Image Quality Compared

Our latest test scene simulates both daylight and low-light shooting. Pressing the 'lighting' buttons at the top of the widget switches between the two. The daylight scene is manually white balanced to give neutral grays, but the camera is left in its Auto setting for the low-light tests. Raw files are manually corrected. We offer three different viewing sizes: 'Full', 'Print', and 'Comp', with the latter two offering 'normalized' comparisons by using matched viewing sizes. The 'Comp' option chooses the largest-available resolution common to the cameras being compared.

The K-70 houses a very good 24-megapixel sensor that in some ways is let down by its JPEG engine. More specifically, it is let down by the default settings (which are used in this test, and by many users), particularly in terms of sharpening. Thankfully, there are better sharpening options available.* A glance at the scene's text shows the Pentax looking out of focus compared to the D5500. A quick glance at Raw shows this isn't the case. In fact, Raw files from the Pentax show plenty of detail and aliasing where one would expect. In terms of resolution and reproduction, it is right on par with the Nikon (especially if they had the exact same lens). 

Behind these JPEG shortcomings, however, is a very good sensor. At the Canon's maximum ISO, the K-70 performs a full stop better. It bests the D5500 at ISO 25600, and even competes with higher tier cameras like the D7200 and a6300. However, at least part of this impressive performance may be a bit of in-camera noise reduction, with evidence of this showing in our ISO invariance test, as well as edge artifacts and visible dotting in high ISO images.

Colors, while pleasingly saturated, tend to run on the cooler side, especially compared to the very warm Nikon. Reds appear redder (less orange) because of this, but yellows and oranges aren't as pleasingly warm, and most images in our K-70 gallery appear rather cool. Greens are also more blue-shifted. Skintones are less saturated next to Nikon, and have less warmth compared to Canon. The Canon's slightly cooler rendition next to Nikon means the Pentax isn't too far off from the T6i - a good thing given the generally highly regarded Canon colors.

High ISO JPEGs are decent, but aren't class leading. Color and detail are well-preserved, although largely due to the very mild noise reduction. While the mild NR helps prevent the smoothing out of detail, it does a poor job removing chroma noise. That means large areas of solid color, like the background of our studio scene, show faint green and magenta blocking, which shows in the real-world as well. 

Raw Dynamic Range

In our exposure latitude test, where files are underexposed intentionally and then lifted back to a normal exposure in post-processing, performance of the K-70 is right on par with the D5500, to the point where it suggests the two probably use the same sensor. Either choice is well ahead of the T6i for those that need flexible Raw output.

ISO Invariance

This test allows us to see how much noise a camera adds at base ISO compared to an image where amplification is applied by increasing the ISO. As we can see in the test, there is a similar amount of noise in the ISO 3200 shot and the ISO 100 shot pushed to match the ISO 3200 shot. Both cameras show a bit more noise in the pushed shot, meaning they're not truly iso-invariant and there is a slight benefit to shooting at a higher ISO for a given scene. Still, it does mean it's possible to maintain your aperture and shutter speed values, lower the ISO and capture an image with more highlight information with very little noise cost. 

A close look at the Pentax reveals a slight blur to the noise pattern on the ISO 3200 shot, which suggest that the camera 'bakes' the Raw file with a bit of added noise reduction when ISO is increased.


*Sharpening is greatly improved when changed to 'Fine Sharpness' or 'Extra Sharpness', which makes us wonder why 'Fine Sharpness' isn't the factory default. This setting isn't in plain view (hint: you have to enter the 'Custom Image' menu, then hit 'Info' to enter the 'Parameter Adjustment' menu, then the rear dial toggles the different sharpness options).