I have an issue with noise, and am sure that it is present even at 100 ISO. At 250 ISO it is evident without doubt in grey skies at 100% crop. 800 ISO and above is unusable for landscapes, in fact you can see it at normal PC screen size, let alone 100%. Does anyone else have the same issue, or is it faulty? You can see the effect on some of my images in flickr if this helps