If you intend to keep the lens for a long time and you see yourself moving to a FF camera in the future (2-3 years), then the Sigma 12-24 is the only option! Unless you take the Nikon or Canon 14mm primes. :dunno:
Regarding the distortion part, the percentage may seem small, but when you take buildings, it can be seen as some of the guys on the net seem to report. :think:
As for filters, well it is possible to make a suitable mount for filters for that lens, if you're willing to spend that kind of money. In fact based on rough estimates, the smallest filter size that can cover the 12mm breath would be 95mm with a suitable adapter. You certainly won't want to know how much a 95mm CPL filter costs though! :bigeyes::sweat:
Regarding the distortion part, the percentage may seem small, but when you take buildings, it can be seen as some of the guys on the net seem to report. :think:
As for filters, well it is possible to make a suitable mount for filters for that lens, if you're willing to spend that kind of money. In fact based on rough estimates, the smallest filter size that can cover the 12mm breath would be 95mm with a suitable adapter. You certainly won't want to know how much a 95mm CPL filter costs though! :bigeyes::sweat: