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Hi,

I was wondering, what is the advantage of many autofocus points? When
I use autofocus on my 400D I sometimes have to hunt for a focus point
to focus at a particular point.. I often switch to manual selection of
which point that should be focused on... Is there a draw back to doing
this? why have 9 points? I think most of the time it tends to focus on
odd places like the hair or ears of a person, when I really want to
focus on the eyes..

Any clearafication is appreciated

Soren

"Soren" <> schreef in bericht
news: oups.com...
> Hi,
>
> I was wondering, what is the advantage of many autofocus points? When
> I use autofocus on my 400D I sometimes have to hunt for a focus point
> to focus at a particular point.. I often switch to manual selection of
> which point that should be focused on... Is there a draw back to doing
> this? why have 9 points? I think most of the time it tends to focus on
> odd places like the hair or ears of a person, when I really want to
> focus on the eyes..

I always use just the middle point, and when i want to focus on something
that's not in the middle i focus on it and change the position after that,
holding the shutter-release half pressed. maybe oldfashioned, but works
easiest.
Note that you have to use the appropiate setting: hence no servo-focussing.

Rutger


--
http://www.flickr.com/photos/zwaarddrager

"Soren" <> wrote in message
news: oups.com...
> Hi,
>
> I was wondering, what is the advantage of many autofocus points? When
> I use autofocus on my 400D I sometimes have to hunt for a focus point
> to focus at a particular point.. I often switch to manual selection of
> which point that should be focused on... Is there a draw back to doing
> this? why have 9 points? I think most of the time it tends to focus on
> odd places like the hair or ears of a person, when I really want to
> focus on the eyes..
>
> Any clearafication is appreciated
>
> Soren
>

Yes.

5, 7, 9, 11 point focussing is all part of the sales spiel for the techno
buyers who must have the highest spec. Of even less importance than the ever
increasing number of pixels.

If you know what you are doing, 1 focus point is all you need. I would
advocate only ever using 1 at a time, but it is sometimes convenient to
select an off centre point, so there is some justification for having more
than 1.

Roy G

Rutger wrote:
> "Soren" <> schreef in bericht
> news: oups.com...
>> Hi,
>>
>> I was wondering, what is the advantage of many autofocus points? When
>> I use autofocus on my 400D I sometimes have to hunt for a focus point
>> to focus at a particular point.. I often switch to manual selection of
>> which point that should be focused on... Is there a draw back to doing
>> this? why have 9 points? I think most of the time it tends to focus on
>> odd places like the hair or ears of a person, when I really want to
>> focus on the eyes..
>
> I always use just the middle point, and when i want to focus on something
> that's not in the middle i focus on it and change the position after that,
> holding the shutter-release half pressed. maybe oldfashioned, but works
> easiest.
> Note that you have to use the appropiate setting: hence no servo-focussing.
>
> Rutger

Many focus points are needed to be able to compose freely and have
the focal point where you want it. For example, when imaging wildlife
or people, a key to a great photo is focusing on the eyes.
Here is an example:

http://www.clarkvision.com/galleries...0240b-700.html

I used manual focus point selection, and AI servo. The AI servo tracks
focus as the subject moves toward or away from the camera, and even predicts
the rate of change and moves the focus to the predicted point when
the shutter actually fires, as opposed to when you press the button,
thus compensating for the shutter lag. If you just use center focus
all the time, focus would not be on the eyes, for example, in this shot:

http://www.clarkvision.com/galleries...8463b-700.html

During action, as I follow the action, I manually move the focus
point to keep an AF sensor on the eyes while maintaining the
composition I want. I use a 1D Mark II which has 45 AF points.
I wish it had more AF points!

Roger

On Apr 28, 6:59 am, "Rutger" <nos...@please.com> wrote:
> "Soren" <soren.skou.niel...@gmail.com> schreef in berichtnews: ooglegroups.com...
>
> > Hi,
>
> > I was wondering, what is the advantage of many autofocus points? When
> > I use autofocus on my 400D I sometimes have to hunt for a focus point
> > to focus at a particular point.. I often switch to manual selection of
> > which point that should be focused on... Is there a draw back to doing
> > this? why have 9 points? I think most of the time it tends to focus on
> > odd places like the hair or ears of a person, when I really want to
> > focus on the eyes..
>
> I always use just the middle point, and when i want to focus on something
> that's not in the middle i focus on it and change the position after that,
> holding the shutter-release half pressed. maybe oldfashioned, but works
> easiest.
> Note that you have to use the appropiate setting: hence no servo-focussing.
>
> Rutger
>
> --http://www.flickr.com/photos/zwaarddrager

I agree with Rutger, and find that its easier to do it that way than
to select which focus point I want to use.


