Greetings, I recently noticed that many pictures that I took with my Canon 7D+Tamron 17-50 and include sky in the composition seem to have noise. By noise I mean that sky pixels' color seems to change abnormally. These pictures were taken with low ISO (100-200). I attach a 100% crop of one of those. Is this normal? I would like to point out that although I attached a jpg the same "noise" appears in raw images viewed in both DPP and Preview. Thanks in advance.