Andy Westlake tests Pentax's latest fully featured mid-range DSLR with in-body image stabilisation

Product Overview

Overall rating:

Pentax K-70

Features:9/10
Build/Handling:8/10
Metering:8/10
Autofocus:7/10
AWB Colour:7/10
Dynamic Range:8/10
Image quality:8/10
LCD viewfinder:9/10

Pros:

  • Effective in-body image stabilisation that works with every lens
  • Large, bright viewfinder is the best in class
  • Good contingent of external controls makes it easy to change settings

Cons:

  • Relatively slow and clunky live view
  • In-camera JPEG processing needs a lot of twekaing for the best results
  • LCD screen isn't touch sensitive

Product:

Pentax K-70 review

Manufacturer:

Price as reviewed:

£559.00 (body only)

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Pentax K-70 review – Dynamic range, resolution and noise

With its 24-million-pixel APS-C sensor, the K-70 offers image quality that’s at least a match for its peers and can only really be surpassed by much more expensive full-frame models. With a good lens, it records lots of detail at high ISOs, and image quality stands up really well as the ISO is raised. I was quite happy shooting at ISO 3200, and could live with ISO 25,600 at a pinch, but would avoid the top two settings. Raw shooters will be pleased to find that it can record using Adobe’s open-standard DNG format, which means that unlike other new models, you probably won’t need to update your raw conversion software to handle its files.

Dynamic range

Pentax K-70 dynamic range graph

The K-S2 delivers very acceptable results in our Applied Imaging tests, broadly in line with its bigger brother the K-3 II, which also uses a 24-million-pixel APS-C sensor. Starting at 12.3EV at ISO 100, the readings initially decline only slowly to ISO 1600, where we still record almost 11EV. Beyond this, fall-off is more marked, indicating rapidly increasing noise levels, particularly in the shadows. By ISO 25,600, dynamic range has declined to a barely acceptable 6.3EV, with the higher ISO settings recording even lower readings, confirming their very marginal quality.

Resolution

Pentax K-70 - Resolution ISO 100 (JPEG)

JPEG ISO 100

Pentax K-70 - Resolution ISO 400 (JPEG)

JPEG ISO 400

Pentax K-70 - Resolution ISO 6400 (JPEG)

JPEG ISO 6400

Pemtax K-70 - Resolution ISO 102400

JPEG ISO 102400

When shooting in raw, the K-70 can resolve at least 3600 lines/picture height. But the lack of a low-pass filter means that this comes with some moiré and false colour. This is suppressed by the camera’s JPEG processing, resulting in a clear drop in resolution to around 3200l/ph. Increasing the ISO further reduces resolution, to around 3000l/ph at ISO 6400 and 2600l/ph at ISO 25,600. The AA Filter Simulator reduces resolution to 3400l/ph at the Type 1 setting and 3000l/ph at Type 2, while reducing imaging artefacts.

Noise

Pentax K-70 - JPEG ISO 100

JPEG ISO 100

Pentax K-70 - JPEG ISO 400

JPEG ISO 400

Pentax K-70 - JPEG ISO 1600

JPEG ISO 1600

Pentax K-70 - JPEG ISO 6400

JPEG ISO 6400

Pentax K-70 - JPEG ISO 25600

JPEG ISO 25600

Both raw and JPEG images taken from our diorama scene are captured at the full range of ISO settings. The camera is placed in its default setting for JPEG images. Raw images are sharpened and noise reduction applied, to strike the best balance between resolution and noise.

Looking at our standard test scene, the K-70 delivers detailed, noise-free results at ISO 100, which are a match for any current APS-C camera. As the sensitivity is raised, noise gradually increases, with the finest detail starting to suffer at around ISO 800. Even so, settings up to ISO 3200 are still eminently usable, and it’s only at ISO 6400 that low-frequency colour noise can start to creep into the camera’s JPEG files. At higher settings this gets more visible, as does luminance noise in the midtones, and personally I’d steer clear of ISO 51,200 and 102,400 unless it’s absolutely necessary, as the image quality at these settings is very marginal indeed. Switch to shooting raw and you get more control over noise reduction, which means that those top two sensitivity settings become slightly more usable, if still very much for emergencies only.

  1. 1. At a glance
  2. 2. Pentax K-70 - Features
  3. 3. Pentax K-70 - Viewfinder and screen
  4. 4. Pentax K-70 - Build and handling
  5. 5. Pentax K-70 - Autofocus
  6. 6. Pentax K-70 - Performance
  7. 7. Pentax K-70 - Pixel Shift Resolution
  8. 8. Pentax K-70 review - Dynamic range, resolution and noise
  9. 9. Pentax K-70 - Verdict
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