One of the most exciting new features of the EOS-1D X Mark II is the ability to autofocus through the viewfinder at its maximum effective aperture of f / 8. For the first time ever, a Canon EOS DSLR can autofocus - with selected combinations of EF telephoto or zoom and Canon EF version III tele-extender - at effective maximum apertures of f / 8.

Many seasoned Canon EOS photographers have long asked for autofocus capability with lenses darker than f / 5,6, especially for nature, wildlife and sports photographers. Any photographer who usually uses long telephoto lenses and wants to expand their capabilities with the Canon Extender might want the same capabilities.

Typical real-life examples would be attaching a 2x extender to an f / 4 lens such as the EF 500mm f / 4L IS II. Or by attaching a 1,4x extender to an f / 5,6 lens (such as an EF 400mm f / 5,6L). In any case, the widest effective aperture of the lens + extender will be f / 8.

Canon first responded to these requests for f / 8 autofocus compatibility with the release of the EOS 3 (35mm film camera), in 1998, which allowed autofocus with lenses from f / 5,6 to f / 8 only at the center point autofocus. Subsequent attempts so far have also included autofocusing at f / 8 only at the center AF point or, in some cases, allowing the four surrounding AF points to provide an extension of the AF point around it.

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Until now, autofocusing at f / 8 - if the Canon EOS camera even offered this feature - meant autofocusing only at the center AF point when the effective maximum aperture of the lens was less than f / 5,6. Some cameras, such as the EOS 5D Mark III, will allow users to enlarge the size of this center AF point by using four single-line “sub” AF points surrounding the main AF point.

 

AF at f / 8 at all 61 points!

The all-new AF sensor and AF optics design on the EOS-1D X Mark II is a game changer. In response to urgent requests from professionals and serious enthusiasts, Canon engineers have tried to redefine autofocus capabilities at f / 8 without sacrificing high-precision autofocus when using fast lenses.

Depending on the lens and Canon telescopic extender used, autofocusing with a maximum effective aperture of f / 5,6 to f / 8 with 61 AF points can now be achieved! This surpasses viewfinder AF on any previous Canon EOS DSLR and opens up new possibilities for photographers looking to work with Canon EF tele extenders and compatible telephoto lenses.

When a compatible lens + extender combination allows f / 8 AF at all 61 AF points, the center 27 points retain cross-type AF coverage - meaning each point can read information and details both horizontally and vertically.

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With the EOS-1D X Mark II and the right combination of EF lens and telescopic extender version III, autofocus is possible at all 61 AF points. And the AF points outlined here in bold will provide cross-type coverage, which means they're more likely to "capture" subjects with little detail or contrast.

 

Full compatibility with all 61 AF points on the EOS-1D X Mark II requires the use of Canon's teleextender version III in conjunction with Canon's dedicated lenses. With older Canon EF tele-extenders and / or other Canon EF extender-compatible lenses, fewer AF points are available if the extender makes the effective maximum aperture less than f / 5,6. But even here, in most cases, more AF points are available than on any previous EOS SLR.

Version III lenses and telescopic extenders providing f / 8 AF at all 61 AF points

The following lenses, used with these Canon Version III teleextenders, will enable the EOS-1D X Mark II to autofocus at all 61 AF points with an effective widest aperture smaller than f / 5,6:

  • EF 100-400mm f / 4,5-5,6L IS USM  (lenses versions I and II)  + EF 1,4x III
  • EF 200-400mm f / 4L IS USM with integrated lens 1,4x + EF 1,4x III
  • EF 200-400mm f / 4L IS USM + EF 2x III
  • EF 400mm f / 5,6L USM + EF 1,4x III
  • EF 400mm f / 4 DO IS USM  (lens options I and II)  + EF 2x III
  • EF 500mm f / 4L IS USM  (lens options I and II)  + EF 2x III
  • EF 500mm f / 4.5L USM + EF 1.4x III
  • EF 600mm f / 4L  (all lens versions)  + EF 2x III

f / 8 AF at 13 different AF points

When the current 2x Version III Extenders are combined with some other Canon f / 4 telephoto lenses that provide an effective maximum aperture of f / 8, the EOS-1D X Mark II allows up to 13 AF points to be used. Of course, while not offering full AF flexibility across all 61 points, it still significantly expands the focusing options over previous EOS DSLRs that limited f / 8 autofocus to only the center point.

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The following f / 4 lenses allow AF to be used with a maximum effective aperture of f / 8 when used with Canon 2x Tele Extenders Version III. AF points can be individually selected, manually moved between compatible locations, and AF point expansion is possible at the center AF point. And the center AF point provides cross-type AF coverage with these lens and extender combinations.

 

  • EF 300mm f / 4L USM  (IS and without stabilization)  + EF 2x III
  • EF 70-200mm f / 4L USM  (IS and without IS)  + EF 2x III

AF f / 8 with old Canon telescopic extenders - 9 AF points

For technical reasons, Canon's latest EF Version III Extenders (1,4x and 2x) are paired with the EOS-1D X Mark II to provide the ultimate in autofocusing at f / 8. But Canon engineers don't ignore the legions of Canon users who may often use older Canon extenders, either version II or the original EF 1.4x and 2x extenders.

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Even with older Canon tele-extenders, autofocusing is possible at a maximum effective aperture of f / 8 at nine different AF points.

 

The EOS-1D X Mark II allows f / 8 AF at nine different AF points - with cross-type AF at the center AF point - with any of the following combinations of lens and older extender:

  • EF 70-200mm f / 4L USM  (IS and non-IS versions)  + EF 2x I and II
  • EF 100-400mm f / 4.5-5.6L IS USM  (lens options I and II)  + EF 1.4x I and II
  • EF 200-400mm f / 4L IS USM (with built-in lens 1,4x  )  + EF 1,4x I and II
  • EF 200-400mm f / 4L IS USM + EF 2x I and II
  • EF 300mm f / 4L USM  (IS and without IS)  + EF 2x I and II
  • EF 400mm f / 5.6L USM + EF 1.4x I and II
  • EF 400mm f / 4 DO IS USM  (lens options I and II)  + EF 2x I and II
  • EF 500mm f / 4L IS USM  (lens options I and II)  + EF 2x I and II
  • EF 500mm f / 4.5L USM + EF 1.4x I and II
  • EF 600mm f / 4L USM  (all lens versions)  + EF 2x I and II
  • EF 800mm f / 5.6L IS USM + EF 1.4x I, II and III
  • EF 1200mm f / 5.6L USM + EF 1.4x I, II and III

Summary

Advanced autofocus capabilities with an effective f / 8 lens aperture are just one example of how the EOS-1D X Mark II can open new doors for professionals and serious SLR enthusiasts alike. Being able to use lighter, faster lenses with tele-extenders and still have powerful autofocus may mean an easier journey for some photographers.

Keep this feature in mind when exploring the EOS-1D X Mark II, and consider its potential usefulness when considering the many possibilities this camera offers to Canon's most demanding customers.

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