I bought a Sigma 100-300mm f4 from another PF member but it arrived with the rear lens cap off and damage to the aperture mechanism which may have been from shipping (it had also been used on a NEX). It was effectively a wide-open F4 lens but according to all the reviews this was not a problem for the lens.

I finally sent the lens in to Tudortech who are the South African agents for Sigma (Belkin, Olympus and a few others) to see if it could be repaired. They said that if parts were required they would probably not be able to repair it. I was not holding out much hope as the lens was discontinued several years ago. The lens was handed in at the Johannesburg office, couriered to Cape Town where they replaced the kinked spring, and freed up the aperture blades. It was then couriered back to Johannesburg. The whole process took a week exactly. Unfortunately there was now a problem with the aperture not opening up fully so it went back again and they fixed that. The lens now has a working aperture, but reads a 1/2 stop lower than it should on manual which I can live with. It should be ok on Auto. I now have a fully functioning stunning zoom lens still at a good price including the repair costs.

I was totally amazed at the swift and reasonably priced service from Tudortech. Many thanks to Palesa, Carrie-Ann and Greg at Tudortech. It's nice to know that there are companies out there who deliver good service, and especially for us Pentax users.

[KevinR]

Good to know this about Sigma agents in SA. Thanks for posting, and enjoy that 100-300 f/4. By all accounts a stunning lens.