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Kenko DGX x1.4 extender

Hi there

I have recently upgraded to 1Dx and therefore passed on my old 1D4 to my wife who has been using 7D w/400mm 5.6.

Without he 1.6 crop factor of the 7D she has been used to, she is finding the 1.3 crop factor of 1D4 leaving her a little short of focal length.  I managed to find an DGX x1.4 from the Macro days of shooting butterflies and find that it produce very poor picture quality .. and is about 3 stops darker.

BUT >> when used with my 1Dx and 800mm 5.6, not only is the picture quality is pretty decent (having only tested indoors and in dark conditions without putting the images onto a big computer screen to compare) .. BUT all AF points are working .. (when used with a Canon x1.4 III) only the centre cross 4 point is available ..

The question is .. has anyone tried the Kenko extender with 400mm 5.6 and a 1D4?  And if so, how have you found the performance?

Also, I have heard people use tape to cover up the 3 contact points on an original Canon extender to trick the camera in giving all AF points .. has anyone tried this method?

thanks in advance ..

When I brought the second-hand cannon 1.4X extender, the salesman helped to cover the 3 pins and the AF works (I am using 7D+100-400mm f5.6). For 7D for AF, the f should be below 7, so when I use 400mm with 1.4X extender, the effective f is 7.84, so do not have AF. Although, AF works but the speed is too slow for capturing flying birds and practically it does not have AF.

I have had a lot of success using the Canon 7D and 300mm f4 lens with TWO 1.4x extenders. One is a Canon and the other a Kenko it focus ok on all points

[url]http://www.flickr.com/photos/jingbar/8570309293/in/photostream/lightbox/[/url]

Bob

Thanks Bob for your information. But f4 x 1.4 x 1.4 = 7.84 which is the same as my 5.6 x 1.4, so you mean you can AF with your set of equipment?

Yes it autofocusses on all point but not spot focus

It doesn't appear to work with my Canon 400mm F5.6 but the Canon 1.4x does work with the correct pins taped over.

[[i] Last edited by tbob at 3/04/2013 19:51 [/i]]

Thanks once again for sharing