i have been offered an excellent condition sigma 100-300 f/4 ex apo lense from a friend of a friend - before pursue it how many versions of this lense have there been. The seller isn't sure whether it is the DG version but has there been any other versions that weren't DG i can't seem to find any info about this?
any help would be gratefully received 
I assumed US. Anyway, you can get new for good prices either from Kerso (check the buy and sell forum) or onestop-digital.com ... both reliable. I'd say £450 for a mint/boxed DG and £400 for the non-DG would be good prices. To get the last 10% of quality it likes a monopod, tripod or beanbag and it is big and heavy and handholding (for some) can be difficult due to shake.
