E-M5: Focusing explained

Started Jul 29, 2012 | Discussions
Timur Born
Timur Born Veteran Member • Posts: 4,778
E-M5: Focusing explained
24

I decided to collect all my current results that were spread and buried in several threads into one. If no more errors are found I will combine this and the "Rattlesnaking" thread into a user article for those people who don't read the forums.

Focus performance - speed and reliability

It should depend on the light of the scene and on your exposure settings. Changing exposure compensation and the accompanying exposure changes of Live View has an impact on auto-focus reliability/performance. When Live View has to push exposure of shadows for on-screen view both Live View and auto-focusing lags (Live View frame-rate drops).

  • Normal AF-S (and the initial AF of AF-C before hunting starts) changes contrast and gradations considerably before focusing and then turn it back to your own settings once focus is acquired. "Zoom AF" (and the later hunting part of AF-C) normally uses the current user settings and a slower focusing motor . Some shadow areas may lead "Zoom AF" to change contrast/gradations, too, though.

  • "Zoom AF" could repeatedly acquire focus on test objects in the shadows where both "Zoom Frame AF" and normal AF-S failed. The hunting part of AF-C also could acquire focus, but only when you let it settle down for a few seconds to stop the hunting. However I found a weaved basket in shadows where "Zoom AF" repeatedly did not acquire focus, while "Zoom Frame AF" and normal focus had no problem focusing.

  • Using negative exposure compensation with accompanying Live View exposure decrease can remove the lag. Of course this will have an impact on the image itself and thus is no solution.

  • Using Frame Rate "High" setting will never lag, but also never increase view of shadows to more than +1 EC (and turn off "Full Time AF"). The increased frame-rate itself may or may not have an impact, too, but it doesn't seem like it does. This will speed up auto-focus in shadows, but may leads to auto-focus failing completely in the very darkest shadows compared to "Normal" Frame Rate.

  • Using Gradations "Low" help to eliminate the lag, but of course has an impact on JPG shooting. Not so much on RAW shooting other than the Live View will be rather dark.

  • On the light side fortunately the E-M5 can still focus even when Live View has long clipped out to pure white (orange if you use highlight blinkies), so there still is something else than just 1:1 Live View = AF going on under the hood. Since blinkies are only a rough indication and often don't show real highlight clipping (even less for RAW) this may be one reason.

  • Using "Liew View Boost" effectively fixes Live View's exposure preview to some auto-settings that are not affected by your chosen Exposure Compensation. This may help against some lag in contrasty situations and where you want to apply positive exposure compensation.

As a major drawback this seriously affects Highlights & Shadow blinkies! And it does not solve lag completely, only "High" Frame Rate really does (and combining both doesn't make much sense then).

  • Release Priority is just a "priority" option, especially in AF-C it still allows to release the shutter even when the image is not in focus (during AF-C hunting that only settles after a few seconds). Sometimes the camera signals false "in focus" even in AF-S and thus lets you take out of focus shots.

  • Using more than a single focus area can cause the camera to hunt the focus forth and back before finally acquiring focus. On some targets it can happen with both 35 and 9 focus areas where 1 focus area focuses instantly (even when 35 and 9 decide to use the central area themselves), and it can happen with 9 focus areas where both 35 and 1 focus instantly. I didn't see the case where it just happens with 35, but wouldn't wonder if that can happen, too.

  • AF-C uses a combination of AF-S focus method and magnified focus method, first it tries AF-S and then it switches to hunting (using the same method as full-screen magnified) while the shutter is held half-pressed.

Even when the green dot is lit constantly you need to wait until the hunting settles/stops and then watch out not to shake the camera too much or getting other motion in frame. The green dot indicates by blinking that the camera detected motion (either camera shake or subjects inside the frame).

  • The green dot and green frame have quite some lag. They signal "in focus" (solid color) some time after focus has already been acquired (I guess something like a quarter or half a second). The audio beep signals "in focus" earlier and correctly.

