Eye AF is Sony’s DSLR killing technology. Watching Sony a9 photographers use it stirred incredible envy and not before long, I had pre-ordered two Sony a7iii camera bodies.

If you are new to Sony, like I was, eye AF is a game changer. To turn it on and enable it in your photography is however, a bit of a hidden process. In this blog post, I am going to show to do it with ease.

By default, the center button on your Sony a7iii will activate eye AF. However, I find this button assignment to be hard to reach with my thumb whilst shooting. I will be showing you how you can assign the “AF-ON” button to trigger eye AF on your Sony a7iii.

Here is how you enable eye AF on your Sony a7 iii camera:

  1. Make sure you top dial is not set on a movie recording mode (M, A, S, P are fine).
  2. On menu tab 1, page 5/14, make sure Focus Mode is set to “Continuous AF”.
  3. On menu tab 2, page 8/9, select photo mode “Custom Key”.
  4. To assign a button to trigger eye AF, scroll across to page 2 of the Custom Key settings menu. By default, eye AF is triggered by the Center Button. I suggest leaving this as is.
  5. Go to page 3 of the Custom Key settings menu.
  6. Select “AEL Button”.
  7. To assign eye AF to the AEL button, scroll to page 4/22 and select “Eye AF” on the bottom of the page.
  8. When photographing your subject, use your thumb to hold down the AEL button to trigger eye AF. A small green box will appear once your a7 III has detected an eye. If the camera cannot detect an eye, it will default to face detection (seen as a white box around your subject’s face).

Things to change while you are inside the photo mode Custom Key menu

Since you are already here, you might as well make some changes to make your life easier when out photographing. I suggest assigning the following functions to these buttons:

  • Custom Button 1 (C1): ASP-C S35 / Full Frm Sel.
  • Custom Button 2 (C2): Focus Area
  • Custom Button 3 (C3): Focus Mode
  • Custom Button 4 (C4): Silent Shooting
  • Left Button: Drive Mode (default)
  • Right Button: ISO (default)
  • AF-ON Button: AF On
  • Focus Hold Button: Eye AF

How to set up back button focusing on the Sony a7iii

To enable back button focusing (BBF) on on your Sony a7 III, we need to assign the AF-ON button to trigger autofocus. But in order to do so, you first need to follow these steps:

  1. On menu tab 1, page 6/14, go to the last item “AF w/ shutter”.
  2. By default, “AF w/ shutter” will be on. In order to enable back button focusing, turn this off.
  3. Go to menu tab 1, page 7/14, and turn “Pre-AF” to “Off”.
  4. Go to menu tab 2, page 8/9, select photo mode “Custom Key”.
  5. Scroll across to page 3 of the photo mode Custom Key menu, select AF-ON Button and select “AF On”.

And you’re ready to use back button focusing!

To focus, press and hold AF-ON and when you are happy with the timing and/or composition of the frame, press the shutter button to capture the image.

What is back button focusing and why should you use BFF?

I’ll let Tony Northrup explain. I’ll just make a mess of it.

 

What lenses work with eye AF?

All native Sony FE lenses will work with eye AF on the a7iii. These include:

  • Sony FE 24-105mm f/4 G OSS
  • Sony FE 24-70mm f/2.8 GM
  • Sony FE 24-240mm f/3.5-6.3 OSS
  • Sony FE 28-70mm f/3.5-5.6 OSS
  • Sony FE 28mm f/2
  • Sony FE 35mm f/2.8 ZA
  • Sony FE 35mm f/1.4 ZA
  • Sony FE 12-24mm f/4 G
  • Sony FE 16-35mm f/2.8 GM
  • Sony FE 16-35mm f/4 ZA OSS
  • Sony FE 50mm f/1.8
  • Sony Planar %* FE 50mm f/1.4 ZA
  • Sony Sonnar T* FE 55mm f/1.8ZA
  • Sony FE 85mm f/1.8
  • Sony FE 85mm f/1.4 GM
  • Sony FE 100mm f/2.8 STF GM OSS
  • Sony FE 50mm f/2.8 Macro
  • Sony FE 90mm f/2.8 Macro G OSS
  • Sony FE 70-200mm f/2.8 GM OSS
  • Sony FE 70-200mm f/4G OSS
  • Sony FE 70-300mm f/4.5-5.6 G OSS
  • Sony FE 100-400mm f/4.5-5.6 G OSS
  • Sony FE 500mm f/2.8 GM OSS
  • ZEISS Batis 18mm f/2.8
  • ZEISS Batis 25mm f.2
  • ZEISS Batis 85mm f/1.8
  • ZEISS Batis 135mm f/2.8 OSS
  • Tamron 28-75mm f/2.8 Di III RXD
  • Sigma 14mm f/1.8 DG HSM Art
  • Sigma 20mm f/1.4 DG HSM Art
  • Sigma 24mm f/1.4 DG HSM Art
  • Sigma 35mm f.1,4 DG HSM Art
  • Sigma 50mm f/14 DG HSM Art
  • Sigma 60mm f/2.8 DG MACRO Art
  • Sigma 85mm f/1.4 DG HSM Art
  • Sigma 105mm f/1.4 DG HSM Art
  • Sigma 135mm f/1.8 DG HSM Art
  • Rokinon AF 14mm f/2.8 FE
  • Rokinon AF 24mm f/2.8 FE
  • Rokinon AF 35mm f/1.4 FE
  • Rokinon AF 35mm f/2.8 FE
  • Rokinon AF 50mm f/1.4 FE

But what about non-native Sony FE lenses? How about Canon EF lenses using a Metabones IV adapter?

I spent some time digging around and these were my findings.

Does Canon EF 85mm f/1.2L II work with Sony a7iii eye AF?

Yes, eye AF does work with the Canon EF 85mm f/1.2L II on the a7iii using a Metabones IV adapter. It will track a subject with eye AF. It will work even when the 85L is shot wide open at f/1.2.

Does Canon FE 35mm f/1.4L II work with Sony a7iii eye AF?

Yes, eye AF does work with the Canon EF 35mm f/1.4L II on the a7iii using a Metabones IV adapter. It will track a subject with eye AF. It will work even when the 35L is shot wide open at f/1.4.

Does Canon EF 70-200mm f/2.8L II USM work with Sony a7iiieye AF?

Towards the 200mm mark, the a7 III had some difficulty with achieving eye AF using a Metabones IV adapter. Sometimes the camera would take a prolonged time to find eye AF. In these instances, the a7 III was always able to achieve face detection. Once face detection was achieved, eye AF became easy.