Pentax K-5 II / IIs Review

Aperture vs Resolution

Due to the onset of diffraction at slow apertures, compared to the K-5 II, the Pentax K-5 IIs only has an advantage at faster apertures, which means that premium lenses are generally the way to go if you opt to get a IIs.  Similarly, at high ISOs, the resolution advantage of the K-5 IIs fades due to noise and the resulting loss of detail (see our test chart photos on the previous page for examples of this).

Revisiting the moire example scene, let's take a closer look at two areas of the photo at different apertures.  For each area, we provide a sharpened and Original photo at F2.8, F5.6, and F13.  The ISO was fixed at 100 and the same 77mm lens was used on both cameras.  The JPEGs were developed from .DNG RAW files.

The sharpened versions were processed using Adobe Photoshop CS6's unsharp mask with a radius of 0.5 and amount of 100%.

Area 1 F2.8 - Original

K-5 II / K-5:

K-5 IIs:

Area 1 F2.8 - Sharpened

K-5 II / K-5:

K-5 IIs:

Area 1 F5.6 - Original

K-5 II / K-5:

K-5 IIs:

Area 1 F5.6 - Sharpened

K-5 II / K-5:

K-5 IIs:

Area 1 F13 - Original

K-5 II / K-5:

K-5 IIs:

Area 1 F13 - Sharpened

K-5 II / K-5:

K-5 IIs:

Area 2 F2.8 - Original

K-5 II / K-5:

K-5 IIs:

Area 2 F2.8 - Sharpened

K-5 II / K-5:

K-5 IIs:

Area 2 F5.6 - Original

K-5 II / K-5:

K-5 IIs:

Area 2 F5.6 - Sharpened

K-5 II / K-5:

K-5 IIs:

Area 2 F13 - Original

K-5 II / K-5:

K-5 IIs:

Area 2 F13 - Sharpened

K-5 II / K-5:

K-5 IIs:

Among the apertures tested, the K-5 IIs had a significant advantage at F2.8 and F5.6.  At F13, however, the final product differs very little between the K-5 II and IIs.

From these tests, it is clear that the K-5 IIs can in fact have a higher effective resolution than the K-5 II thanks to the lack of blur normally caused by the antialiasing filter.  Thus, each pixel on its sensor can deliver a reading largely unaffected by the pixels around it. There is a chance of seeing false color and moire patterns as a result, however, as we've alredy mentioned.

Also note that the moire in the first area disappears at F13.  Regarding the fringing, while the K-5 IIs seems more tolerant to it overall, in these photos it's likely being caused by changes in the sun's position between shots.  This test was repeated on two separate occasions and the same results were reproduced (save the fringing), to ensure accuracy.