Resolution Chart Comparison (JPEG)
Images on this page are of our standard resolution chart which provides for measurement of resolution up to 4000 LPH (Lines Per Picture Height). A value of 20 equates to 2000 lines per picture height. For each camera we use the relevant prime lens (the same one we use for all the other tests in a particular review). The chart is shot at a full range of apertures and the sharpest image selected. Studio light, cameras set to aperture priority (optimum aperture selected), image parameters default. Exposure compensation set to deliver approximately 80% luminance in the white areas.
What we want to show here is how well the camera is able to resolve the detail in our standard test chart compared to the theoretical maximum resolution of the sensor, which for the charts we shoot is easy to work out - it's simply the number of vertical pixels (the chart shows the number of single lines per picture height, the theoretical limit is 1 line per pixel). Beyond this limit (when talking about line pairs usually referred to as the Nyquist frequency) the sensor cannot faithfully record image detail and aliasing occurs.
This limit is rarely attained, because the majority of sensors are fitted with anti-aliasing filters. Anti-aliasing filters are designed to reduce unpleasant moiré effects, but in doing so, they also reduce resolution (the relative strength and quality of these filters varies from camera to camera). In theory though, a sensor without an AA filter, when coupled with a 'perfect' lens, will deliver resolution equal to its Nyquist limit. Therefore, even though it may be effectively unattainable with normal equipment in normal shooting situations, an understanding of a sensor's theoretical limit provides a useful benchmark for best possible performance. Nyquist is indicated in these crops with a red line.
Note that while we usually compare both JPEG and Raw on the same page, here we've put just JPEG from both the K-5 II and K-5 IIS to compare the results with and without a low-pass filter. Look to the next page to compare Raw images from both cameras.
|K-5 II (4928 x 3264) 9.1MB||K-5 IIS (4928 x 3264) 8.7MB|
|K-5 II||K-5 IIS|
To find the two cameras' optimal resolutions, we shot with the 50mm F2.8 Macro lens and judged F5.6 to be sharper than other settings. Compared JPEG to JPEG, there's a slight difference between the K-5 II and K-5 IIS, with the former offering more apparent resolution across the range of possible interpretations - though we'd call maximum 'real' resolution at about 2100LPH - but the K-5 IIS delivers crisper results, resolving nearer to 2200LPH . Color error or moiré appear in the K-5 IIS's rendering more than the K-5 II, however, which is an important factor to consider, as it joins the extra sharpness along the way to 1900LPH, while the low-pass filter of the K-5 II avoids the effect by 2100 lines.
|Pentax - K-S1 Digital SLR Camera with DA L 18-55mm Lens, 20MP, LED Indicator Grip, PRIME M II Processor, 5.4 Frames Continuous Shooting, Full 1080p HD Video, Sunset Orange||$646.95|