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-   -   Olympus E5: 11-point TTL Phase Difference Detection (http://www.velocityreviews.com/forums/t956119-olympus-e5-11-point-ttl-phase-difference-detection.html)

Peter Jason 01-04-2013 02:57 AM

Olympus E5: 11-point TTL Phase Difference Detection
 
When I photograph a group of people, say 12, how
does the "11 point focus" know where to focus?
Does it go for the movement or does it average the
lot? There's no explanation in the manual.

Some cameras have far more than 11 "point focus
points".

Peter

RichA 01-05-2013 09:35 AM

Re: Olympus E5: 11-point TTL Phase Difference Detection
 
On Jan 3, 9:57*pm, Peter Jason <p...@jostle.com> wrote:
> When I photograph a group of people, say 12, how
> does the "11 point focus" know where to focus?
> Does it go for the movement or does it average the
> lot? * There's no explanation in the manual.
>
> Some cameras have far more than 11 "point focus
> points".
>
> Peter


How does 49 points know? How does 51? They don't. Which is why
letting the camera do the choosing, even when it averages them, is
often off the mark, especially with scenes with multiple DOF objects.

DanP 01-05-2013 11:48 AM

Re: Olympus E5: 11-point TTL Phase Difference Detection
 
On Friday, January 4, 2013 2:57:11 AM UTC, Peter Jason wrote:
> When I photograph a group of people, say 12, how
> does the "11 point focus" know where to focus?
> Does it go for the movement or does it average the
> lot? There's no explanation in the manual.


You'd be very lucky to have all focus points covering your subject(s).
Some will be sitting over the background.
It has to be a clever algorithm trying to guess what you want to do.

I only use the central focus point, half press and recompose the frame.
That way I get to focus where I decide. If I want to focus over a wider range I close the aperture. No guessing involved.

I don't like to use tools smarter than me, make me look stupid and not knowing what I am doing.


DanP

Peter 01-05-2013 11:19 PM

Re: Olympus E5: 11-point TTL Phase Difference Detection
 
On 1/5/2013 4:35 AM, RichA wrote:
> On Jan 3, 9:57 pm, Peter Jason <p...@jostle.com> wrote:
>> When I photograph a group of people, say 12, how
>> does the "11 point focus" know where to focus?
>> Does it go for the movement or does it average the
>> lot? There's no explanation in the manual.
>>
>> Some cameras have far more than 11 "point focus
>> points".
>>
>> Peter

>
> How does 49 points know? How does 51? They don't. Which is why
> letting the camera do the choosing, even when it averages them, is
> often off the mark, especially with scenes with multiple DOF objects.
>


For that type of shot I do not use autofocus! Instead I try to set a
hyper-focal distance, with an appropriate f stop. the problem is that
many of the ewer lenses, don't have the hyper-focal distance on the
barrel. In that case I apply "Kentucky windage."


--
PeterN

Peter Jason 01-06-2013 09:31 PM

Re: Olympus E5: 11-point TTL Phase Difference Detection
 
On Sat, 05 Jan 2013 18:19:08 -0500, Peter
<peter.new@verizon.net> wrote:

>On 1/5/2013 4:35 AM, RichA wrote:
>> On Jan 3, 9:57 pm, Peter Jason <p...@jostle.com> wrote:
>>> When I photograph a group of people, say 12, how
>>> does the "11 point focus" know where to focus?
>>> Does it go for the movement or does it average the
>>> lot? There's no explanation in the manual.
>>>
>>> Some cameras have far more than 11 "point focus
>>> points".
>>>
>>> Peter

>>
>> How does 49 points know? How does 51? They don't. Which is why
>> letting the camera do the choosing, even when it averages them, is
>> often off the mark, especially with scenes with multiple DOF objects.
>>

>
>For that type of shot I do not use autofocus! Instead I try to set a
>hyper-focal distance, with an appropriate f stop. the problem is that
>many of the ewer lenses, don't have the hyper-focal distance on the
>barrel. In that case I apply "Kentucky windage."



I have set the camera with a 600mm (4/3) lens on a
tripod in a room that overlooks the coffee shop
over the road about 25 meters away. The denizens
there sit at tables on the footpath/sidewalk
sipping lattes. The tables are randomly situated.
The camera fires once every 15 minutes. The
F-stop is 8.0 on aperture mode.

At the end of the day I check the photos and
discover the focus point varies randomly and there
seems no reason for this. Sometimes it focuses
on a lamp post and other times on a chair back and
sometimes on a subject.

Curious

Mort 01-06-2013 10:55 PM

Re: Olympus E5: 11-point TTL Phase Difference Detection
 
DanP wrote:
> I only use the central focus point, half press and recompose the frame.
> That way I get to focus where I decide. If I want to focus over a wider range I close the aperture. No guessing involved.



That's the way to go.I have been doing that for many years, after
getting tired of blurred faces and a sharp wall way behind the faces.

Mort Linder

Wolfgang Weisselberg 01-10-2013 10:18 PM

Re: Olympus E5: 11-point TTL Phase Difference Detection
 
DanP <dan.petre@hotmail.com> wrote:
> On Friday, January 4, 2013 2:57:11 AM UTC, Peter Jason wrote:
>> When I photograph a group of people, say 12, how
>> does the "11 point focus" know where to focus?
>> Does it go for the movement or does it average the
>> lot? There's no explanation in the manual.


> You'd be very lucky to have all focus points covering your subject(s).
> Some will be sitting over the background.
> It has to be a clever algorithm trying to guess what you want to do.


Nope. In most cases "closest distance" works very well: few
people shoot through fences or bushes or leafes to capture
the subject. Those that do know how to tell the camera which
focus point/points/point groups to consider.

However, today face detection can be an even better solution
when a face can be found, as most people want the faces sharp.


> I only use the central focus point, half press and recompose the frame.


And the larger the recompose angle, the more the recompose moves
the focus behind where you want it to be. Doesn't matter a
lot with tele lenses (small recompose angle) or when you have
much DOF.


> That way I get to focus where I decide.


I love the capability of the 5D3 to memorize a different
focus point (or group) for both portrait and landscape ---
thus I can offset it so I don't need to recompose much when
I'm photographing similar situations in a row in both
orientations. Like people on a stage ...

It's quite easier than central focus point only ... which I
used to do for many years.


> I don't like to use tools smarter than me, make me look stupid and not knowing what I am doing.


You *could* learn more about the tool --- it's not THAT smart.
Or you could switch to manual focus and manual mode.

-Wolfgang


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