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Preferred Auto-Focus Mode?



 
 
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  #1  
Old September 9th 08, 01:07 AM posted to rec.photo.digital
DudeBoyz
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Posts: 38
Default Preferred Auto-Focus Mode?

In look at my camera, I see these four Auto-Focus modes
available:

- Face Detect
- iESP
- SPOT
- AREA

I find that I prefer to use SPOT, because it is often hard to get
the auto-focus to target on the specific object you want it to
focus on if there is much else around it.

AREA is sort of like SPOT, but I prefer to do an auto-focus with
SPOT and then frame the picture while holding the shutter button
half-way down, finally pressing the shutter button all the way
down.

I was wondering if the preference for SPOT on my part is heavily
in the minority, or if other folks still prefer to not give up
the farm and go fully-auto.

So, if you would, I'd appreciate replies specifying what is
preferred and why that method is preferred.

Thank you,

DB


  #2  
Old September 9th 08, 02:25 PM posted to rec.photo.digital
[email protected]
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Posts: 222
Default Preferred Auto-Focus Mode?

DudeBoyz wrote:
In look at my camera, I see these four Auto-Focus modes
available:

- Face Detect
- iESP
- SPOT
- AREA


I was wondering if the preference for SPOT on my part is heavily
in the minority, or if other folks still prefer to not give up
the farm and go fully-auto.



I have the Canon 30D, and use center spot. This is really center-area ...
it is three times bigger than the marked square, and the
area is much too big.

Before I got this, my first auto-focus camera, I had always
wondered how well autofocus could work for general scenes.
Sure, if it all is at infinity, or is flat, perpendicular
to the line of sight, it should work. But otherwise,
how does it tell what to focus on? Well, I was right to
worry. I usually have to focus on one spot and then reorirnt
the camera to get the proper framing. Even then, sometimes
it gets it wrong.

Doug McDonald
  #3  
Old September 9th 08, 02:41 PM posted to rec.photo.digital
James Silverton
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Posts: 155
Default Preferred Auto-Focus Mode?

lid wrote on Tue, 09 Sep 2008 08:25:12 -0500:

DudeBoyz wrote:
In look at my camera, I see these four Auto-Focus modes available:

- Face Detect
- iESP
- SPOT
- AREA

I was wondering if the preference for SPOT on my part is
heavily in the minority, or if other folks still prefer to
not give up the farm and go fully-auto.

I have the Canon 30D, and use center spot. This is really
center-area ... it is three times bigger than the marked
square, and the area is much too big.


Before I got this, my first auto-focus camera, I had always
wondered how well autofocus could work for general scenes.
Sure, if it all is at infinity, or is flat, perpendicular
to the line of sight, it should work. But otherwise,
how does it tell what to focus on? Well, I was right to
worry. I usually have to focus on one spot and then reorirnt
the camera to get the proper framing. Even then, sometimes
it gets it wrong.



Depending on the resolution of your camera, there must be a smallest
area in a viewfinder that can be used for passive ( not light beam
reflection) autofocus. A computer algorithm is used to decide on the
optimum value of some function and must have enough pixel values to
reliably calculate. I have wondered about the various functions. How for
example does the Nikon "Museum Mode" work when it takes 12 non-flash
pictures and decides on the "best"? It is often quite effective.
--

James Silverton
Potomac, Maryland

Email, with obvious alterations: not.jim.silverton.at.verizon.not

  #4  
Old September 9th 08, 05:40 PM posted to rec.photo.digital
Dave Martindale
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Posts: 438
Default Preferred Auto-Focus Mode?

"DudeBoyz" writes:
In look at my camera, I see these four Auto-Focus modes
available:


- Face Detect
- iESP
- SPOT
- AREA


I find that I prefer to use SPOT, because it is often hard to get
the auto-focus to target on the specific object you want it to
focus on if there is much else around it.


AREA is sort of like SPOT, but I prefer to do an auto-focus with
SPOT and then frame the picture while holding the shutter button
half-way down, finally pressing the shutter button all the way
down.