(end of part 1, part 2 as reply)

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Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: E-M5: Focusing explained
3

(part 2)

The white box is independent of the green box!

Green box

In AF-S and the initial phase of AF-C the camera decides what to focus when you first half-press the shutter button.

The green box will show the focus area that was decided on at exactly that time (may be an eye or may be a whole face). Anything that happens afterwards, like subject/camera movement will not change the position of the green box/focus area. You can even turn the camera around while it is still busy focusing and the green box will still stay where it initially detected the face while the face may be somewhere else.

This includes spot metering on the green box area when a face is detected and Evaluative metering is active! When a face is detected on and off you have to watch out for vastly changing metering, especially because the E-M5 tends to detect face where there a none.

White Box

The white box on the other hand always shows the currently detected position of a face. This includes any camera or subject movement after first half-pressing the shutter button.

In AF-S this has no relevance whatsoever, focus will stay on the initial green box position! Even worse, if the camera initially did not detect a face due to shallow depth of field and then detects a face while focusing towards is you will only get a white box, but focus will remain on the normal (non FD) focus area. In this case you need to release and half-press the shutter again to get the "newly" detected face in focus.

In AF-C the white box will continuously be focused on while you keep the shutter half-pressed (initial focus is on the green box, but the white box supersedes it)! This even works if a face is detected afterwards initially half-pressing the shutter.

Again this also includes spot metering on the white box area when Evaluative metering is active and when a face is detected on and off you have to watch out for vastly changing metering.

Face Detection

  • Face Detection with AF-C will always auto-focus on a detected face while you keep the shutter half-press (which keeps AF-C running/hunting). Main drawback of AF-C is that it keeps hunting for several seconds after a frame got free of motion (camera shake or subject motion) and it will start hunting again once it detects any change. So you may get out-of-focus shots when you are using a too narrow DOF.

  • FD with AF-S will only auto-focus on the detected face when it was detected before you (half)press the shutter button. If a face is detected after you (half)press the shutter then you will see the white box around the face, but the E-M5 will not focus on it (but use the standard AF point). You have to release and press the shutter again to get focus on the then detected face.

The latter happens mostly with lenses that have a shallow DOF wide open, as the E-M5 usually keeps aperture wide open before taking the shot. You can get around that by using the "DOF Preview" button in combination with slower aperture or by using "Rattlesnaking" mode where aperture is closed down in bright light (cannot be turned on via settings other than going to Movie mode for shooting stills or pointing the camera towards flickering lights in PASM for some seconds). Also using Full Time AF may or may not help keep potential faces within the DOF where the camera can discern the face.

  • Light conditions and exposure compensation can have an impact. Manual exposure compensation can change Live View's exposure and thus make a face visible to FD that before was too much in shadows.

  • When FD does not detect any eyes it more often than not seems to focus on the middle of the face box, which unfortunately usually is the nose and thus may leave the eyes out of focus. Sometimes it aims in between the eyes, which is a far better position.

  • FD on the E-M5 does not like eyebrows being covered (which often happens by top-hair), mouth covering is another big problem, one eye covered is less of a problem.

  • You need to watch out when FD is enabled in shots where you don't want to use it, because it too often detects faces in areas that don't even closely resemble faces. This is a problem, because FD in combination with Evaluative metering will switch to spot metering on spot of the detected face as soon as any face is detected.

  • One way of getting better face detection might be to use Movie mode (for stills shooting) where A and M fix the aperture at your manually set up F-stop even during Live View (no separate DOF preview button needed). This would allow to dial in a slower aperture for more depth of field while aiming.

Main drawback is the lack of some Live View info screen (Highlight & Shadows) and the Live View image will have 5% cut away from all corners while the image remains uncut.

  • When Face Detection detects a face and evaluative metering is used than exposure metering meters on the spot of the detected face.

