Sony Eye AF
Sony Eye AF, or eye autofocus, is perhaps THE killer feature on modern Sony cameras, particularly for portrait photographers. The newest generation of Sony cameras (A7riii, A9, A7iii) have seen advancements in this feature. Unfortunately, I’ve seen some misunderstandings about this rather simple feature on the internet, so I hope this post is a good guide.
What is Sony Eye AF?
Lots of cameras have face detect features. Sony has taken this a step further, eye AF automatically seeks out and focuses on the subject’s eye. It is supposed to lock focus on the subject’s nearest eye. In earlier Sony cameras, this feature only worked with a still posed model while shooting in AF-S mode. Now, this feature works in AF-C mode as well, allowing the eye to be tracked while the subject is moving.
As of April 2019, a major firmware update changed how this feature works. Additionally, it works differently in Sony cameras.
How is this different than a dSLR?
Many modern dSLRs have pretty good tracking capabilities but none specifically seek out an eye. Nikon cameras have excellent 3D tracking. The 3D tracking can indeed be used to track a subject’s eye — If the eye is fairly large in the frame and if the photographer first initiates focus specifically on the eye. Then, as long as the eye stays pretty large in the frame and as long as the subject stays within the focus points, the camera can follow the eye.
In contrast, finding the eye with Sony eye AF is much faster and effective. The subject’s eye need not be especially large in the frame. You do not have to first move a focus point to the eye — the camera can automatically locate it. And since the newest Sony cameras have focus points covering most of the frame, the eye can be tracked to the edges of the frame.
How well does Sony Eye AF work?
For the most part, Sony eye AF works very well but it is not perfect. A little green box should light up around the focused eye. Unless the face is especially tiny in the frame, the camera does an excellent job of finding an eye. While Sony eye AF should lock on to the nearest eye, there are times you will see the green box jump between the eyes. If the head of the subject is tilted so there is a big relative difference in focus distance, then the camera reliably will pick the nearest eye. But if the focus distance of the two eyes is pretty close, there are times the eye AF will pick the further eye. More often than not, the camera picks the right eye, but you should be aware there are times the camera will pick the wrong eye.
One would think having multiple subjects would create confusion but the camera handles this well. Using flexible spot focus, just move a focus point closest to the face that is your main subject, and Sony eye AF will lock on to the eye of that individual.
The quality of the focus is the biggest issue. In most cases, especially if you have a bit of depth of field, it is very accurate but it is not always perfect. If you have especially narrow depth of field, there will be times when it may focus on the eye lashes instead of the iris of the eye. If you are pixel peeping a 42 megapixel sensor you may notice this millimeter difference in cases of extremely narrow depth of field, as in this example:
You can click for larger images. When viewed normal size, the focus looks perfect. When closely examined, where focus should be on the camera-right eye, you will see that the camera just very very slightly front focused. Thus, the technology is not quite perfect but it is certainly very good. The above example was in low light. Unsurprisingly, the focus may be less accurate in low light. Below, in better light, see an example where the eye-AF worked perfectly despite extremely narrow depth of field:
Are these results more consistent and more accurate than a traditional dSLR? Most of the time, I believe so. As discussed below, there are some ways to improve the reliability of eye AF. First…
How to set up Sony Eye AF:
There was a major change in eye-AF in April 2019. Previously, a custom button had to be assigned to eye-AF and it was only active when the button was pressed. It’s can now be set so that it is “always on.”
The set-up for the SonyA7riii and Sony A7iii…. You will find a selection to set up “Face/Eye AF.”
If you select “Face/Eye AF set,” it takes you into the set-up menu for eye-AF:
Simply turn on “Face/Eye Prty in AF,” and the camera will automatically prioritize faces and eyes. Previously, faces were prioritized but you had to take an extra step to get focus on the eyes. The extra step is now eliminated.
Animal eye-AF
Note in the menus listed above, you also can choose “human” for your subject. Clicking would allow you to choose “animal.” Sony is expanding eye-AF to work with animals. Currently, it works with dogs and cats, but you need to first tell the camera to look for animals, not humans. Unless you make this change in the menus, it will not work on animals.
Setting a Custom Key for Eye-AF
In older Sony cameras and prior to the firmware update, in order to use continuous tracking eye AF, it had to be assigned to a custom button. By default, it was assigned to the center of the control wheel which is not the best place for it. If supported by the lenses you are using, I loved assigning eye AF to the focus hold button. Other popular and easy places to assign it on the Sony A7riii and Sony A7iii include the AEL button and the AF-ON button.
Even with the new firmware, you can still choose to assign a button to eye-AF. Depending on the focus mode you are using, it can still be helpful to have a button assigned to the function.
To use Sony Eye AF, you hold down the assigned button, a green square will appear over the eye, and you keep the button held until you depress the shutter button. The Sony Eye AF will override any other focus area settings.
Sony A9 and Sony A6400 Eye-AF
The Sony A9 and Sony A6400 are the first Sony cameras to feature “real time tracking” which also changes eye-AF a bit. This post demonstrates real time tracking. Real time tracking prioritizes the face and eyes when tracking a human subject. It adds another element to eye-AF:
Since you are not going to universally shoot the left or the right eye, you can keep this in “auto” and it should select the nearest eye. You can then assign “right/left eye select” to a custom button, which will allow you to override the camera on an individual shot basis.
