Sigma 4/3 18-50 Lens Problem

[Roger.Tomblin@vodafone.ne]

I have a Sigma 18-50 Lens which is exhibiting a strange fault. All pictures taken with this lens are completely over exposed as if it is not stopping down, now here is the rub. I have tried this lens on my e300, 500 and 510 all exhibit the same fault, Took the lens to LCE in Plymouth who tried it on one of their 510 bodies and pictures were perfect. Showed them the problem first hand on my bodies, so they sent the lens back to Sgma back in November. Sigma after much chasing returned the "Repaired" lens today Got the lens back today from LCE (Tried it in the shop on their 510 and it was fine) Guess what, got home tried it on my 510,500 and 300 and it still dosn't work. All my bodies are at latest Firmware standard. I have 2 other Sigma lenses 55-200 and 135-400 and they work perfectly Anybody out there seen a similar problem.

[Photocracy]

Re: Sigma 4/3 18-50 Lens Problem

What a puzzle!

Taking the facts, one by one;

The suspect Sigma works on LCE's body - therefore, it does work.

Your other Sigma lenses work on all three of your bodies, therefore, your three bodies definitely work.

The suspect Sigma (which we have established works) does not work properly on any of your three bodies.

The logical conclusion from this is that there is some interference in the interface beween the suspect Sigma and your three bodies which does not occur on the 4th (LCE) body.

What could the difference be? My first suggestion would be to carefully clean the contacts on both the suspect Sigma and your three bodies. I know this cured my auto focussing irrationalities. It has to be somewhere here, where the lens to body communication is being interefered with in some very slight way which does not occur on the LCE body. As you say, the iris is probably not stopping down and one of those contacts must relate to this. Try the cleaning trick, particularly on the lens contacts, and see what happens. I rubbed them with a lens cloth while holding the body and, in turn, the lens face down to stop debris going in. If that fails, come back and we'll try and enlist more help.

[dlinney]

Re: Sigma 4/3 18-50 Lens Problem

One possible thought: is LCE's body at latest firmware level? If not it could be a problem between the Sigma lens and the latest firmware levels? Can LCE try it on another body?

[Roger.Tomblin@vodafone.ne]

Re: Sigma 4/3 18-50 Lens Problem

Thanks for the response Have tried cleaning the contacts before I sent it back, have spoken with Sigma today and also returned the Lens to them, they are puzzled although we did discuss the possibility of a firmware and compatibility issue.

[Roger.Tomblin@vodafone.ne]

Re: Sigma 4/3 18-50 Lens Problem

Thanks for the response.Have discussed the possibility of a firmware issue with Sigma and returned the lens to them, They are going to look into the firmware and come back to me will keep you posted on progress

[Roger.Tomblin@vodafone.ne]

Re: Sigma 4/3 18-50 Lens Problem

Now a happy bunny, After returning lens and long discussions with the Sigma support people they have now replaced the Lens for a new one and it works fine on all the my bodies and the LCE body.