The Korean Popco.net strikes again, here is the quick side-by-side shootout!
http://www.popco.net/zboard/zboard.php?id=dica_forum_pentax&page=1&sn1=&divpage=3&sn=off&ss=on&sc=on&select_arrange=headnum&desc=asc&no=14223
(in Korean)
Well, there is no surprise, the ISO 12800 of the K-5 is even better than the ISO 6400 of the K-7. But as we all knew, higher ISOs of the K-7 actually, suck! Not even to mention the obviously better colour accuracy and more favourable colour response of the K-5 (and sensor) that can be seen.
Well, the hard fact is that the culprit should be the sensor. So it's not solely the fault of Pentax, except that they chose the sensor wrongly for the K-7! For a very wrong sensor.. :-(
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Korean Popco.net K-5 Hands-on Preview