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02-06-2012, 03:38 PM   #1
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Face Recognition

Hi Everyone,

Just wondering how you have found the Face Recognition on the K5 (live view).

I find it rather terrible.

My main gripe is that the camera might pick up a face when i first turn LV on, and it will focus on that. But then, when i recompose the camera for my next shot, the focus point stays in the same place, and the camera doesn't seem to do any more face detecting.

Is this normal? Or is my camera acting strangely? I ask because i'm sending my camera off for some other warranty repairs, and would like this seen to at the same time if it is abnormal.

Camera settings: Av, auto ISO, RAW. Doesn't matter if single- or multi-point focus is selected.

Any comments or help is welcome!

-Benj

02-06-2012, 05:01 PM   #2
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The LV CDAF is quite bad- but honestly, how often would you even need face detection? What I do is set it up spot focus and use the VF, because it's guaranteed to work

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02-07-2012, 03:05 PM   #3
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QuoteOriginally posted by Adam Quote
What I do is set it up spot focus and use the VF, because it's guaranteed to work
Yeah, that's what I do too. But i just wanted to make sure the Face Detection was working as it is supposed to, as this is my last opportunity to get it fixed under warranty if it isn't.

So are you saying that it is working "normally" then? Do all K5's act like this?

The thing that annoys me most is that it keeps the point where the face was as the focus point for subsequent photos - even if there is no face there in subsequent photos but there are faces in other parts of the frame! Shouldn't it either 1) recognise there are new faces and re-adjust the focus point onto one of the current faces or 2) re-center the focus point if no faces are found?

If there is "nothing wrong" with my camera, then oh well i guess.
02-08-2012, 12:26 AM   #4
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I've really only used the feature once, but I believe that's how it works. I hope someone else can confirm this for you! I doubt there's anything wrong with the camera, though- but just in case, are you running the latest firmware?


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02-08-2012, 12:59 AM   #5
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Face regcogniition is software so if anything is wrong with it, reinstalling the firmware would solve it.
02-08-2012, 02:20 AM   #6
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I don't have the camera with me so I cant test it right now, but I would expect the face recognition function to search up faces in new positions every time I ask for AF. Doesn't that work?
02-08-2012, 05:17 AM   #7
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Yes, i have the latest firmware.

QuoteOriginally posted by Gimbal Quote
I would expect the face recognition function to search up faces in new positions every time I ask for AF. Doesn't that work?
Not on my camera! Hence the question. It would make sense to me for the face detection to become active each time i ask for AF. But it only really works the first time I turn on Live View.
02-08-2012, 11:38 AM   #8
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I tried it now, first I have to wait for it to find a face which is then marked with a yellow rectangle. I press AF and it focuses on the face, I then let go of AF and the rectangle turns white for a moment and then yellow again as it finds the face again. The yellow rectangle stays on the face even if I recompose (it continuously tracks the face with the yellow rectangle).

Sometimes however it doesn't find the face and the rectangle turns white and stays in the same position as it where.

Thus I think your camera is ok, sometimes it just might have a problem with some faces/light/shadow/moon-phase being wrong.

02-11-2012, 11:43 PM   #9
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I tried it again, and it seems to work as Gimbal says. However, it's just not as good as tracking faces as i thought it should be

So i just had to make sure the face(s) fill a majority of the frame.

The camera is off getting the rest of the stuff fixed under warranty now. Nice to get it fixed for free, not nice not having a camera for a month!
02-15-2012, 08:14 AM   #10
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Ok, I THINK I might have an answer to this "problem".. Not 100% sure, you need to test it out.
How face detection(FD) technology works is by detecting a set value, to detect faces, that has been programmed in the software. What exactly the software calculate differs from model to model. But my understanding is that, these faces that are detected MUST be very spot on focus. So what does this mean? Aperture and DoF.... The technology in PnS cameras will set the aperture accordingly depending on the DoF needed to obtain a correct focus. When you set your camera on AV mode, the camera/software will be limited to whichever faces that are WITHIN the resulting DoF, from your desired/selected aperture. Thus, when you recompose, some faces might be out of the DoF ever so slightly.

Do a comparison, put everything into auto and get as many faces constantly detected and see the selected aperture by the camera. And then, try set to AV mode, choose YOUR own aperture, and frame the same exact faces (don't ask them to move... LoL!)... Notice and remember the number of faces detected. Then, SET the aperture to the value that the camera had set when it was in full auto mode. Compare the results amongst the 3, and you will see what i mean.. If you are going to do it, use a tripod and also same subjects at same location. From what I did the last time, my suspicion was correct.. Face detection technology is actually more like a gimmick. Only thing that it does is helping to set, in relation to the aperture value, a more accurate DoF for all the faces in the frame.. Haha! Technology and it's "gimmicks".. :P
02-15-2012, 02:59 PM   #11
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I do think the face detection is a little bit of a gimmick, but Olympus's new E-M5 has face detection that is pretty cool. You can program it to recognize the face, and focus on the eye closest to the camera. It actually recognizes the eyes and selects focus for the closest eye automatically. Not sure how well this works, but the technology is pretty cool. With Pentax PDAF the center AF point is the size of a golf ball and grabs anything of contrast close to the face. Working with singers at wide apertures it often grabs the microphone in front of the face. Can't tell you how many pictures of really sharp microphones I took before realizing just how large the center AF point is (4x larger than the red square).
02-15-2012, 03:07 PM   #12
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I don't have the K-5 but the face detection of my Fujifilm F200EXR and my sister's 4 years old Canon P&S work great, truly P&S. There is no reason the K-5 can't do the same other than poor algorithm.
02-15-2012, 03:18 PM   #13
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CDAF uses the image processor for AF control. I'm not sure how much work Pentax put into it for the K-5. PDAF has its own sensor/processor which frees up the image processor. By moving to CDAF you are taking up more processing power which might not be a good thing as it takes away from actual image processing.

I think the Prime M is optimized for CDAF and HD Video. The K-01 has a lower ISO range and is only 12-bit, so Pentax has scaled it back. Pentax is probably trading the IQ and DR of the K-5 (PRIME II) for faster CDAF and better HD video support (PRIME M).
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