Canon 1.4x II extender

Started 3 months ago | Discussions thread
Dave Veteran Member • Posts: 5,583
Re: Canon 1.4x II extender

John Pane wrote:

Dave wrote:

John Pane wrote:

james djg wrote:

Does anyone know if the Canon 1.4x II extender is 100% compatible with the Canon 5DS and the Canon 400mm f5.6L lens?

It is optically compatible but it may not autofocus. Canon says:

Effective aperture is reduced by one f-stop; autofocus is possible on any EOS DSLR when combined with a lens having an f/4 or faster maximum aperture.

It can be used with fixed focal length lenses 135mm and longer (except the 135mm f/2.8 Softfocus lens), and the following zoom lenses: EF 70-200 f/2.8L, 70-200 f/2.8L IS, 70-200 f/4.0L, 70-200 f/4.0L IS USM, and 100-400 f/4.5-5.6L IS.

Is that camera-related? My 80D's manual places the 400mm f/5.6 and 1.4x extender combination in group H (center AF point only) for all three versions of the extender.

It also states "if the maximum aperture is slower than f/5.6, focus may not be achieved with AF when shooting low-contrast or low-light subjects". Further, "if the maximum aperture is slower than f/8, AF is not possible during viewfinder shooting".

Yes. Actually it looks like some cameras (including 5DS) can autofocus at f/8, which means a f/5.6 lens + 1.4x extender should support AF.

I wish I remembered where I read it, but I believe version III only offers improved performance over version II when used with certain newer lenses.

 Dave's gear list:Dave's gear list
Canon EOS 80D Canon EF 135mm F2L USM Canon EF-S 17-55mm f/2.8 IS USM Canon EF 100mm F2.8L Macro IS USM Canon EF 70-300mm f/4-5.6L IS USM +10 more
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