Trouble with an old lens

[zipzooka]

I have the 100d but i am having trouble using my old 70-210 lens.

Sometimes it will work fine, and then i take another shot with the same settings and it comes up with an error on the lcd about the contacts needing cleaning.

I never had any trouble when it was on my eos 30 film camera but since i have the 1000 i have been having troubles.

Not too sure on the exact model of the lens apart from its a Sigma 70-210 af

Markings on the body read as 1:3.5-4.5 apo macro. On the connection ring it has a white and a red dot where as my kit lens only has the white. Does this make a difference?

Any help on this would be really appreciated.

Thanks,
Aaron

 

[Jared]

It's the chip inside the lens i'm afraid. (I presume you have cleaned the contacts) My 100-300mm sigma had the exact same problem it's very anoying but there really is no solution other than using it with a tube as a closer up lens, this is what I do.