i would like to know what compatibility problem would occur if i fit a third party lens onto an EOS? currently,i am using a sigma lens with EOS 300,but i don't have any problem.

-- legnum (legnum212@email.com), November 09, 2001

Answers

Many third-party lenses have compatibility problems with many bodies. Many do not.

The general guideline is that older lenses are sometimes incompatible with newer bodies. If you have a particular lens that works with an EOS 300, chances are extremely good that it will work with older bodies, but there's a possibility that it may not work with some newer bodies. If you have a particular lens and are considering upgrading your body, it would be wise to check with the lens' manufacturer first and make sure there won't be any compatibility problems. (In many cases, Sigma will upgrade the lens' electronics for free to make it compatible with a newer body.)

-- Steve Dunn (steved@ussinc.com), November 09, 2001.

Legnum, if you are asking what the symptoms would be, there is a whole list of things that people have reported. No autofocus or erratic autofocus, lens aperture will stick open or closed, mirror stays up, "bc" flashes on your LCD even with a new battery, camera freezes, and many more.

Sigma isn't the only manufacturer with the problem, I have heard of several Tokina lenses and one Tamron among others. And it doesn't just effect Canon cameras either. A lot of existing lenses won't work with the new Minolta 7. Tamron sales reps say this isn't possible with their lenses because they have a deal with Canon that lets them have all the specs on the Canon EF mount. So maybe the report about the Tamron was just a problem with that particular lens. I don't know.

-- Jim Strutz (j.strutz@gci.net), November 09, 2001.

I'm new at this so my experience should be seen through that lens, but my Elan 7 EOS works great with 2 Sigmas, one is the 50-500mm and the other is the 100mm Macro.

-- venado (deertex@swbell.net), November 10, 2001.