Yes, that's how I work too. I want to control what the camera focuses
on. Most of the other modes are intended for single-aim snapshooting:
you frame the picture the way you want, and the camera takes a bunch of
autofocus readings (one at each place there is a sensor) and "magically"
selects which one to use for adjuting the lens (often, the magic
algorithm is "take the closest point you found").

I was wondering if the preference for SPOT on my part is heavily
in the minority, or if other folks still prefer to not give up
the farm and go fully-auto.


I think full-auto is for people who don't want to worry about operating
the camera (e.g. you loan it to your grandmother for a few shots), or
when you expect you will not have time to do anything else.

I *can* see selecting a single focus point that is not in the centre, if
you know you want to track a moving object but you don't want that
object to be framed in the centre of the image.

Dave
  #5  
Old September 9th 08, 06:44 PM posted to rec.photo.digital
DudeBoyz
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Posts: 38
Default Preferred Auto-Focus Mode?

I usually have to focus on one spot and then reorirnt
the camera to get the proper framing. Even then, sometimes
it gets it wrong.

Doug McDonald


I'm much like you in technique then. Most of the time, shots
turn out fine when I'm framing a pic. But with this particular
model, I need to pull back just a bit from the full 20x zoom
range in order to get the type of results I'm used to getting.

Thanks for the reply.


  #6  
Old September 9th 08, 06:53 PM posted to rec.photo.digital
DudeBoyz
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Posts: 38
Default Preferred Auto-Focus Mode?

Yes, that's how I work too. I want to control what the camera
focuses on. Most of the other modes are intended for
single-aim snapshooting: you frame the picture the way you
want, and the camera takes a bunch of autofocus readings (one
at each place there is a sensor) and "magically" selects which
one to use for adjuting the lens (often, the magic algorithm
is "take the closest point you found").

I was wondering if the preference for SPOT on my part is
heavily in the minority, or if other folks still prefer to
not give up the farm and go fully-auto.


I think full-auto is for people who don't want to worry about
operating the camera (e.g. you loan it to your grandmother for
a few shots), or when you expect you will not have time to do
anything else.

I *can* see selecting a single focus point that is not in the
centre, if you know you want to track a moving object but you
don't want that object to be framed in the centre of the image.


Thanks for the reply. Instead of Auto, I usually use this mode:

"P - Set the optimum aperture value and shutter speed for the
brightness of the subject."

I don't change much from the default settings, but this mode
seems to give me more options from which to choose.

My father used to have an old Pentax that had this very cool
focusing dot in the middle of the viewfinder. I'm talking some
20+ years back. It was sort of "divided" into two areas and you
set the focus with the ring until those two areas were crystal
clear. It worked incredibly well, and the light meter thing on
the side of the viewfinder showed you what your shutter speed
was, I think.

I certainly wish that the EVF in today's point and shoot type of
cameras had that focus feature.

Thanks again for your reply.

Happy Snappin'!



  #7  
Old September 9th 08, 10:12 PM posted to rec.photo.digital
Blinky the Shark
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Posts: 827
Default Preferred Auto-Focus Mode?

James Silverton wrote:

lid wrote on Tue, 09 Sep 2008 08:25:12 -0500:

DudeBoyz wrote:
In look at my camera, I see these four Auto-Focus modes available:

- Face Detect
- iESP
- SPOT
- AREA

I was wondering if the preference for SPOT on my part is
heavily in the minority, or if other folks still prefer to
not give up the farm and go fully-auto.

I have the Canon 30D, and use center spot. This is really
center-area ... it is three times bigger than the marked
square, and the area is much too big.


Before I got this, my first auto-focus camera, I had always
wondered how well autofocus could work for general scenes.
Sure, if it all is at infinity, or is flat, perpendicular
to the line of sight, it should work. But otherwise,
how does it tell what to focus on? Well, I was right to
worry. I usually have to focus on one spot and then reorirnt
the camera to get the proper framing. Even then, sometimes
it gets it wrong.



