D7 Tracking Autofocus Problems...

[Geir Ove]

Hello,

I posted part of this message in another thread, but maybe the question drowned in the other info, trying again in a separate thread (this is an issue...)

I have used my D7 for a week now, and overall I am very pleased with the camera. I love the EVF, the controls, and the features available! However, there is an autofocus issue (as Phil correctly reported)

Autofocus

Single** Shot AF works fairly well. It has its problems now and then, especially if one sits down and tries to find a spot where the camera will not focus.. But my CoolPix 950 is much worse....
Among the 35 pictures I took yesterday, I did not encounter any AF problems.

However Continous (Tracking) Mode AF does not work on my sample (Firmware A1v021e). The Continous AF is never able to achieve final focus even when pointing the camera at a stationary object: The AF "hunts" back and forth (very quickly), and the image goes in and out of focus. When taking picture in this mode, you may be lucky to hit the release button when the subject temporarily is in focus, but most pictures will be blurred

How many others has this problem?

NOTE: The "Sports" Program uses Continous AF. In the P mode, you must turn it on in the Basic Menu.

Geir Ove

 

[Bryan Biggers]

I think that it works OK.
Here is what I wrote on my web page... see what you think.

The continuous autofocus mode is spooky. I Think that it
works... but sometimes I'm not sure! When you select it, the
focus seems to seek in and out constantly, and still takes just
as long to focus when you press the release. The big trick is
that you have to half press the shutter continuously to operate
it.

What seems to be happening is this...

When the camera does not have focus, it begins seeking in and
out with full travel of the lens taking about 1 second per pass.
During any pass it may lock on to an object. Once it has locked
on, it begins making smaller in and out focus movements,
trying to keep the object in focus. If the object does not move
too fast, the camera is able to track it quite well. When the
camera looses focus, it begins over with the full in and out
focus movements. This DOES work if you keep pointing the
camera in an intelligent way, following a running person, for
example. It works horribly if you swing the camera around
rapidly; the camera just does not have time to lock on and
keeps running the full focus cycles that take about a second. If
you swing the camera around so that there is a new subject in
the field every second, the camera will never be able to focus.
Once you get the feel for it, it is actually easy to use. The
critical time period is about a second or second and a half.
Once you loose focus, if your subject changes faster than that
time period (say kids running around like crazy close to the
camera, I tried that!), the camera will not be able to refocus. If
your subject moves slower than that (like runners at a track at
reasonable distance), then the mode works great.

The "Sports mode" is an interesting way to try continuous
focus. The way it works is that you half press, and start to
point the camera at whatever you are interested in. The
camera will go into continuous focus while you half press, and
when it gets focus the little focus indicator will turn White and
you can take a picture. If your subject moves, the indicator will
turn Red for a second, then White again as it regains focus. You
can't take a picture while the indicator is Red. This actually
works pretty well on things that are moving around.

What seems to happen on my camera is that yes, the focus is seeking in and out, which looks funny, but when you press the shutter the focus quickly returns to the last "good" spot and snaps the shot, then continues seeking. My shots have been good with it, I wonder if yours could have been blurry due to low shutter speed etc.? Bryan

Hello,

I posted part of this message in another thread, but maybe the
question drowned in the other info, trying again in a separate
thread (this is an issue...)

I have used my D7 for a week now, and overall I am very pleased
with the camera. I love the EVF, the controls, and the features
available! However, there is an autofocus issue (as Phil correctly
reported)

Autofocus
Single** Shot AF works fairly well. It has its problems now and
then, especially if one sits down and tries to find a spot where
the camera will not focus.. But my CoolPix 950 is much worse....
Among the 35 pictures I took yesterday, I did not encounter any AF
problems.

However Continous (Tracking) Mode AF does not work on my
sample (Firmware A1v021e). The Continous AF is never able to
achieve final focus even when pointing the camera at a stationary
object: The AF "hunts" back and forth (very quickly), and the image
goes in and out of focus. When taking picture in this mode, you may
be lucky to hit the release button when the subject temporarily is
in focus, but most pictures will be blurred

How many others has this problem?

