Pentax K-S2 Review

Auxilary Features

Finally, let's take a look at a few imaging features that make everything come together.

Stabilization

Every lens mounted on the Pentax K-S2 can be stabilized thanks to the in-body Shake Reduction (SR) system.  Formally advertised to compensate for up to 3.5 stops of camera shake, in practice SR enables successful hand-held photography with telephoto lenses or at extremely slow shutter speeds.  Gone are the days of blurry photos in low light.  Shake Reduction is without question one of the K-S2's most attractive features.

Autofocus lenses automatically transmit all the information the SR system needs to operate, but with manual lenses the camera will prompt you for a focal length at startup.  When using manual zooms, you must either enter the shortest focal length to avoid over-compensation, or update the focal length in the menu as you zoom.

AA Filter Simulator and Moire

While digital sensors without an anti-aliasing (AA) filter deliver increased sharpness, they are also prone to moire artifacts (i.e. false color patters) in subjects with fine, repeating patters such as buildings or textiles.  To counter this, the Pentax K-S2 has an innovative feature called the AA Filter Simulator, which is currently unique to Pentax bodies.  When enabled, this feature effectively suppresses moire by microscopically vibrating the sensor during exposure to simulate the effect of a hardware AA filter.  At the end of the day, you can thus get the best of both worlds with the K-S2: the sharpest photos possible without an AA filter, and moire-free images with the AA filter simulator enabled.

This feature works for both JPEG and RAW files and as we have previously demonstrated, it is quite effective.  The K-S2 also has a moire reduction option in its post-processing menu in case the AA filter was disabled.

Lens Corrections

When paired with Pentax DA, DA L, D FA, or FA Limited lenses, the K-S2's in-camera lens corrections can do away with optical imperfections that would otherwise show up in images or require manual adjustments.  Supported corrections include:

  • Vignetting (falloff / dark corners)
  • Geometric distortion
  • Diffraction (blur at small apertures)
  • Chromatic aberrations (fringing)

Let's take a look at how nicely the camera can suppress fringing at the pixel level:

http://www.pentaxforums.com/content/uploads/files/1/1458/CA_uncorr.jpg

http://www.pentaxforums.com/content/uploads/files/1/1458/CA_corr.jpg

Uncorrected (left) / Corrected (right)

Looking at the whole image, we can see the benefit of this as well as the remaining corrections (disregard any differences in exposure caused by RAW conversion):

Uncorrected
Corrected

However, lens corrections— especially distortion correction— can backfire at times when used with very sharp lenses.  In the 200% crop below, notice how details in the roof and fences vanish in the corrected image:

Uncorrected
Corrected

We therefore only recommend the use of distortion correction with consumer zoom lenses such as the 18-50mm kit lens, 18-135mm, etc.  If distortion is minor it's typically a better idea to correct it only if it adversely affects the final image.

As always, these corrections only apply to JPEG files, but they can also be applied to RAW files that are developed in-camera.


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