Originally posted by Swapnil Correctly said. Expanding ISO to 100 will reduce the DR. Lowest ISO in K-r and K-x is 200 whereas ISO 12800 is totally not usable.
Try taking few sample shots to set high ISO limit
Whats wrong with 12800 ?
http://i448.photobucket.com/albums/qq204/TGPhotography/High%20ISO%20Shots/2011Jude0842-2.jpg
The link is to a shot I took as an experiment to see how bad it is at 12800 and I was shocked at how GOOD it was .
Exif should be intact but in case Photobucket has removed it, details are.
Camera ; Pentax KR
Lens; Sigma 28-105 F2.8 zoom
Mode; RAW
ISO 12800
F Stop; F/8
Speed; 1/13th sec hand held
Focal Length 63mm
No Flash
Metering ; Centre weighted
All I have done is convert to jpeg to upload to Photobucket because it will not take the RAW file, so if anything it should have lost some detail.
This is the same photo after 1 pass of Topaz Denoise RAW Medium and obviously resized to post here.
As for the 100 Vs 200 ISO, 100 wins hands down, If I could afford a K5 I would be using 80 ISO.
Using the same lens as I took this shot which is a film not Digital era lens, on some shots especially landscapes the colours are not as vivid at ISO200 as they are at ISO100.