NOTE: The "Sports" Program uses Continous AF. In the P mode, you
must turn it on in the Basic Menu.

Geir Ove

 

[Wayne DeWitt]

There is no focus tracking problem - it is working "as designed". See my thread for my opinion on this. In short - it's shifting focus anticipating movement. It is NOT the mode to use for general photography.

Wayne

Hello,

I posted part of this message in another thread, but maybe the
question drowned in the other info, trying again in a separate
thread (this is an issue...)

I have used my D7 for a week now, and overall I am very pleased
with the camera. I love the EVF, the controls, and the features
available! However, there is an autofocus issue (as Phil correctly
reported)

Autofocus
Single** Shot AF works fairly well. It has its problems now and
then, especially if one sits down and tries to find a spot where
the camera will not focus.. But my CoolPix 950 is much worse....
Among the 35 pictures I took yesterday, I did not encounter any AF
problems.

However Continous (Tracking) Mode AF does not work on my
sample (Firmware A1v021e). The Continous AF is never able to
achieve final focus even when pointing the camera at a stationary
object: The AF "hunts" back and forth (very quickly), and the image
goes in and out of focus. When taking picture in this mode, you may
be lucky to hit the release button when the subject temporarily is
in focus, but most pictures will be blurred

How many others has this problem?

NOTE: The "Sports" Program uses Continous AF. In the P mode, you
must turn it on in the Basic Menu.

Geir Ove

 

[Mark H]

Geir,

Although this defeats the object of 'sports mode/focus tracking', I expect you'll find that if the camera and subject are both stationary the focus will fix and stop hunting... do you?

I suspect that as soon as the camera or subject moves, the focus finding algorithm cannot differentiate between sideways movement and distance variation and so has to re-check focus. Combined with the likelyhood that the focus algorithm needs to first pass through and then reverse back to best focus, all whilst the subject is continually moving (or camera shaking), would seem to guarantee constant focus hunting.

Also the wide depth of focus of the short focal length lens probably means, perversely that the optics have to move further in their range to find poor focus in order to establish best focus.

So what's the point of continual focus tracking/sports mode then? I'm guessing... (I don't actually know, so perhaps you and others might confirm this) ...that where as in normal mode the camera does not release the shutter until focus is finished, in sports mode you might be able to follow your subject and fire the shutter without the focus delay, albeit probably not with very best focus?

As I said above, I don't know any of this for fact, 'though in twenty minutes of playing with a Nikon 880 at work recently I observed exactly the same behaviour.

I'd be interested to hear back from you and others re: any focus delay in the sports mode compared with the typical 1 second in normal mode?

Regards

Mark

 

[Mark H]

Just as I thought... it took me so long to compose my message, that somebody had provided an answer long before I posted my question!

Anyway... thanks Bryan

 

[Geir Ove]

I think you are rihgt!

I tested this again, and what I find is that the camera does not fire until it reaches focus in each "hunt". Each hunt lasts for about a 1 sec as you said. I took 15 pictures; 7 at 28mm inhouse on a tripod, and 7 outside at 150mm on a tripod: they all came out focused.

However, some the "hunt" cycles sometimes become quite long, and this delays the time when the actual picture is taken.

Geir Ove

 

[Mark H]

Hi Wayne,

Narrow range tracking I can believe, but predictive focusing?... I'd be amazed!

Cheers

Mark

 

[Mark H]

I don't quite follow... do you mean you were (slowly) panning the tripod?

 

[Bryan Biggers]

I think you are rihgt!
I tested this again, and what I find is that the camera does not
fire until it reaches focus in each "hunt". Each hunt lasts for
about a 1 sec as you said. I took 15 pictures; 7 at 28mm inhouse on
a tripod, and 7 outside at 150mm on a tripod: they all came out
focused.

However, some the "hunt" cycles sometimes become quite long, and
this delays the time when the actual picture is taken.

