Sigma 10 - 20mm lens softness problems

Well it seems there's a serious problem with my Sigma wide angle lens! I was examining some recent photo's when I noticed that the left side of the images looked soft, particularly if there was dense foliage there. I don't know how long the lens has been like this because if there is not a lot of detail on the left side it is actually hard to detect. Below are a sample from the left side and the right side of the same image, shot at 10mm, F16 with the focus point set at 4 feet so everything in the frame from about 2 feet and back should be in sharp focus. Spot the obvious softness on the left!














I googled the subject last night and discovered that this is actually a very common problem on this particular lens called 'decentering', mostly affecting the right side and on brand new lenses too! How the hell does something like this get past Sigma QC, especially if it is happening as often people are claiming?

My particular lens is actually around 14 months old now so it is well past the warranty which means I'll have to cough up for the repair. I've emailed Sigma support for a quote and the turnaround time is usually about 2-3 weeks, so in the meantime I'll dig out my Canon 100mm macro lens as I've been meaning to capture some ideas that I have.

Cheers for now.