Pentax K-S2 Review

Sharpness and Noise

With the increased resolution and no AA filter, K-S2's sensor is impressively sharp, as demonstrated below:

Sharpness test subject

100% crop

In fact, the camera is so sharp that the default JPEG sharpening will oftentimes backfire when the body is paired with a sharp lens, such as a prime. Consider the following scene, shot with the FA 43mm F1.9 Limited at F5.6— where its sharpness peaks:

Sharpness test scene

Now, looking at a full-size crop, notice the difference between the trees in the RAW and the JPEG:

The JPEG almost looks artificial— perhaps like a watercolor painting— because it is over-sharpened.  A high-resolution sensor without an AA filter that's then also paired with a sharp lens simply does not call for any additional in-camera sharpening.  To avoid this issue, all you need to do is turn the Custom Image sharpness all the way down.  A custom User mode can be used for this purpose whenever shooting with prime lenses or professional zooms.

The fact that this is necessary is a testament to the K-S2's resolving power.  Let's take a look at a few more full-size files:

Sample photo taken with the 18-50mm kit lens (view original)

We find this degree of detail to be impressive for such a simple snapshot.  Things get even better with a dedicated macro lens:

Sample photo taken with the D FA 100mm macro (click to enlarge, or view original)

You can safely increase the ISO during the day and still get plenty of detail, too:

Sample macro at ISO 800 (click to enlarge, or view original)

All three of the images above are unedited JPEG files straight out of camera shot with the Bright image profile.

Noise

We will refer you to our Pentax K-S1 review for detailed comparative tests of the 20.2 megapixel sensor's noise performance.  The benefit of added resolution in the new sensor is greater than the associated increase in noise, making it excellent for low-light photography.  Detail loss in daytime files is negligible up to ISO 800 and the camera holds its ground well up to ISO 3200.

Overall, the K-S2 is a step above the Pentax K-50 while falling short of the 24-megapixel sensor in the K-3 flagship, as is to be expected.

High-ISO Shadow Recovery

After confirming that the K-S2's performance is consistent with that of the K-S1, we proceeded to dig a little bit deeper to see how the K-S2 fares when it comes to shadow recovery in low light.  The highlighted area is underexposed by about two stops.

Low-light test scene

Use the dropdowns below to cycle between images.  In-camera noise reduction was disabled in the JPEGs and only baseline NR was applied to the RAW files.

Reasonable shadow recovery is possible up to ISO 800, which is quite impressive.  Also notice how the RAW files are more detailed but also slightly more noisy.  Generally-speaking, Pentax cameras apply a great deal of noise reduction to JPEG files, even when the noise reduction setting is disabled.  We thus recommend the use of RAW when the best possible pixel-level detail is required, and the use of JPEG when extensive post-processing would be time-prohibitive.

Dynamic Range

While we did not attempt to quantify the K-S2's dynamic range, it has impressive shadow recovery capabilities as we have already seen.  The sample below further illustrates this.

Despite needing a +3EV adjustment, the camera still managed to capture plenty of detail at the pixel level with minimal noise.

100% crop of corrected image

Highlights can be a bit trickier and generally-speaking, there is much less room for recovery.  It is thus a better idea to underexpose than to overexpose.  For an example showing how much can be done when a portion of the area is blown out, download the RAW version of this image (from the Pentax K-S1):

Dynamic Range Sample - Click for RAW file