Yeah, this is true. It is sort of like it has two hunt modes. The first one is a "full focus" seek, and takes about a second. It uses this one when it has no idea where the focus is (like if you point the camera at something else). The second hunt mode is a "small seek" focus mode, where it jogs the lens back and forth around what it thinks the focus point is. As it does that, it looks at the best spot in that range, assuming that there is one, and uses that as the new focus setting. As long as your subject keeps within the little small focus seeks, it will be able to find a new focus spot for it. So if someone moves toward you slowly it will be able to "track" them moving. Cool, eh? If you press the shutter in one of the small focus seeks, it seeks back to the last in focus spot and fires the shutter. This is usually pretty quick, depending on how far it is from the last best focus spot, but there can be variation depending on where it is in the cycle.

However, sometimes if you move the camera too much, or your subject moves, then it has to start the "big" focus seeks again, and if you press the shutter during that time it takes a long time to shoot, probably as long as a full press of the shutter would normally take, at least a second. The spooky thing is that you don't always know what it is doing, (although the little in focus indicator in the EVF helps a lot, watch it out of the corner of your eye), so sometimes it is surprising when it takes a long time.

Bryan

Geir Ove

 

[Bryan Biggers]

Hi Wayne,

Narrow range tracking I can believe, but predictive focusing?...
I'd be amazed!

Cheers

Mark

That would be cool. Some of the Canon cameras have that feature. I don't know if this does it or not. It seems like it would not be hard to do, but it would only help with slowly moving things. All they would do in the simplest case is track how the "focus" point is moving while doing the small seeks, and bias them in that direction, seeking a little more in the direction in or out that the thing seemed to be moving. It would sound really cool in an ad anyway.
Bryan

 

[Wayne DeWitt]

It may be in fact what they do. Since it is always seeking when there is a change it will encounter it, measure the difference and shift the "scan width" a corresponding amount + a variable factor. I'll have to go play in traffic (finally taking free advice) and see what it really does. The manual is quite clear that it will not "lock" in this mode - the actual focus point is decided at the time the shutter trips, and unavailable for viewing.

Wayne

Hi Wayne,

Narrow range tracking I can believe, but predictive focusing?...
I'd be amazed!

Cheers

Mark

That would be cool. Some of the Canon cameras have that feature. I
don't know if this does it or not. It seems like it would not be
hard to do, but it would only help with slowly moving things. All
they would do in the simplest case is track how the "focus" point
is moving while doing the small seeks, and bias them in that
direction, seeking a little more in the direction in or out that
the thing seemed to be moving. It would sound really cool in an ad
anyway.
Bryan

 

[MikeA]

Speaking of auto-focusing...a friend tells me that a Minolta rep recommended leaving the camera in the mode whereby you can move the focusing spot -- the cross-hair -- and positioning the cross-hair dead center (and leaving it there). The rep claimed this can improve the speed of auto-focusing a bit.

Have you tried this? (I imagine it would take a while for the improvement, if there is any, to become apparent.)

It may be in fact what they do. Since it is always seeking when
there is a change it will encounter it, measure the difference and
shift the "scan width" a corresponding amount + a variable factor.
I'll have to go play in traffic (finally taking free advice) and
see what it really does. The manual is quite clear that it will not
"lock" in this mode - the actual focus point is decided at the time
the shutter trips, and unavailable for viewing.

 

[Wayne DeWitt]

I did, but didn't play with it too much. In the "wide field" autofocus I've noticed several different poitions and shapes to the illuminated box that indicates correct focus has been achieved. I haven't been able to detect a consistant pattern (some have said that it will always focus on the closest point in the frame - but that hasn't always been the case for me). In the "spot" mode you have only the crosshairs. When using the flex point focus it does seem that focus is achieved more rapidly - but I haven't used both for the same subjects so I can't state that it is a fact. If your subject has areas without detail the flex point may take longer, or fail to lock on at all, depending on where it's been placed. Since it is sensitive to placement I'll probably limit the flex point focusing to tripod use (at least 50% of my shooting) for the most part. Still experimenting though - there's a lot to this camera. As other threads have shown there's enough to confuse most people. I'm sure glad this isn't my first digicam, I'd be as confused as a snake with 2 heads.

