Fault query

My 20D / Sigma 500mm combo has recently developed a fault and I was wondering if anyone on here can offer any advice. When the 500 is mounted on the 20D body I cannot change any settings. When a button is pressed (as in the iso button/ af button/info button etc) what normally happens is the LCD shows the setting screen for long enough to change settings. However on mine it won't stay on to allow things to be changed, it just flicks on when pressed and immediately goes off. I have tried the body with several other lenses and even with extension tubes etc and there is no problem with any of them. I have tried the 500 with my other body and again no problem so it appears to be specific to the 20D/500 combination. I've tried cleaning the contacts on both the lens and the body but that hasn't made any difference. Any thoughts?

Hi Robert.
I had a similar problem with a new Sigma 300 2.8 and a D30 in 2003. They just would not play together, but each would work fine with other cameras/lenses. In my case it turned out a mechanical setting in the lense was almost out of tolerance. Camera and lense talk to each other and if everything is not within specified limits they will refuse to do anything - to avoid damage. So I was just unlucky that the tolerance on my D30 was out the wrong way - and put the combination out of spec.

The tech at Sigma fixed it very quickly, and it has been fine ever since.

Hope this helps - John

Thanks for that John, I'll get in touch with them.

Robert

Problem now solved. Turned out to be a simple case of a little extra cleaning of the contacts with a pencil eraser as suggested by Jim DeWitt on the General Discussion Forum.