Originally posted by Adam You should be fine up to 6400 when processing raws, but yes, there's a big loss of detail at 1600 and again at 6400.
totally agree here. i was shooting a dance show last year with ISO as high as 3200 with my K-50 and kit lens (18-135) and got "acceptable" results once PP.
first photo is at ISO 3200 and 2nd one at ISO1600. i was a complete beginner then and was not familiar with RAW format. All photos were shot in JPEG and these 2 were also cropped.
sorry but no EXIF data in the 2nd pic since all data was removed from the photos that were taken for prints.
So considering this, with the k-3 being a far superior camera, i am sure that ISO 6400 is definitely possible, maybe even higher depending on the subject, colors, contrast etc etc.