The blurb for this "designed exclusively for digital" lens http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3301&navigator=6 offer "super wide-angle photography and it is a very powerful tool for indoor shooting and landscape photography with APS-C size image sensors of digital SLR cameras". Those sensors are around 25.1 × 16.7 mm, I think. It further states that "Vignetting will occur if the lens is used with digital cameras with image sensors larger than APS-C size or 35mm SLR cameras" My K10D uses a 23.5 X 15.7 sensor, so I thought I should be able to get nearly the full field of view (a full 10-20mm equivalent), yet when I questioned Sigma, they said I'd be subject to the 1.5 crop factor, making it a 15-30mm equivalent. If it will vignett on a 35mm, and is made for an APS-C sensor, aren't they mistaken when they told me the crop factor applies? If not, I'm really missing something.