(end of part 2, part 3 in 2nd reply)

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Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: E-M5: Focusing explained
3

(part 3)

Focus Area priority

The focus frame only seems to be a priority area, but it is lower priority than a more fundamental function of the E-M5 focus. The E-M5 tries to stay close to its current plane of focus for as long as possible, even if that means to focus outside the focus area!

The advantage of this approach is that it doesn't hunt back and forth when you are focusing on more or less the same object/distance and thus acquires focus faster (less focus motor movement) and more reliable on the same object/distance when two focal planes are within the focus area.

Here is an example of my Fujifilm X10 that hunts for a new focal plane every time you half-press the shutter button. This not only leads to focus taking longer, but also to the camera deciding on a different focal plane (or failing) every time you have a second focal planes even just touching the focus area (focus area was set one step to the left, not dead center).

The disadvantage of the E-M5's approach is that sometimes you have to move the focus area considerably further towards another focal plane to make the E-M5 hunt for a new focal plane. For the central AF area this may be as far as the larger area shown by the 3x3 (golden rule) grid when the AF area itself has long been away from the original object/distance.

Center AF, AF-S, not recomposed:

Here is another example of how your initial focal plane can very much affect what is inside the AF box. The camera was not moved in between these shots (other than hand-shake).

When 9 or 35 focus areas are used then the same logic is applied, so you do not always get the closest contrasty object in focus, but the camera will shift the active focus area in order to maintain the plane of focus you last focused on. Only once the original plane of focus shifts out of the frame will the E-M5 hunt for a new focus plane and then often decide on the closest contrasty objects. You can test that by focusing out of an open window and then more and more turn toward the window frame with each shutter half-press.

(the end)

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RoelHendrickx
RoelHendrickx Forum Pro • Posts: 26,346
Thank you.

1. I will read through all of that more carefully later.

2. If you turn this into an Article (which I think would be a good thing), may I suggest that you make hyperlinks (both directions) between this article and the general one on setting up the E-M5 (which I found very useful as well).

3. And finally : two remarks on face detection.

3.a. I've only used it sparingly so far, but it actually seems to work pretty well and can be a good alternative for focus-recompose, especially with shallow DOF. Moving the focus box around with the arrow keys, OTOH is also quite intuitive. I am starting to use that more and more, with hands on camera and eye pressed to EVF, as an alternative for my usual focus-recompose, when the recompose could result in a shift in the focus (especially with extremely shallow DOF).

3.b. How you also experienced that face detection can sometimes regard and treat very peculiar shapes and patterns as if they are faces. I've noticed this when at one time I had FD turned on and forgot afterwards to turn it off. I've had it "detect" a large watermelon as a "face", but also a house in a landscape where two windows above a door in the middle of a fairly rectangular wall, were mistaken for eyes and mouth.

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apekkpul Contributing Member • Posts: 961
Findings & recommendations

A great article, thank you!

I would be nice if you could summarize your recommendations, just to ensure that people could utilize this information.

Pekka

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3DrJ Senior Member • Posts: 1,027
Re: Thank you.

RoelHendrickx wrote:

1. I will read through all of that more carefully later.

2. If you turn this into an Article (which I think would be a good thing), may I suggest that you make hyperlinks (both directions) between this article and the general one on setting up the E-M5 (which I found very useful as well).

3. And finally : two remarks on face detection.

3.a. I've only used it sparingly so far, but it actually seems to work pretty well and can be a good alternative for focus-recompose, especially with shallow DOF. Moving the focus box around with the arrow keys, OTOH is also quite intuitive. I am starting to use that more and more, with hands on camera and eye pressed to EVF, as an alternative for my usual focus-recompose, when the recompose could result in a shift in the focus (especially with extremely shallow DOF).

3.b. How you also experienced that face detection can sometimes regard and treat very peculiar shapes and patterns as if they are faces. I've noticed this when at one time I had FD turned on and forgot afterwards to turn it off. I've had it "detect" a large watermelon as a "face", but also a house in a landscape where two windows above a door in the middle of a fairly rectangular wall, were mistaken for eyes and mouth.

