This is from the D800 Feature's page on Nikon's website:

"Nikon's revolutionary Advanced Scene Recognition System, introduced with the flagship D4 camera, is also employed in the D800/D800E. At its core is a 91K-pixel RGB sensor that meticulously analyzes each scene with the fine resolution. The RGB sensor can recognize your scene's colors and brightness with unprecedented precision, then use that information to implement various automatic controls and give you more natural-looking results. The real breakthrough, however, is that the sensor can detect human faces with startling accuracy when shooting through the optical viewfinder".

According to Page 94 in the D800 manual, Face Detection through the viewfinder is enabled by simply rotating the subcommand dial until it reads "Auto". If it's in AF-S, the focusing system will detect and give priority to faces. If it's in AF-C, it's supposed to track the face.

Face Detection is nearly flawless with Live View, but I have not been able to get it to work when using the viewfinder. Those with D800's, are you seeing similar results? Alternatively, if you've gotten it to work, what's the secret?

Good question.

Tried in Live View, worked great. The focus follow where you can lock on a subject and it follows it worked well with my test subject... my dog.

Tried viewfinder... AF-S Auto just works like normal auto... did not see any locks on faces. [tested using a picture of someone, ya it worked]

Set it to AF-C Auto and it locked on the face and if I moved the camera around the focus point followed the face as I would imagine should be expected.

i use Face detection in the view finder with AF-C and it does extremely well.

I think face detection only works when you have the camera set to 3d focus tracking on continuous....
You can focus on whatever you want then recompose and as long as your object stays within the focus grid you will achieve focus

hardlyboring wrote:
I think face detection only works when you have the camera set to 3d focus tracking on continuous....
You can focus on whatever you want then recompose and as long as your object stays within the focus grid you will achieve focus

3d tracking has been around for years, and it's notably different, at least in theory, than Face Detection. The primary difference, IMO, is how the initial focus point is selected. With 3d tracking, you get to choose the initial focus point. With face detection, you just press the shutter, and the camera should locate and lock on to a face. It appears that my D800 may very well detect a face, but it it ends up locking on to an ear, chin, hairline, some piece of clothing, a necklace, etc.. It behaves like a hybrid between face detection and 3d tracking, where it detects a face, but can't seem to lock onto the facial triangle made up of 2 eyes and a mouth. Maybe my expectations are just too high after seeing what it's capable of doing in Live View, .

I wish there would be a few more replies here. In live view, mine is great, but not through the viewfinder at all.

hardlyboring wrote:
I think face detection only works when you have the camera set to 3d focus tracking on continuous....
You can focus on whatever you want then recompose and as long as your object stays within the focus grid you will achieve focus

No, 3D and Face Tracking are two different things.

The OP is correct. Face tracking occurs in AF-C Auto and it's pretty darn accurate. I rented a D800 and an 85 1.4G and Face Tracking had no problem following moving subjects. However, I never tried it wide open and I never tried it in a crowd of people. I think in those situations you might be better off selecting the focus point yourself

I shoot AF-C Auto about ten minutes each event/wedding to test it, and it's probably the worst 10 minutes of images I get (don't worry, I choose dull moments where I'm shooting nobody special to the event/wedding).

I've tried all the settings with a D4 and a D800... Face detect in viewfinder isn't a thing. You might get "lucky" and it might lock onto a face just because, but it doesn't lock onto the face out of technological advancements in autofocus. And it sure as hell isn't as accurate and sharp as when I focus on the eye and recompose or when I set an single off center point and shoot.

I bought the D4/D800 specifically for this feature, and so far no dice.
Am I doing something wrong?

adamdewilde wrote:
I shoot AF-C Auto about ten minutes each event/wedding to test it, and it's probably the worst 10 minutes of images I get (don't worry, I choose dull moments where I'm shooting nobody special to the event/wedding).

I've tried all the settings with a D4 and a D800... Face detect in viewfinder isn't a thing. You might get "lucky" and it might lock onto a face just because, but it doesn't lock onto the face out of technological advancements in autofocus. And it sure as hell isn't as accurate and sharp as when I focus on the eye and recompose or when I set an single off center point and shoot.

I bought the D4/D800 specifically for this feature, and so far no dice.
Am I doing something wrong?

I have had decent results using face recog when shooting one person on a stage, sometimes there might be a non-moving body. Haven't tried it with a group of people. I'll give it a try next weekend. Using a D4.

Yeah I have two D4 bodies and a D800 and yes it detects a face (when you zoom in slightly it'll show white boxes around the faces) BUT it doesn't actually focus on the faces.. Took tons of shots over the course of a few months and it's as hit or miss as other 45+ point autofocus systems. It hits on something, but that may be an arm, or a shoulder, or hair etc.. Not always the face (if it does, it's coincidence or the type of shot).. This is confirmed over about 10k in people shots over 3 cameras.

Yes in liveview it works wonderfully.. Wish Nikon could fix this to work through the viewfinder.

I just say no to FD. My focus point selection in AF-C is more consistent than turnin' over the reins...
probably by a factor of 10