Issues with face and eye detect.

[Martin Kristiansen]

I have picked up a issue with face and eye detect on both the Sony A9 and the A7riii.

I resisted auto focus for years. Most of my photography the last while has been tripod bound studio, landscape and architectural work. Much more recently I began doing more sport, street, documentary, fashion and so on. I am even doing a few weddings and some events again, something I haven’t done for years. Obviously AF is a real advantage and so I ended up with the gear I now have. AF is not as simple as I hoped and getting the right camera with the right lens and the correct settings is crucial to its success.

But I have found an odd problem.

In South Africa we have a big variety of skin colours. From west African populations that are extremely dark to blond blue eyed whites of Dutch decent. In commercial photography advertisers try to be as representative as possible and rather than going for mixed race people, we call coloureds over here, I  frequently have to contend with a shot that has a white man in a navy shirt next to a black west African woman in a white shirt. Thank goodness for modern high dynamic range sensors. Challenging but so it goes. We have techniques.

The problem is focusing. The cameras will almost always focus on the white face. If there are 5 people in frame and one is white the white person will be critically focused if I shoot an event I end up with all the white people in focus even though we are a minority. In my own family the one black woman is frequently the person that turns up with far fewer images where she is sharply focused.

There are ways around it but it takes work and concentration and an awareness of the problem. I am not for a moment saying it’s a racist thing on the part of camera manufacturers. I think it’s the same issue that causes backlit faces to be harder for the AF to deal with. White faces have more contrast and simply reflect more light so the AF detects them faster and locks on. Black faces being darker are not selected by the AF system if you are using wide or zone focusing. If you allow the camera to choose the face with face detect is consistently chooses the lighter face.

I find I cannot trust zone focus area with face detect or wide with face detect. The AF will always pick the white faces in this mode. It’s better to select a large spot and move it over the face you want sharp and force the AF to select that face. You need to be aware that the AF is likely to quickly abandoned that dark face and hop to a white face if one should move close the the auto focus zone you have selected. It makes it harder in situations where as long as one face is sharp you are good to go, now you need to deliberately decide on every shot which face that should be. When shooting an event for example I need a balance of white and black faces that are sharp. Not just the white faces.

Perhaps no issue in places where most people are white but for those of us in countries where that is not the reality it might be worth taking note of this characteristic of face and eye detect AF systems.

Likely not of much interest to most.

[petermfiore]

Like everything in photography, it's a matter of understanding one's equipment and getting on with it.

Peter

[Martin Kristiansen]

Like everything in photography, it's a matter of understanding one's equipment and getting on with it.

Peter

Quite right. And sometimes it throws up an issue you may not have considered.

[KLaban]

Martin, I can't say I'm surprised about this issue and will be looking out for it when using my Z7 in similar circumstances.

That said I rarely shoot white faces.

[elliot_n]

The cameras will almost always focus on the white face ... I am not for a moment saying it’s a racist thing on the part of camera manufacturers.

Well, as you describe it, the behaviour of the camera is racist.

Is this because the camera manufacturer is racist? I suspect it is.

[Martin Kristiansen]

Well, as you describe it, the behaviour of the camera is racist.

Is this because the camera manufacturer is racist? I suspect it is.

As I described it and I thought made quite clear the camera finds it easier to focus on something brighter and with more contrast. This behavior is easily seen without face and eye detect. We all know that as light levels fall off the AF performance also falls off. A west African has less light coming off his face than a white person under the same lighting conditions, that is a fact not a racist statement. It makes sense for the AF system to work with the brighter more contrasty parts of a scene because that will boost performance. I believe the unintended consequence of this is darker skinned people are less likely to be selected as the target for AF systems featuring face and eye detect.

I don’t believe this issue has a racial bias at its foundation. That could be debated in the Coffee Corner but I am not going to get involved. I am bringing up these AF issues in case it will help someone working under similar circumstances to my own. I make adjustments for black skin when setting up studio lights. I see this  as a similar practical issue that might need to be addressed.

