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WOOCS 1.2.4

Making full use of Autofocus with the Phase One XF

Making full use of Autofocus with the Phase One XF
9th May 2018 Al Simmons

 

 

In October last year Phase One introduced Feature Update 4 for the XF Camera System. This added various improvements to the focussing ability of the camera, and one which brought particular advancement was Autofocus-Recompose mode (AFr).

It hasn’t been widely publicised by Phase One themselves, but once you start using the feature, you realise what a significant step forward it is in making the XF a more flexible and effective system. For those who miss the moveable focus points that DSLR cameras have introduced, AFr offers a more accurate – and arguably quicker – way of achieving this in a medium format system.

When shooting on a medium format sensor, depth of field is much shallower at the same aperture to 35mm. With the XF having a centre focus point, recomposing after focussing is necessary (without manual focus), and this can more often than not lead to a focus drift after recomposition. This is not a fault of the camera, but simply a factor to be aware of when shooting medium format. What Phase One have done with AFr (along with all the tools added through Feature Updates) is work around an issue with a smart and swift tool that opens up the creative possibilities without slowing you down or restricting what you can achieve.

The obvious benefits are for portrait photographers, but the feature extends to any shooting situation where focusing and recomposing is necessary. From testing it ourselves – even with the 150mm f2.8 lens – a heavy lens, where depth of field is incredibly shallow, it leads to 100% success in keeping your focus where you want it to be.

How does it work?

AFr mode works by shifting the focus of the lens to a closer focal plane after the confirmation of focus and recomposition of the frame. The XF Camera evaluates the movement of the camera from the previous exposure to anticipate which direction the focus should be changed. The makes it an intelligent system, in that the camera learns your shooting behaviour and can adapt quickly to ensure optimal performance.

How do I know if it has successfully adjusted my focus?

AFr mode has three ways of confirming to the photographer whether it has done it’s job. An audible beep can be turned on to indicate the success or failure of the camera to anticipate your movement. The focus marks (in the Prism or on the XF top panel if with the Waist Level Finder) will also indicate success or failure by flashing following the capture. Within the IQ preview settings, you can also use the Zoom to Focus preview option, which will automatically zoom 100% to the original location that you confirmed your focus. This gives audible and visual communication to the photographer that it has worked. Depending on the extremity of your recomposition, it might take a shot or two for the system to compensate and get it right, but once it has learned how you’re working, shot after shot is spot on.

 

Sample shots – using 150mm at f2.8 with IQ3 100MP digital back and our beautiful model Michael!

Without AFr mode:

Recomposed shot

 

Crop

 

With AFr mode:

 

Recomposed shot

 

Crop

 

Though the shot captured using the Autofocus system without AFr is quite useable, you can see how much of a difference the shift in focus makes to achieving absolutely critical focus.

AFr mode is activated through the Capture Setup menu in the XF, and is currently supported with the following lenses:

  • 55mm LS f/2.8
  • 80mm LS f/2.8
  • 110mm LS f/2.8
  • 120mm LS f/4.0 Macro
  • 150mm LS f/2.8
  • 150mm LS f/3.5

Instead of compromising image quality, AFr mode introduces an intelligent and quick tool to work around the shallow depth of field factor of medium format photography.

Get in touch for more details or to see the XF camera in action for yourself. If you would like to have a look at the RAW files for yourself,  email al@teamworkphoto.com and we will be happy to send over.

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