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sigma 90mm f2.8 macro

Started Nov 28, 2009 | Discussions thread
Steve Balcombe Forum Pro • Posts: 15,582
Re: sigma 90mm f2.8 macro

ken wrote:

well it dosnt say di on it so i guess the older one

I think Jay (like Gautam) has assumed you meant the Tamron 90mm macro, because it's the only 90 mm macro lens currently available. I'm saying this because the DI question refers to Tamron, not Sigma.

However I suspect you do mean the long-discontinued Sigma 90mm macro and haven't made a mistake. If so, I'm afraid most (possibly all?) Sigma lenses of that vintage don't work correctly on Canon DSLRs.

The reason apparently is that Sigma doesn't licence the communication protocols in Canon's EOS technology, instead it reverse-engineers them. Reverse engineering is a jargon term for educated guesswork - this means that while Canon has ensured backward compatibility with every EF lens ever made, there can be no such assurance with Sigma. As Gautam explained, Sigma used to replace the electronics in their lenses to make them compatible with present-day cameras, but I haven't read of anyone having that done for a long time.

Knowing this doesn't put me off buying Sigma lenses by the way - I have two - but it is important to be aware of it when buying used, or banking on using an old lens you have left over from a film camera. And buying Canon is not a guarantee of backward compatibility - all the Speedlite flashes prior to the EX series don't work with DSLRs.

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