[Rob C]

As I described it and I thought made quite clear the camera finds it easier to focus on something brighter and with more contrast. This behavior is easily seen without face and eye detect. We all know that as light levels fall off the AF performance also falls off. A west African has less light coming off his face than a white person under the same lighting conditions, that is a fact not a racist statement. It makes sense for the AF system to work with the brighter more contrasty parts of a scene because that will boost performance. I believe the unintended consequence of this is darker skinned people are less likely to be selected as the target for AF systems featuring face and eye detect.

I don’t believe this issue has a racial bias at its foundation. That could be debated in the Coffee Corner but I am not going to get involved. I am bringing up these AF issues in case it will help someone working under similar circumstances to my own. I make adjustments for black skin when setting up studio lights. I see this  as a similar practical issue that might need to be addressed.

As you say, it's probably an illumination problem. Weddings push that problem for those who shoot them too, at least in traditional white dress/dark suit situations.

It's enough to drive people crazy. That said, I guess there will always be the situation where going back to manual makes more sense! Or perhaps using only central focussing point. I've never tried anything else... I still think life is governed by split-image central areas.

:-)

[Martin Kristiansen]

Absolutely Rob. Always a way around the problem. As long as you recognize that there is in fact a problem. I suppose that my point in a way.

[Jeremy Roussak]

Well, as you describe it, the behaviour of the camera is racist.

Is this because the camera manufacturer is racist? I suspect it is.

This post has been reported to me as being "entirely inappropriate". I don't agree. I think it is too fatuously silly to be elevated to the level of inappropriate. It contributes nothing to the discussion save for importing the buzzword "racist", which of course places the user on an unassailable pedestal and the accused irredeemably and unarguably in the wrong. Rod Liddle, a political commentator in the UK, generally spells with word with multiple "a"s, aptly mimicking the usual pronunciation of those who resort to it.

The post does merit a warning, though. Elliot, if you can contribute nothing but abuse, you will be silenced.

Jeremy

[scooby70]

I only have a first generation A7. My wife, her family and many of her friends are Asian.

I deliberately avoid using face detect (the A7 doesn't have eye detect) when I think this is going to be an issue for exactly this reason but even when placing the focus point on the face I want to focus on I've had a number of slightly out of focus shots especially when the subject is relatively small in the frame. Shots with the subjects face bigger in the frame are usually much less of an issue in my experience.

I suppose in time focus systems and algorithms will improve and the problem will lessen or even hopefully go away altogether.

To be honest I'd long since twigged what the issue was but hadn't mentioned it to anyone and didn't know that it could still be an issue with the newer cameras. I hope it gets sorted soon and in the meantime in situations when the focus can't be relied upon to lock onto the desired face I'll target the clothing and let dof do the rest or if time allows use manual focus.

[Slobodan Blagojevic]

Well, as you describe it, the behaviour of the camera is racist.

Is this because the camera manufacturer is racist? I suspect it is.

[John Camp]

There is a kind of corollary to this problem involving paper-media use of photographs with a mix of races, especially with newsprint. Black faces require a heavier application of ink than white faces. Newsprint is absorbent, and black and even brown faces often were reproduced as featureless blobs, even when the original photograph distinctly showed the features. This was a particularly terrible problem in high school basketball, often played in somewhat dimly lit gymnasiums (dimly lit by photography standards, but perfectly okay for the game and spectators.) The solution most papers went for was to deliberately over-expose; you might then be able to pull up black features, at the cost of white faces going excessively contrasty, to the point where the nose usually disappeared and you were left with hair, eyebrows and lips, which was better than losing the black faces altogether.

[Martin Kristiansen]

There is a kind of corollary to this problem involving paper-media use of photographs with a mix of races, especially with newsprint. Black faces require a heavier application of ink than white faces. Newsprint is absorbent, and black and even brown faces often were reproduced as featureless blobs, even when the original photograph distinctly showed the features. This was a particularly terrible problem in high school basketball, often played in somewhat dimly lit gymnasiums (dimly lit by photography standards, but perfectly okay for the game and spectators.) The solution most papers went for was to deliberately over-expose; you might then be able to pull up black features, at the cost of white faces going excessively contrasty, to the point where the nose usually disappeared and you were left with hair, eyebrows and lips, which was better than losing the black faces altogether.