Eric

On Apr 28, 2:33 pm, "Roger N. Clark (change username to rnclark)"
<usern...@qwest.net> wrote:
> Rutger wrote:
> > "Soren" <soren.skou.niel...@gmail.com> schreef in bericht
> >news: roups.com...
> >> Hi,
>
> >> I was wondering, what is the advantage of many autofocus points? When
> >> I use autofocus on my 400D I sometimes have to hunt for a focus point
> >> to focus at a particular point.. I often switch to manual selection of
> >> which point that should be focused on... Is there a draw back to doing
> >> this? why have 9 points? I think most of the time it tends to focus on
> >> odd places like the hair or ears of a person, when I really want to
> >> focus on the eyes..
>
> > I always use just the middle point, and when i want to focus on something
> > that's not in the middle i focus on it and change the position after that,
> > holding the shutter-release half pressed. maybe oldfashioned, but works
> > easiest.
> > Note that you have to use the appropiate setting: hence no servo-focussing.
>
> > Rutger
>
> Many focus points are needed to be able to compose freely and have
> the focal point where you want it. For example, when imaging wildlife
> or people, a key to a great photo is focusing on the eyes.
> Here is an example:
>
> http://www.clarkvision.com/galleries.../lion.c01.23.2...
>
> I used manual focus point selection, and AI servo. The AI servo tracks
> focus as the subject moves toward or away from the camera, and even predicts
> the rate of change and moves the focus to the predicted point when
> the shutter actually fires, as opposed to when you press the button,
> thus compensating for the shutter lag. If you just use center focus
> all the time, focus would not be on the eyes, for example, in this shot:
>
> http://www.clarkvision.com/galleries.../lion.c01.20.2...
>
> During action, as I follow the action, I manually move the focus
> point to keep an AF sensor on the eyes while maintaining the
> composition I want. I use a 1D Mark II which has 45 AF points.
> I wish it had more AF points!
>
> Roger

Thanks for all the answers everyone! So multiple AF points is really
good if you use the servo and track a motion and want to maintain a
certain composition. But for still photos I can use the center point
and move the camera (as I do now) without getting into trouble.

Thanks for the nice examples Roger, great pictures by the way!

Soren

Soren <> writes:

> certain composition. But for still photos I can use the center point
> and move the camera (as I do now) without getting into trouble.

Canon have recomended against this, and have said that for best AF
accuracy you should NOT focus and re-frame, but to use the AF point
in the best position.

In article <>, Paul Repacholi
<> wrote:

> Canon have recomended against this, and have said that for best AF
> accuracy you should NOT focus and re-frame, but to use the AF point
> in the best position.

They're full of ****.

On Sat, 28 Apr 2007 12:21:00 GMT, "Roy G"
<> wrote:

>
>"Soren" <> wrote in message
>news: roups.com...
>> Hi,
>>
>> I was wondering, what is the advantage of many autofocus points? When
>> I use autofocus on my 400D I sometimes have to hunt for a focus point
>> to focus at a particular point.. I often switch to manual selection of
>> which point that should be focused on... Is there a draw back to doing
>> this? why have 9 points? I think most of the time it tends to focus on
>> odd places like the hair or ears of a person, when I really want to
>> focus on the eyes..
>>
>> Any clearafication is appreciated
>>
>> Soren
>>
>
>Yes.
>
>5, 7, 9, 11 point focussing is all part of the sales spiel for the techno
>buyers who must have the highest spec. Of even less importance than the ever
>increasing number of pixels.
>
>If you know what you are doing, 1 focus point is all you need. I would
>advocate only ever using 1 at a time, but it is sometimes convenient to
>select an off centre point, so there is some justification for having more
>than 1.
>
>Roy G
>
That's true for static subjects etc. but for sports/photojournalism
etc. modern cameras use the multiple off-centre focus points to
(atempt to) lock onto a moving subject and keep it in focus even if it
is not kept within the same position within the frame.

Paul Repacholi wrote:
> Soren <> writes:
>
>> certain composition. But for still photos I can use the center point
>> and move the camera (as I do now) without getting into trouble.
>
> Canon have recomended against this, and have said that for best AF
> accuracy you should NOT focus and re-frame, but to use the AF point
> in the best position.
They are wrong. Using many focus points can lead to the classic sharp
wall behind the 2 foreground people's blurred faces.

Morton