hrm, how come no one reply, i must have missed it
if you look at the lens test on this one, very hard to correct
you see, only the corners are very affected, if you correct will be problematic
if you see this site here by ken rockwell, you will also observe that at 10mm, it is very hard to correct in photoshop because of this unique characteristic.
i would not worry too much about it , just do not place important things in the corners, shoot with a spirit level, you will minimise such problems
the best software I know of for correcting the Sigma 10-20 (I own this lens as well) is the DxO Optics Pro... the transformation they apply to the image is specific to the lens, camera, aperture, focal length, etc. so the adjustments would be better than tools which are not so specific...
Thanks Pal. BTW, what do you mean by 'shoot with a spirit level'? Is it that green liquid that indicates the level of your tripod?
I use PTlens for lensdistortion, it's a cheap 1 time buy and lifelong free updates.
the best software I know of for correcting the Sigma 10-20 (I own this lens as well) is the DxO Optics Pro... the transformation they apply to the image is specific to the lens, camera, aperture, focal length, etc. so the adjustments would be better than tools which are not so specific...
there are two packages, one that only covers consumer and prosumer models, DxO Optics Pro Standard, and one that covers all models, DxO Optics Pro Elite... but in either case, all lens modules within their particular category are available for free download according to the categories (i.e. people who have the "Standard" package can download all lens modules within this package, and those with "Elite" can download everything) including ones added in future updates...DxO Optics has the different lens characteristics as functions built into it, and not all the lenses are available initially. You have to buy them separately IIRC.
there are two packages, one that only covers consumer and prosumer models, DxO Optics Pro Standard, and one that covers all models, DxO Optics Pro Elite... but in either case, all lens modules within their particular category are available for free download according to the categories (i.e. people who have the "Standard" package can download all lens modules within this package, and those with "Elite" can download everything) including ones added in future updates...