Wayne

Have you tried this? (I imagine it would take a while for the
improvement, if there is any, to become apparent.)

It may be in fact what they do. Since it is always seeking when
there is a change it will encounter it, measure the difference and
shift the "scan width" a corresponding amount + a variable factor.
I'll have to go play in traffic (finally taking free advice) and
see what it really does. The manual is quite clear that it will not
"lock" in this mode - the actual focus point is decided at the time
the shutter trips, and unavailable for viewing.

 

[David Martin]

Wayne wrote:
As

other threads have shown there's enough to confuse most people. I'm
sure glad this isn't my first digicam, I'd be as confused as a
snake with 2 heads.

Wayne

Exactly Wayne. Theat's why i haven't bought one yet.
A snake with two heads (3 heads? No photographic experience? )
aka
DaveMart

 

[Tricia]

Ahem...Dave...the longer you wait to buy, the longer it will be until you're experienced! Go ahead...nudge, nudge...jump in. You have to start somewhere. Any other platitudes, anyone?

Tricia

Exactly Wayne. Theat's why i haven't bought one yet.
A snake with two heads (3 heads? No photographic experience? )
aka
DaveMart

 

[David Martin]

Tricia

Exactly Wayne. Theat's why i haven't bought one yet.
A snake with two heads (3 heads? No photographic experience? )
aka
DaveMart

Tricia,

For a comment such as you're not experienced yet but I think I can help I expect at least a wink wink as well as a nudge nudge......I'm sorry I really am a terminal case.......
Carry On,
DaveMart

 

[Tricia]

;-) ;-) Hopefully that's more encouraging! Come on, big guy...LOL

Really, if you're not experienced in photography, are you planning to buy a photography book or two? Or at least do some major online reading? This camera has so much to offer in the way of possibilities, it would be a shame not to take advantage of them...and that means learning all about light and F-stops and shutter speeds and depth of field and composition and...(besides, you can use it in full auto for a while).

Even if you bought a simpler camera, these things would still be important to help you get better pictures, unless you bought a really simple point-and-shoot digital...but then you'd have to keep upgrading every time you found that you needed for your next camera to have more control...just start and the top (in my price range, anyway)...thatta boy, I can just feel you getting closer...nudge, nudge...;-)

Tricia,
For a comment such as you're not experienced yet but I think I can
help I expect at least a wink wink as well as a nudge
nudge......I'm sorry I really am a terminal case.......
Carry On,
DaveMart

 

[David Martin]

Really, if you're not experienced in photography, are you planning
to buy a photography book or two? Or at least do some major online
reading? This camera has so much to offer in the way of
possibilities, it would be a shame not to take advantage of
them...and that means learning all about light and F-stops and
shutter speeds and depth of field and composition and...(besides,
you can use it in full auto for a while).

Even if you bought a simpler camera, these things would still be
important to help you get better pictures, unless you bought a
really simple point-and-shoot digital...but then you'd have to keep
upgrading every time you found that you needed for your next camera
to have more control...just start and the top (in my price range,
anyway)...thatta boy, I can just feel you getting closer...nudge,
nudge...;-)

Tricia,
For a comment such as you're not experienced yet but I think I can
help I expect at least a wink wink as well as a nudge
nudge......I'm sorry I really am a terminal case.......
Carry On,
DaveMart

Still no wink wink?
And what is LOL anyway?
Hey, I think I'll buy an E10 so I can just feel so much better than you guys.

Q: Does the E10 actually exist or is it purely a metaphorical expression for an elevated state of consciousness leading to a feeling of superiority which can actually be measured in units based on a logarithmic scale where infinity= 1 gonz?
Enough already.
See you soon,
DaveMart