Of course I know that Canon 'doesn't mind' when third party lenses have to be rechipped (in fact I think they will
enjoy it from a commercial point of view)
But since all Canon lenses still work on a 20D it's a fault in the back-enginering capabilities of the Sigma
techniciens. Marketing wise they scream it's compatible, technicaly it's not ....
I'm not sure it's fair to say that it's a fault of Sigma's "back-enginering capabilities".
It seems obvious that the Camera and Lens needs to communicate to each other any special needs that they have (i.e. unusually high current consumption, IS, Limited available power, etc.). If a particular body can't supply enough current, the lens' focusing motor may have to operate at reduced speed.
I always assumed that the bodies have a database of lenses that require special treatment. Similarly, new lenses have a database of bodies that require special treatment (i.e. on Body X, the lens should identify itself as Y and the focus motor needs to run slowly).
When you put a lens on a body, one or the other might need a database entry explaining how the two should interact.
I expect that Canon authorized equipment only has entries for other Canon authorized equipment. I would be surprised if there were entries for unauthorized/unlicensed equipment.
The re-chipping issue might just be that Canon neglected to put third-party lens information into your new camera, so the lens manufacturer needs to re-chip the lens to add information about the new body.
The above is just speculation on my part. There are many reasons why new bodies may need to be rechipped. it could be due to reverse-engineering mistles on Sigma's part, or it just may be a design decision on Canon's part.
It isn't fair to try to place the blame on any one party without more information on how Canon's proprietary system works.
-Michael Fryd * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
