Pentax K-30 High ISO NR
Pentax K-30 High ISO Noise Reduction
Like other Pentax models, the K-30 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 to providing such excellent control over noise reduction for JPEGs, though as you can see from the crops below, the "Off" setting does not disable noise reduction as the name would imply.
See for yourself how the Pentax K-30's four noise reduction levels work under daylight-balanced lighting. Click on any of the crops below to see the corresponding full-sized image.
As you can see, the Pentax K-30 applies high ISO noise reduction already at ISO 100, and all settings are fairly aggressive in the red channel. Also notice the "Off" setting clearly does not eliminate noise processing altogether, especially in the red channel, but it does leave the most fine/subtle subject detail. Shooting raw however will of course give you maximum detail and control.