Canon 1.4x II extender

Started 4 months ago | Discussions thread
John Pane
John Pane Regular Member • Posts: 271
Re: Canon 1.4x II extender

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.

 John Pane's gear list:John Pane's gear list
Canon EOS R5 Canon RF 28-70mm F2L USM Canon RF 35mm F1.8 IS STM Macro Canon RF 70-200mm F2.8L IS USM Canon RF 85mm F1.2L USM +3 more
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