On Sat, 16 Aug 2003 10:02:22 +0900, Jim Davis wrote: >"Gary Fisher" <[EMAIL PROTECTED]> wrote/replied to: > >> >>I would think that should be ok. Both the Canon and the Sigma extenders have protruding front elements. > >Wow, I didn't know that. Is this a special Sigma extender to go with >their pro lenses or something. I can't believe all >Sigma extenders would not fit anything but a Sigma Pro lens or a Canon >L lens. > >Interesting that Kenko actually makes a 3X extender in their new >lineup or Pro extenders. > >I want to get a 3rd party 1.4 or 1.5 extender. But I want it to work >with AF on my 100-400L IS. Does anyone know if the new Pro Kenko >extenders will do this, or do they report the proper aperture? > >I don't mind to get an older Kenko as they are quite excellent, but I >would like the best possible for the situation. The Canon is out >obviously, cause it won't AF at all. > >What about a Sigma? > > > >Jim Davis >Nature Photography >http://www.kjsl.com/~jbdavis/ >*
Hi I came across a note about covering 3 contacts on the 100-400 that will allow it to attempt auto-focus with Canon extenders. These 3 contacts are not included on non-Canon extenders. I tried this trick using a Canon 1.4x extender, Elan 7e and 100-400L. The camera body/meter didn't realize there was an extender involved and thought I was using a 560mm/f5.6 lens. The only problem was auto-focusing, it would only work with the centre AF point on brightly lit high-contrast subjects. Otherwise the AF would hunt around trying to focus. I haven't tried non-Canon extenders, but it would be interesting to hear how auto-focus is affected. Rob Chandler www.rcp.ca * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