Depending on the resolution of your camera, there must be a smallest
area in a viewfinder that can be used for passive ( not light beam
reflection) autofocus. A computer algorithm is used to decide on the
optimum value of some function and must have enough pixel values to
reliably calculate. I have wondered about the various functions. How for
example does the Nikon "Museum Mode" work when it takes 12 non-flash
pictures and decides on the "best"? It is often quite effective.


James, I can't find anything on Museum Mode taking a dozen shots. Can you
help me with a link to a discussion about that? Thanks.


--
Blinky
Killing all posts from Google Groups
The Usenet Improvement Project:
http://improve-usenet.org
Need a new news feed? http://blinkynet.net/comp/newfeed.html

  #8  
Old September 9th 08, 11:00 PM posted to rec.photo.digital
Alan Browne
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Posts: 12,640
Default Preferred Auto-Focus Mode?

DudeBoyz wrote:

So, if you would, I'd appreciate replies specifying what is
preferred and why that method is preferred.


Manual. 'Cuz I take my time. And that's a good thing.

Practically, when I do use AF, I find centered is easiest. Point,
focus, lock (half-depressed shutter release) re-compose, shoot.

However, mixing AE modes and the above is tricky. On my cameras that is
usually 'hold AEL' for the exposure lock and hold the shutter
half-depressed for the focus lock. Also why I shoot manual exposure a lot.


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  #9  
Old September 10th 08, 12:37 AM posted to rec.photo.digital
DudeBoyz
external usenet poster
 
Posts: 38
Default Preferred Auto-Focus Mode?

Thanks for the reply. It's helpful.

DudeBoyz wrote:

So, if you would, I'd appreciate replies specifying what is
preferred and why that method is preferred.


Manual. 'Cuz I take my time. And that's a good thing.

Practically, when I do use AF, I find centered is easiest.
Point, focus, lock (half-depressed shutter release) re-compose,
shoot.

However, mixing AE modes and the above is tricky. On my
cameras that is usually 'hold AEL' for the exposure lock and
hold the shutter half-depressed for the focus lock. Also why
I shoot manual exposure a lot.



  #10  
Old September 10th 08, 05:18 PM posted to rec.photo.digital
Olin K. McDaniel[_2_]
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Posts: 36
Default Preferred Auto-Focus Mode?

On Tue, 09 Sep 2008 18:00:11 -0400, Alan Browne
wrote:

DudeBoyz wrote:

So, if you would, I'd appreciate replies specifying what is
preferred and why that method is preferred.


Manual. 'Cuz I take my time. And that's a good thing.

Practically, when I do use AF, I find centered is easiest. Point,
focus, lock (half-depressed shutter release) re-compose, shoot.

However, mixing AE modes and the above is tricky. On my cameras that is
usually 'hold AEL' for the exposure lock and hold the shutter
half-depressed for the focus lock. Also why I shoot manual exposure a lot.


This topic is rather broad, since it's not pertinent to a specific
brand of camera. I've used the Nikon D300 a little, but am using my
own Pentax K10D where I find the AF.C (autofocus continuous) is my
choice. When I shoot Hummingbirds at my feeders, I focus on a flower
stalk poked in the feeder of choice, then remove it and wait for a
bird to arrive. I then shoot with a remote button so as NOT to half
press the shutter button and mess up my focus. Now, you might suggest
I should just wait and do a Manual focus. After hundreds of attempts,
I find I'm never able to get as sharp a focus in Manual as the camera
can in the method just described. To clarify - I'm using a Sigma 180
mm Macro lens at a distance of about 5 feet. I've never understood
why the camera can do so much better focusing than can I, but it's got
me convinced. And this is true regardless of whether I use Spot
(Center) or Auto (its choice of 1 of 11 points).

Olin McDaniel

To reply by email, please remove "abcd" from Return address
-----------------------------------------------------
"Ignorance is treatable, Stupidity is incurable. Sometimes
the difference is hardly distinguishable, however."
 




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