Pentax K-3 Review
For our daytime high-ISO tests, we photographed the scene below at every ISO setting between ISO 100 (the minimum sensitivity) and ISO 51,200 (the maximum sensitivity) at one-stop increments. Note that unlike the K-5, the K-3 does not have an ISO 80 setting. The sample photos on this page are based on JPEG files with in-camera noise reduction set to Auto and all other settings left at their factory defaults.
Daytime high-ISO test scene
To enlarge and browse each series of photos, simple click on one of the thumbnails below and use your arrow keys or mouse scroll wheel to cycle through the gallery:
Our findings are the noise is relatively well-controlled up to ISO 3200. The amount of noise increases dramatically at ISO 6,400 in JPEG mode, anything above that should be avoided whenever possible, though if absolutely necessary you would probably be able to salvage an image shot at ISO 12,800 or even 25,600 at a lower resolution.
At ISO 100 the K-3's files are very clean, and the results at ISO 200 aren't much worse. We start to see noticeable noise in the shadows starting at ISO 400, but a significant loss in image quality doesn't occur until ISO 1600. We therefore conclude that ISO 100, 200, 400, and 800 are safe to use for everyday shooting. The fact that things become troublesome above that point is simply a current limitation of the APS-C system, though newer sensors have been getting better and better in this respect.