Your Sigma lens delivers excellent results. I just have taken a look at the specs; the Sigma 10-20 mm DC does not work with FF cams, in addition, the angle covered by the 12-24 mm DG is considerably wider, 122 degrees instead of 102, so for the D700 or the 5D, it is the better choice IMHO.
-Gerald
Yes Rod this is a pretty impressive lens for the price and I strongly recommend it for full frame and crop frame users, especially for its superwide quality. This shot has no cropping or pp corrections except RAW processing and a bit of levels and sharpening. With other zooms I always correct for barrel/pincushion distortion in Photoshop but this lens rarely requires it, especially at the shortest focal lengths. Longer focal lengths are move complex. I always shoot with RAW + jpg nowadays, so I put the "unprocessed" jpg in Pending for your pleasure and amazement. You might want to rethink that Sigma 10-20. What's 2mm anyway? I used to think this was a chunky lens but not when compared to "L" zooms. Only a couple of quirks: rather exposed front element and no front filters - only proprietary rear filters. I bought the lens used without filters. -tv