In the old days as it were I actually wrote a custom dot gain curve for newsprint to help with this issue.

I wasn’t aware this issue would arise with Asian faces actually. I don’t think the issue is with facial features and the differences between races. I believe it to be a simple issue of contrast and light levels. The Sony system seems to err on the side of finding faces that don’t exist and on occasion will think some other pattern is a face when it is not. Also the system shows the same tendencies to ignore with  skinned Indians and they have very similar features to Caucasians. I did a shoot two weeks ago with a Chinese woman and a Japanese woman but both very light skinned and the camera handled it well. The black man who was backlit the camera didn’t pick up at all even when he was the only person in frame.

[Rob C]

I only have a first generation A7. My wife, her family and many of her friends are Asian.

I deliberately avoid using face detect (the A7 doesn't have eye detect) when I think this is going to be an issue for exactly this reason but even when placing the focus point on the face I want to focus on I've had a number of slightly out of focus shots especially when the subject is relatively small in the frame. Shots with the subjects face bigger in the frame are usually much less of an issue in my experience.

I suppose in time focus systems and algorithms will improve and the problem will lessen or even hopefully go away altogether.

To be honest I'd long since twigged what the issue was but hadn't mentioned it to anyone and didn't know that it could still be an issue with the newer cameras. I hope it gets sorted soon and in the meantime in situations when the focus can't be relied upon to lock onto the desired face I'll target the clothing and let dof do the rest or if time allows use manual focus.

The problem with focus existed, differently, with my 500 Series cameras using studio flash modelling lights that were too low to let me see well enough on faces (in full-length shots) and the answer was to have the girl place her hand flat against her stomach so the highlight on the rings could be used as the focussing area. Fortunately, large junk jewellery was often used! Shooting at around f6.3 or f8 was perfectly good enough to render the face sharp. The camera was tripod mounted, of course.

[KLaban]

I'll be interested to see how I fare with the Z7 face/eye detect when I next go to India where skin tones have a wide range.

[Alan Goldhammer]

I'll be interested to see how I fare with the Z7 face/eye detect when I next go to India where skin tones have a wide range.

It should be easy to do the control test by toggling off the eye detect feature and comparing similar shots to see what the difference, if any, is.  I did the firmware update on my Z 6 before we headed off on vacation to Canada last month.  90% of my images were landscapes so I didn't have this issue.  I had some shots of street musicians and even one of Leonard Cohen in Montreal (the face/eye detect worked perfectly on that one!!! )

[Manoli]

I'll be interested to see how I fare with the Z7 ...

/* slightly off-topic /*

Keith,
have you tried using any Leica M-series lenses on the Z series, and if you have was there an improvement in the smearing issue that affects the thicker cover glass Sony's ?

M

[KLaban]

/* slightly off-topic /*

Keith,
have you tried using any Leica M-series lenses on the Z series, and if you have was there an improvement in the smearing issue that affects the thicker cover glass Sony's ?

M

M, not yet.

I don't think there's much point in trying with anything wider than 50mm although I do have plans to test my 50 Zeiss C Sonnar on the Z. I wouldn't expect any M fit lens to perform as well on the Z but in any case that's not what I'm looking for. It might also be fun to try the 7 Artisans 50 f/1.1 but it's not a lens I own.

Best.

[Manoli]

I don't think there's much point in trying with anything wider than 50mm although I do have plans to test my 50 Zeiss C Sonnar on the Z. I wouldn't expect any M fit lens to perform as well on the Z ....

It's the 50 (and the75's) I'm curious about! It could be a motive for switching bodies, but for the time being it looks as though the only option is still a Kolarvision modified Sony.

Thanks for the feedback.
All best,
M

[Rob C]

It should be easy to do the control test by toggling off the eye detect feature and comparing similar shots to see what the difference, if any, is.  I did the firmware update on my Z 6 before we headed off on vacation to Canada last month.  90% of my images were landscapes so I didn't have this issue.  I had some shots of street musicians and even one of Leonard Cohen in Montreal (the face/eye detect worked perfectly on that one!!! )

Cohen might as well have been another test wall. Everything looks in focus on my little iPad, from here to eternity - hardly much of a test for af.