600 and 4000l/ph at ISO 102,400 – which is still pretty impressive.

Pentax 645Z – Dynamic Range

Pentax 645Z dynamic range

The 645Z delivers the highest dynamic range of any camera we’ve tested so far, at over 13EV at ISO 100. This should translate to huge amounts of shadow detail in raw files. Unlike previous CCD-based medium-format systems, the dynamic range holds up very well at higher sensitivities, with almost 10EV at ISO 3200. Beyond this it falls progressively, but it’s still more than a match for full-frame cameras such as the Nikon D810.

Pentax 645Z – Noise

Pentax 645Z noise

Images are extremely clean at ISO 100, and still very usable at ISO 3200. Noise becomes increasingly evident thereafter, with ISO 12,800 looking obviously gritty. At ISO 51,200 luminance noise is extremely pronounced, and the highest ISOs are barely acceptable. Indeed, the noise is so severe at ISO 204,800 that our grey card has taken on an overall greenish tint.

  • Sensor: 51.4-million-pixel, 44 x 33mm CMOS sensor
  • Output size: 8256 x 6192 pixels
  • Focal length mag: 0.8x
  • Lens mount: Pentax 645AF2
  • Shutter speeds: 30-1/4000
  • ISO: 100-204,800
  • Metering system: 86,000-pixel RGB sensor
  • Exposure compensation: +/-5EV in 1/3 EV steps
  • Drive mode: 3fps
  • LCD: Tiltable 3.2in, 1/04-million dots
  • Viewfinder: Keplerian telescopic trapezoid prism finder
  • AF points: 27 (25 cross-type)
  • Video: 1920 x 1080 pixels at 60i/50i/30p/25p/24p
  • External mic: Yes
  • Memory card: SD/SDHC/SDXC or Flucards
  • Power: Rechargeable Lithium-ion battery D-LI90
  • Dimensions: 117 x 156 x 123mm
  • Weight: 1,470g

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