Pentax K20D High ISO Image Quality

The Pentax K20D offers four high-ISO noise-reduction settings, allowing you quite a bit of flexibility in choosing how you want to make the trade-off between subject detail and noise levels. Settings available are Off (default), Low ("Weakest"), Medium ("Weak") and High ("Strong"). See for yourself how the noise reduction works under daylight lighting. Click on any of the crops below to see the corresponding full-sized image.

Pentax K20D High ISO Noise Reduction Comparison Simulated Daylight
	High ISO Noise Reduction Setting
	HINR=Off	HINR=Low	HINR=Medium	HINR=High
I S O 8 0 0
	HINR=Off	HINR=Low	HINR=Medium	HINR=High
I S O 1 6 0 0
	HINR=Off	HINR=Low	HINR=Medium	HINR=High
I S O 3 2 0 0
	HINR=Off	HINR=Low	HINR=Medium	HINR=High
I S O 6 4 0 0

The above crops show the effects of the four levels of High ISO Noise Reduction available on the Pentax K20D. It's rather unusual that the default setting is Off. Most digital SLRs default to a medium setting. Pentax doesn't say, but High ISO Noise Reduction doesn't seem to kick in until above ISO 800. Interestingly, the setting has little effect at ISO 6,400.

To see what the sensor is actually delivering in terms of detail and noise, we've converted K20D ISO 800 to 3,200 DNG files using dcraw, a raw converter that does not apply any noise reduction or sharpening. See below for crops and click on the images to load the full resolution converted file.

Pentax K20D High ISO Noise Comparison from RAW Simulated Daylight
DNG RAW files converted with dcraw, no NR, no sharpening
ISO 800	ISO 1,600	ISO 3,200	ISO 6,400

Though the K20D's RAW images are quite soft without any sharpening, noise is well controlled, with surprisingly little at ISOs 800 and 1,600. There's quite a bit more noise (especially chroma) at ISO 3,200 and 6,400, but we think you could do much better than the in-camera JPEGs by shooting RAW and post-processing using a good noise reduction program such as Neat Image, Noiseware, or Noise Ninja.