Pentax K-5 II High ISO NR
Pentax K-5 II High ISO Noise Reduction
Like other Pentax models, the K-5 II offers an unusually flexible amount of control over noise reduction applied to its JPEGs. In addition to "Auto", you can adjust how much NR is applied ("Off", "Low", "Medium" or "High") at all ISOs, or you can select "Custom" which allows you to choose from the same four options at each ISO sensitivity setting in whole EV increments. That is, if you enable 1/3 EV ISO steps, you get one NR setting for ISO 100, 125, and 160, another for ISO 200, 250, and 320, etc. The same applies for 1/2 EV ISO steps, but with only two sensitivities sharing each setting (ie. ISO 100 and 140 share a setting, ISO 200 and 280 share one, etc.). Kudos to Pentax for providing such excellent control over noise reduction for JPEGs.
See for yourself how the Pentax K-5 II's "Medium", "Low" and "Off" High ISO NR settings compare to RAW without noise reduction under daylight-balanced lighting. (Note that these RAW images have no sharpening applied, so they look softer than camera JPEGs at low ISOs.) Click on any of the crops below to see the corresponding full-sized image.
As you can see, the Pentax K-5 II applies high ISO noise reduction already at its lowest sensitivity of ISO 80. Also notice the "Off" setting clearly does not eliminate noise processing altogether (especially chroma noise suppression above ISO 1600), but it does leave the most fine/subtle subject detail in JPEGs. We can also see by the blotchy appearance of chroma noise that some subtle noise suppression is likely being applied to RAW files above ISO 1600. Unfortunately noise reduction in the K-5 II's RAW files at high ISOs can't be disabled, as we've seen in previous Pentax DSLRs. Still, shooting in RAW mode will give you maximum detail and control despite the K-5 II's very flexible noise reduction settings.