The last issue (3.b.) is something I've noticed quite often on the EM-5, and find it quite annoying. Unless I'm doing portraiture specifically, I usually disable it because it throws off the focus I've carefully tried to establish. I'd rather stick to the selected focus box since it's more predictable for subjects which are not dedicated portraits.

I'm imaging this is a hard problem to solve in terms of the algorithms used to implement face detection. (That would be a challenging program to write.) I'm not really sure, but it almost seems this has gotten more problematic since the EP3, which has a similar feature.

JRA

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acahaya
acahaya Senior Member • Posts: 1,174
Re: E-M5: Focusing explained
1

Thanks, good article and for sure very helpful for E-M5 owners.

Regarding Release Priority, not sure if this is a typo.

When using release priority On, the cam will fire, no matter if focus is achieved or not. This is the nature of release priority.

With release priority Off (i.e. focus priority), the cam will fire only if the green dot indicates that focus was found. In reality, this is unfortunately not 100% reliable, sometimes the green dot stops blinking but nothing in the focus box is in focus. If you have activated the focus beep and wait for the beep, it is reliable (although the beep is annoying). My conclusion so far is that the beep is determined by a different algorithm than the green dot and i'm using the beep for focus confirmation.

Regarding face detection:

A very practical feature not only for snapshots but with closer eye detection also for portraits with shallow DOF but you need to wait until the green rectangle appears and make sure it appears exactly where you want it to be.

The white frame only shows where the cam thinks it found a face and it sometimes finds faces in very interesting places

Furthermore face detection overrules your chosen focus field. It should be set to Off unless you really want to use it.
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Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: Thank you.

RoelHendrickx wrote:

2. If you turn this into an Article (which I think would be a good thing), may I suggest that you make hyperlinks (both directions) between this article and the general one on setting up the E-M5 (which I found very useful as well).

The DPR article was written by Richard Butler with additional input from me, so I have no real access to it. I can ask him if he finds time to look over it, but the DPR guys are very busy reviewing loads of cameras and sometimes going on holiday, too.

3.a. I've only used it sparingly so far, but it actually seems to work pretty well and can be a good alternative for focus-recompose, especially with shallow DOF. Moving the focus box around with the arrow keys, OTOH is also quite intuitive. I am starting to use that more and more, with hands on camera and eye pressed to EVF, as an alternative for my usual focus-recompose, when the recompose could result in a shift in the focus (especially with extremely shallow DOF).

Unfortunately the detection algorithm is worse than that of my Fujifilm X10, partly due to DOF, but also partly due to the E-M5 really having a hard time recognizing faces. I once pointed the E-M5 + 45/1.8 directly at my wife's face, filling a good part of the screen, prefocused on the face's plane and having her look straight into the camera and the E-M5 would not recognize it at all. Then I asked her to lift her hair (fringe?) away from her eye-brows and now the face was recognized. My boy has rather blond eye-brows on white skin and often the camera seems to fight with that, too. The X10 also seems better recognizing faces from the side.

3.b. How you also experienced that face detection can sometimes regard and treat very peculiar shapes and patterns as if they are faces. I've noticed this when at one time I had FD turned on and forgot afterwards to turn it off. I've had it "detect" a large watermelon as a "face", but also a house in a landscape where two windows above a door in the middle of a fairly rectangular wall, were mistaken for eyes and mouth.

Today it detected an USB plug (pointing towards the camera) as a face. I had some very weird example of what the camera thought to be faces. Here is just one example.

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RoelHendrickx
RoelHendrickx Forum Pro • Posts: 26,346
"Encyclopedia" (ahum)

Timur Born wrote:

RoelHendrickx wrote:

2. If you turn this into an Article (which I think would be a good thing), may I suggest that you make hyperlinks (both directions) between this article and the general one on setting up the E-M5 (which I found very useful as well).

