That crazy ISO number is native, so it uses the electronic gain, rather than software to attain that sensitivity (unlike with extended ISOs). Pentax didn't supply any samples in the upper ranges, but images at ISO 25,600 and 51,200 look decent.
The K-1 Mark II also has a new pixel shifting system called Pixel Shift Resolution System II. Like similar systems from Sony and others, it can capture four burst photos and marry them into "super-high-resolution images," Pentax parent Ricoh said. The new system now captures RGB color with each pixel however, allowing for "significantly finer details and truer colors" than other DSLRs, according to the company.
The pixel shift system now allows handheld shooting in concert with the five-axis stabilization. "The system works together with the camera's shake-reducing mechanism by synthesizing the composite images while detecting the slight fluctuations of the subject's position during the capture process," Ricoh explained.
Other features remain unchanged, including the 36.4-megapixel sensor with anti-alias-free filter, 5-axis image stabilization, 3.2-inch tiltable (but not flippable) screen, AI-based real-time scene analysis, 33 autofocus sensors, dual SD card slots (UHS-1 only), 4.4 fps burst speeds and, unfortunately, 1080p 30 fps video.
There's one advantage to Pentax not having changed the new model much. If you bought the original K-1, you can pay $550 and Ricoh will upgrade the circuit board to the one on the K-1 Mark II, giving you all the features of the new model. You'll even get a cosmetic upgrade with the new K-1 Mark II logo. The new model arrives in stores in April for $2,000, or $2,400 in a bundle with the Pentax-D FA 28-105 f/3.5-5.6 ED DC WR zoom lens.