Do they use it as a fisheye or do they use a Photoshop plugin / image editing software (ala Fisheye-Hemi or DxO) to correct the image back to rectilinear images?
I'm thinking about this lens to replace my Sigma 12-24mm but I am after linear wide angle lens, not a fisheye - I was wondering how much image quality would be lost during the conversion back to a linear image.
I really like this piece of glass. I use it on the 5DmkII & 1DmkIV. Of course I don't use this lens on daily base, but it sure gives me the opportunity to create something special. Sometimes I edit the pictures sometimes I leave as circular as possible.