The DPR article was written by Richard Butler with additional input from me, so I have no real access to it. I can ask him if he finds time to look over it, but the DPR guys are very busy reviewing loads of cameras and sometimes going on holiday, too.

OK, but I don't think Richard would mind putting a link at the bottom of his article to other related articles by his co-author. And you can always put a link to his article. That would be a good way to create an "encyclopedia" of knowledge on the E-M5.
I guess you are contemplating a "rattlesnaking" article too?

3.a. I've only used it sparingly so far, but it actually seems to work pretty well and can be a good alternative for focus-recompose, especially with shallow DOF. Moving the focus box around with the arrow keys, OTOH is also quite intuitive. I am starting to use that more and more, with hands on camera and eye pressed to EVF, as an alternative for my usual focus-recompose, when the recompose could result in a shift in the focus (especially with extremely shallow DOF).

Unfortunately the detection algorithm is worse than that of my Fujifilm X10, partly due to DOF, but also partly due to the E-M5 really having a hard time recognizing faces. I once pointed the E-M5 + 45/1.8 directly at my wife's face, filling a good part of the screen, prefocused on the face's plane and having her look straight into the camera and the E-M5 would not recognize it at all. Then I asked her to lift her hair (fringe?) away from her eye-brows and now the face was recognized. My boy has rather blond eye-brows on white skin and often the camera seems to fight with that, too. The X10 also seems better recognizing faces from the side.

3.b. How you also experienced that face detection can sometimes regard and treat very peculiar shapes and patterns as if they are faces. I've noticed this when at one time I had FD turned on and forgot afterwards to turn it off. I've had it "detect" a large watermelon as a "face", but also a house in a landscape where two windows above a door in the middle of a fairly rectangular wall, were mistaken for eyes and mouth.

Today it detected an USB plug (pointing towards the camera) as a face. I had some very weird example of what the camera thought to be faces. Here is just one example.

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Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: E-M5: Focusing explained

acahaya wrote:

Thanks, good article and for sure very helpful for E-M5 owners.

Thanks for the thumbs up!

Regarding Release Priority, not sure if this is a typo.

Could you please quote the part you mean. I know that Release priority "OFF" is meant to keep the camera from shooting out of focus, so everything I wrote should be what I meant (i.e. AF-C always showing a solid green dot even while the camera keeps hunting back and forth and thus allowing out of focus shots).

If you have activated the focus beep and wait for the beep, it is reliable (although the beep is annoying). My conclusion so far is that the beep is determined by a different algorithm than the green dot and i'm using the beep for focus confirmation.

My ouf-of-focus example image above was shot after the beep. So the beep is quicker (and thus more reliable for moving targets/camera), but not foolproof either.

Furthermore face detection overrules your chosen focus field. It should be set to Off unless you really want to use it.

Not only that, but with Evaluative metering is also overrules your chosen metering (Evaluative) and replaces it with weighted Spot metering on spot of the green frame. The latter includes all those instances where false faces are detected. I wrote "weighted Spot", because its weight seems to be a mixture of what Center Weighted and Spot gives you (at least as far as I remember from past tests).

I just evaluated something really important to understand. In combination with Evaluative metering the E-M5 meters inside the white box area whenever a face is detected, even when the face is not in focus! Furthermore it falls back to full Evaluative when no face is detected. And since the camera tends to detect face on and off whenever something changes in the scene (people moving, light changing, DOG) you can end up with unexpected metering results.

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Starred Regular Member • Posts: 375
Re: "Encyclopedia" (ahum)

A big thank you for your effort!

Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: Findings & recommendations

apekkpul wrote:

A great article, thank you!

Thanks in return!

I would be nice if you could summarize your recommendations, just to ensure that people could utilize this information.

I am not sure yet what my recommendations would be. My current though:

  • Some people here stated that Face Detection should be turned off, but despite my own warnings I found that in practice it more often does not detect faces than that it does and thus I usually leave it running all the time. But I am mostly shooting people anyway.