How NOT to set up Sony Eye AF
In setting up their Sony A7riii and A7iii cameras, many users are coming across this screen (Camera menu 1, page 7 of 14)
Ignore “Eye-Start AF.” It has nothing to do with Sony Eye AF. It is a feature that can only be used when adapting Sony A-mount lenses (Sony’s old pre-mirrorless system). I’ve seen many people bewildered as they try to turn on eye-AF with this menu item only to find it grayed out. Once again, this menu has nothing to do with Sony Eye AF and can be ignored by most users.
Using Sony Eye AF in AF-S and AF-C
There is a totally false myth I’ve seen repeated many times on the internet recently in regard to the Sony A7riii. Many people are claiming that Sony Eye AF only works in AF-C and not in AF-S. This is completely false. As I will explain, it can actually work better in AF-S than in AF-C.
It helps to first remember the difference between AF-S and AF-C. In AF-S mode, the camera locks focus when you half-press the shutter button (or AF-on button). The focus will not adjust if the photographer or the subject moves. In AF-C, the focus will constantly re-adjust as the photographer or subject moves. In AF-C mode, the Sony A7riii and A7iii primarily rely on the camera’s phase detection system: extremely fast and good for directional focus. In AF-S mode, the Sony A7riii and A7iii will use the phase detection system to initiate focus acquisition but will then use the camera’s contrast detect system to confirm precision of focus. (Contrast detection is slower and more prone to hunting but it is ultimately more precise and accurate).
In early Sony mirrorless cameras, eye-AF only worked in AF-S mode. You held down the eye-AF button and a green dot would freeze over the subject’s eye. Many reviewers commented as to why the camera couldn’t just find the eye by default, why the need to push an extra button.
What Sony hasn’t publicized is that they addressed this very issue. Now, when using face detect in AF-S mode, the camera seeks out the nearest eye by default. Instead of a green box freezing over the eye, the green box will only flash for a moment and then disappear. Many people have concluded that since they aren’t seeing the green box, they aren’t getting eye-AF. This simply isn’t true. As part of face detection, the camera has sought out the eye by default.
Recall that AF-S is still a locked focus. So while the camera has locked focus on the eye, focus will not change if the photographer or subject moves. So AF-S does not track the eye, but it does find the eye. As I mentioned above, the camera will do a contrast detection confirmation in AF-S mode. Therefore, this can lead to more accurate focus, as long as the photographer or subject is not moving.
In AF-C mode, Sony Eye AF does not come on by default. You hold down the custom button,the little green box will track the eye continuously. If the face is very small in the frame and the camera cannot find the eye, then the camera will still use face detection to find the face.
To use AF-C or AF-S with Sony Eye AF?
When I shot dSLRs, I always used AF-S for posed portraits. I did this because there were a limited number of focus points. Using AF-S, I could lock focus on the eye and then re-compose my shot. As long as my re-composition didn’t change angles too badly and as long as my subject didn’t move, I could get pretty good autofocus right on the eye ball. If my subject was moving, I had to use AF-C but I was limited to the more central part of the frame.
Because Sony Eye AF with AF-C allows tracking of the eye across almost the entire frame on the Sony A7riii and Sony A7iii, I find myself using AF-C almost all of the time. And I mostly get very accurate autofocus right on the eyes. Yet there are still times where it could be beneficial to use AF-S. Certainly, AF-C is extremely beneficial when shooting candids, children, street photography, etc. If you are shooting posed portraits, using AF-S still gives the benefit of the contrast detect confirmation which can make the focus just a bit more precise. As in these examples:
In the first image, eye-AF was used in conjunction with the AF-C. In the second photo, the eye-AF custom button was used but the camera was set to AF-S. In the last photograph, I just utilized face detection in AF-S. All 3 images are close crops at 50mm F1.4 with very narrow depth of field. In all three photos, focus was on the eye at camera right. You will notice that in the first photograph taken with AF-C, focus on the eye might be just very very slightly off while focus is absolutely perfect in both AF-S crops. As you will note in the last image, there was no need to even press the eye-AF button to get perfect autofocus when in AF-S mode.
Conclusion:
Sony Eye-AF is a bit of a game changing feature. No traditional dSLR makes it as easy to quickly and reliably grab autofocus of the eye anywhere in the frame. This is a feature that should be used by every Sony mirrorless camera owner. In the Sony A9, Sony A7riii and Sony A7iii, the eye-AF has become very advanced but it is still not perfect. It can be a bit more accurate if you use AF-S (if your subject isn’t moving) and if you have plenty of light.
I’m not afraid of “misses” with eye-AF because even where it does miss by a slight amount, it is never off by very much and I really would only notice when I’m pixel peeping.
Sony Eye-AF is a big reason why the Sony A7riii and Sony A7iii should be at the top of the list for any portrait or event photographer.
If you’re considering purchasing these cameras from Amazon, I would request that you consider supporting this site by using these links to get to Amazon for your purchase. (You won’t pay any extra):
The best portrait lenses for the Sony A7riii and Sony A7iii are:
- Sony Zeiss FE 55mm F/1.8 (my review here)
- Sony Zeiss 50mm F/1.4 (My review here)
- Sony FE 85mm F/1.8 (best value in the entire Sony lineup) (review here)
- Sony FE 85mm F/1.4 GM (review here)
- Sony FE 100mm F/2.8 GM STF (review here)
- Sony 135mm F/1.8 GM
- Samyang / Rokinon 85mm F/1.4 (review coming soon)
Thank you for reading.
