Face detection on D800 help please

henrik1963

I think I am a victim of face detection on my D800 - but may be I am doing something wrong?

I took a few pictures with my D800 + Sigma 35 1.4 Art wide open. The pictures had two faces in them but in a different focus plane. It seems like the camera was trying to get both faces in focus - impossible in this situation.

My settings for AF: AF-ON only - AF-C - Single AF point.

What am I or the camera doing wrong? Is face detect always on? Or can it be turned off?

Ironheart

I think face detect only works in live view. Didn't the sigma need a firmware update to work on a D800?

henrik1963

@Ironheart: The Sigma has been working fine when used for one face pictures - The DOF is very thin and I have been able to hit an eye with no problem before.

When reviewing the image I could see the two faces marked - that is why I suspect that it is Face detection at work.

Ironheart

The faces are detected after the fact in review mode. If you pull it into NX2 you can see the actual focus point selected.

Bokeh_Hunter

There is no way for the camera to know which face YOU want in focus. If there are more than one, it will do it's best to split the difference. Good with large groups but bad if you don't want that to happen or you are using a shallow f-stop. Personally I never use it and just use single point AF 90% of the time.

henrik1963

That is the point. I dont want this feature turned on. How do I turn it off? Is it supposed to be on when you use AF-C, single point and AF-On only?

Msmoto

Read Pages 93, 94 of the manual.
• Auto-area AF: The camera automatically
detects the subject and selects the focus
point; if a face is detected, the camera will
give priority to the portrait subject. The
active focus points are highlighted briefly
after the camera focuses; in AF-C mode, the
main focus point remains highlighted after
the other focus points have turned off.
AF-area mode can be
selected by pressing the
AF-mode button and
rotating the subcommand
dial until the
desired setting is
displayed in the
viewfinder and control
panel.
Face detect occurs in Auto AF Focus mode, but not in the other AF modes… Using the Single-point AF should correct the issue or use
Dynamic-area AF: Select the focus point as described on page 96. In
AF-C focus mode, the camera will focus based on information
from surrounding focus points if the subject briefly leaves the
selected point. The number of focus points varies with the mode
selected:
- 9-point dynamic-area AF: Choose when there is time to compose
the photograph or when photographing subjects that are
moving predictably (e.g., runners or race cars on a track).
- 21-point dynamic-area AF: Choose when photographing subjects
that are moving unpredictably (e.g., players at a football game).
- 51-point dynamic-area AF: Choose when photographing subjects
that are moving quickly and can not be easily framed in the
viewfinder (e.g., birds).
• 3D-tracking: The camera will track subjects.

In short, using the most manual mode you are comfortable with assures more control over what goes on.

henrik1963

@Msmoto: Thank you for taking the time to help :-) I have Thom Hogans book on the D800 and I come to the same conclusion as you have - that shooting in AF-C, single point should not activate face detect. If that is your conclusion :-)

It is hard to figure out when the camera uses face detect and when it is not.

I will take some more test shots to see if I have my settings the way I want them.

Thanks again

Ironheart

@henrick1963, if you are seeing white rectangles outlining faces during image review, that is merely the camera "recognizing" faces for you after the fact. It has nothing to do with which focus point is/was selected. That is displayed on a different screen as you rotate through the playback display options on the multi selector.

henrik1963

Thank you Ironheart, Bokeh_Hunter and Msmoto: I changed a3 - focus tracking - to off. Wether it was that or something else I don't know - everything seems to work now :-)

jj168

@henrik1963,
Msmoto is right. The face detection AF only work in auto area. Please note, obviously it will focus faces that are inside the AF coverage. It usially will focus on faces that clksest i believe. If you are in matrix metering, it will also use the rgb sensor to meter the face. Please keep in mind the camera is easy to be fooled, i.e it may failed to recognice faces when part or all of the face is blocked say by hand or wearing hat etc. You can easily try this by photographing someone in back lighting position.

henrik1963

@jj168: The D800 is a complex machine - lots of combinations to work out. Face detect in relation to AF and Face detect in relation to metering. Thanks for taking the time to answer. I think I have to study the manual when I get back home.

I would like to be able to turn things like Face detect off. I don't like the camera taking over without me knowing.