  • For AF-S in general and Face Detection in particular it is important to pre-focus when possible ("Full Time AF" may help). This will shift the DOF/focus plane to what you want to focus on in the final shot and thus better guarantee to hit the right focal plane.

Adding to the latter: I found that with AF-S I mostly get ouf-of-focus shots with wrongly lit green dot when the camera had to shift focal plane from one extreme to the other. A second half-press of the shutter usually solves that problem, so pre-focusing should avoid these situations as well.

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RoelHendrickx
RoelHendrickx Forum Pro • Posts: 26,346
Timur

Timur Born wrote:

acahaya wrote:

Thanks, good article and for sure very helpful for E-M5 owners.

Thanks for the thumbs up!

Regarding Release Priority, not sure if this is a typo.

Could you please quote the part you mean. I know that Release priority "OFF" is meant to keep the camera from shooting out of focus, so everything I wrote should be what I meant (i.e. AF-C always showing a solid green dot even while the camera keeps hunting back and forth and thus allowing out of focus shots).

I think he referred to this passage from your text:

Release Priority is just a "priority" option, especially in AF-C it still allows to release the shutter even when the image is not in focus (during AF-C hunting that only settles after a few seconds). Sometimes the camera signals false "in focus" even in AF-S and thus lets you take out of focus shots.

And I agree with him that it would be clearer if you wrote :

"Release Priority Off " is just a "priority" option, especially in AF-C it still allows to release the shutter even when the image is not in focus (during AF-C hunting that only settles after a few seconds). Sometimes the camera signals false "in focus" even in AF-S and thus lets you take out of focus shots.

If you write about an option, people are going to assume you mean it to be in the "ON" position. In the "ON" position, you can always force the shot, regardless of focus, so it does not make much sense posting a warning. The warning is useful for the "OFF" position, because some people might assume it will avoid all out-of-focus shots.
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Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: "Encyclopedia" (ahum)

RoelHendrickx wrote:

OK, but I don't think Richard would mind putting a link at the bottom of his article to other related articles by his co-author. And you can always put a link to his article. That would be a good way to create an "encyclopedia" of knowledge on the E-M5.

If I can reach him, then I think that should be possible. Amadou also put a link to my X10 article ("Summary of X10 functions and issues") into his X10 review as a result of me sharing information with him.

http://www.dpreview.com/articles/3785306838/summary-of-fujifilm-x10s-functions-and-issues

I guess you are contemplating a "rattlesnaking" article too?

Since "Rattlesnaking" seems to be very closely connected to metering and focus I thought to put it all together into one. Maybe I will also add my list of about 2 dozens issues and quirks (which I already put together like 2 months ago).

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Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: Thank you.

3DrJ wrote:

I'm imaging this is a hard problem to solve in terms of the algorithms used to implement face detection. (That would be a challenging program to write.) I'm not really sure, but it almost seems this has gotten more problematic since the EP3, which has a similar feature.

The X10 lacks the eye detection, but in return I cannot remember it ever detection a face in places that do not even closely resemble one (including holding both the X10 and E-M5 towards the same objects). So it can be done.

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Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: Timur

RoelHendrickx wrote:

I think he referred to this passage from your text:

She's a woman, albeit I admit that the forum pseudonym does not necessarily reveal that.

And I agree with him that it would be clearer if you wrote :

"Release Priority Off " is just a "priority" option, especially in AF-C it still allows to release the shutter even when the image is not in focus (during AF-C hunting that only settles after a few seconds). Sometimes the camera signals false "in focus" even in AF-S and thus lets you take out of focus shots.

Ah, yes, I understand and you are both right. I also should change that monster of a parenthesis sentence about AF-C. Will change both before putting it together in an article.

I admit that I somewhat lack the energy and time involved to write a good - as in enjoyable to read - article, especially as English is not my native language. That is why I keep these user articles to summaries and lists. Everyone can get the information out if they like or just leave it at that if they don't want to go through it.

Personally I was quite surprised myself that the AF area/frame is prioritized lower, this even affects full-screen "Zoom AF" where I can make the whole of the zoomed LV be out of focus because focus was kept on the former plane of focus outside the AF frame by the E-M5. This also was the reason why evaluating how Zoom AF works was a bit hard to come by. The specs list "800 AF points" for when Face Detection, and thus Zoom (Frame) AF are used.

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acahaya
acahaya Senior Member • Posts: 1,174
Re: Timur

The He is a She, otherwise you got it exactly right. I assumed Timur was talking about Release Prio On where release even without confirmed focus is the default.

Sabine
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assaft
assaft Senior Member • Posts: 1,424
Re: E-M5: Focusing explained

Thanks for this great post. And also for the other ones that were spread in different threads. I think that's a good idea to collect the information into an article. Maybe a wiki page that eventually grows to a kind of 'encyclopedia' would also be convenient, but probably that's not an option on dpreview. There are tons of discoveries and tips in dozens of threads and they can't be organized collectively and incrementally.

I wish I could read your article yesterday; I was shooting moving subjects with my e-pl2 and 45/1.8 - a camera that is of course slower than the e-m5 to begin with - and had some hard time (re-)focusing on faces. I can sum it up in some points:

  • In general I pre-focused on the face area even before I wanted to take the picture or before the camera recognized it as a face. As you wrote, this helps to acquire focus faster in the right moment.

  • If the camera recognizes the face then I refocus. Problem is that the face might be still moving and I'm waiting for a better moment. So using the C-AF could be helpful. I didn't think about that.

  • There is an annoying issue that when the focus frame box is activated it overrides the face recognition (although the white box is still shown) until the box is deactivated. There is not way to change this or to use another button to tell the camera to favor the recognized face for focusing. Since the face recognition doesn't always work, especially when people move and don't look straight at the camera, I sometimes had to switch back and forth between the box option and the face recognition.

In relation to metering I found that the metering modes can be quite tricky for moving subjects when exposing for the face. (what I write here is based on the e-pl2, I assume that things are pretty much the same on the e-m5.)

  • The evaluative mode would give the right exposure only if the camera recognized the face (and it's not important where the face is in the frame).

  • The center-weighted/spot modes would give the right exposure only if the subject is in the center of the frame (white box of recognized face is ignored) so it's necessary to meter the face and recompose.

When the subject moves it usually won't be recognized persistently so evaluative mode is hard to use. But it's also hard to keep the face constantly in the center of the frame. The best solution I came up with is this:

  • I set exposure to mode 3 and use Center-weighted / spot mode.

  • Lock the focus and exposure on the face of the subject, which has to be in the center of the frame. This requires two buttons - one for focusing and one for metering. Face recognition can help to focus but it's not crucial.

  • If the subject moves, there are three options: 1 - just to refocus, 2 - just to re-meter, 3 - both. Option 1 is useful if the subject moved from the center and requires re-focusing but the face is still under the same light. Re-metering would hurt the exposure for the face obtained before, so I only re-focus. Option 2 is useful if only the light on the face changed, refocusing can steal some important moments so if it can be avoided that's better. Option 3 is last resort when both focus and exposure have to be re-locked, so this takes me back to the previous step.

One thing to remember is that the exposure mode is set separately for S-AF and C-AF (i.e. modes 1/2/3).

Thanks again for the post.

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SkiHound Veteran Member • Posts: 3,456
Re: E-M5: Focusing explained

Thanks for putting this all together! I'd like to see this as an article as well. Will take me some time to digest.

Timur Born
OP Timur Born Veteran Member • Posts: 4,778
Re: Timur

I copy and pasted these bit out of other threads, so the Shutter Release Priority "OFF" part got lost (was part of the discussion in one of the threads). Good that I put this up for discussion here before making it into an article.

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