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  #1  
Old 04-08-2007, 12:25 PM
Mr.Bolshoyhuy
 
Posts: n/a
Default infinity focus

infinity focus

whats the opinion here of it? I suppose those single-use 35mm cameras
have infinity focus
as there is no focusing mechanism.
Set to it, the camera doesnt focus, thereby using less battery power.
But is it worth it?
Are the pics focused and properly exposed?
I really do hate to pre-focus and hold the shutter button half-way and
wait for the subject
to be where I want it. Also, if using f/8, it takes longer to focus,
thus the moment is gone
by the time you take the pic.

Also, center vs. multipoint focusing. Most pics taken using center
focus are out of focus.
Whats it used for anyway? I see no point in MF in P&S cameras as
well. It time consuming
and tedious.

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  #2  
Old 04-08-2007, 12:26 PM
Kevin McMurtrie
 
Posts: n/a
Default Re: infinity focus

In article <1176001360.321735.91650@l77g2000hsb.googlegroups. com>,
"Mr.Bolshoyhuy" <bolshoyhuy@hotmail.com> wrote:

> infinity focus
>
> whats the opinion here of it? I suppose those single-use 35mm cameras
> have infinity focus
> as there is no focusing mechanism.
> Set to it, the camera doesnt focus, thereby using less battery power.
> But is it worth it?
> Are the pics focused and properly exposed?
> I really do hate to pre-focus and hold the shutter button half-way and
> wait for the subject
> to be where I want it. Also, if using f/8, it takes longer to focus,
> thus the moment is gone
> by the time you take the pic.


No-focus cameras have the focus set a moderate distance out. With a
tiny enough aperture and a low enough resolution, infinity is within the
depth of field.

A good DSLR camera with a bright lens will eliminate focus lag. Once
you have a fast DSLR you'll never go back to pokey point'n'shoots.

> Also, center vs. multipoint focusing. Most pics taken using center
> focus are out of focus.
> Whats it used for anyway? I see no point in MF in P&S cameras as
> well. It time consuming
> and tedious.


Center focusing is what I mostly use. I aim at what I want to be in
focus, half-press, compose, and shoot. Multi-point is no good if you're
opening the aperture to intentionally blur an ugly background.

I finally figured out why you'd want to meter from a single point
off-center - races. You can set a far edge focus point so you can get a
focus lock before you're tracking the racer.
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  #3  
Old 04-08-2007, 12:26 PM
Bucky
 
Posts: n/a
Default Re: infinity focus

On Apr 7, 8:02 pm, "Mr.Bolshoyhuy" <bolshoy...@hotmail.com> wrote:
> I really do hate to pre-focus and hold the shutter button half-way and
> wait for the subject
> to be where I want it. Also, if using f/8, it takes longer to focus,
> thus the moment is gone
> by the time you take the pic.


can't you just use set focus, aperture, and shutter in manual mode?

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  #4  
Old 04-08-2007, 12:26 PM
Neil Ellwood
 
Posts: n/a
Default Re: infinity focus

On Sun, 08 Apr 2007 00:08:33 -0700, Bucky wrote:

>
> can't you just use set focus, aperture, and shutter in manual mode?


He can't. He has to learn how to.
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  #5  
Old 04-08-2007, 03:45 PM
Andrew Koenig
 
Posts: n/a
Default Re: infinity focus

"Mr.Bolshoyhuy" <bolshoyhuy@hotmail.com> wrote in message
news:1176001360.321735.91650@l77g2000hsb.googlegro ups.com...

> infinity focus


> whats the opinion here of it?


It's particularly useful if you're photographing scenery through a window,
to ensure that the camera doesn't mistakenly try to focus on reflections in
the window.


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  #6  
Old 04-08-2007, 05:30 PM
Mr.Bolshoyhuy
 
Posts: n/a
Default Re: infinity focus

On Apr 8, 3:54 am, Neil Ellwood <cral.elllwo...@btopenworld.com>
wrote:
> On Sun, 08 Apr 2007 00:08:33 -0700, Bucky wrote:
>
> > can't you just use set focus, aperture, and shutter in manual mode?

>
> He can't. He has to learn how to.


funny. I was referring to P&S cameras.

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  #7  
Old 04-09-2007, 03:34 AM
Bill Funk
 
Posts: n/a
Default Re: infinity focus

On 8 Apr 2007 09:16:53 -0700, "Mr.Bolshoyhuy" <bolshoyhuy@hotmail.com>
wrote:

>On Apr 8, 3:54 am, Neil Ellwood <cral.elllwo...@btopenworld.com>
>wrote:
>> On Sun, 08 Apr 2007 00:08:33 -0700, Bucky wrote:
>>
>> > can't you just use set focus, aperture, and shutter in manual mode?

>>
>> He can't. He has to learn how to.

>
>funny. I was referring to P&S cameras.


Owning a P&S camera does not automatically limit the user to no
control.
But, to answer your question, these cameras aren't limited or set to
"infinity". The aperture and focus are set such that infinity is
included in the DOF. How close the focus will go to is up to the
designers.

--
THIS IS A SIG LINE; NOT TO BE TAKEN SERIOUSLY!
The White House gave John Kerry's
campaign nemesis Sam Fox, who funded
the Swift Boat Veterans, a recess
appointment to Belgium on Wednesday.
Nothing ever changes. John Kerry
insisted he was for the appointment
before he was against the appointment.
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  #8  
Old 04-09-2007, 03:21 PM
Allen
 
Posts: n/a
Default Re: infinity focus

Kevin McMurtrie wrote:
<snip>
>
> No-focus cameras have the focus set a moderate distance out. With a
> tiny enough aperture and a low enough resolution, infinity is within the
> depth of field.
>



Many years ago there was a term for the point at which a set focus would
yield an acceptable sharpness for an object at "infinity" and also
provide that same acceptable sharpness (circle of confusion) at the
nearest point, for any given focal-length/f-stop combination. I have
wracked my brain trying to remember that term, with no success; does
anyone recall it? It _might_ have been "Hyperfocal distance".
Allen
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  #9  
Old 04-09-2007, 03:45 PM
David J Taylor
 
Posts: n/a
Default Re: infinity focus

Allen wrote:
[]
> Many years ago there was a term for the point at which a set focus
> would yield an acceptable sharpness for an object at "infinity" and
> also provide that same acceptable sharpness (circle of confusion) at
> the nearest point, for any given focal-length/f-stop combination. I
> have wracked my brain trying to remember that term, with no success;
> does anyone recall it? It _might_ have been "Hyperfocal distance".
> Allen


Correct.

http://en.wikipedia.org/wiki/Hyperfocal_distance

They give an example of focussing a 50mm lens working at f/16 to 5.2m,
when everything from 2.6m to infinity is then "in focus".

David


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  #10  
Old 04-09-2007, 05:13 PM
ASAAR
 
Posts: n/a
Default Re: infinity focus

On Mon, 09 Apr 2007 14:33:04 GMT, David J Taylor wrote:

>> Many years ago there was a term for the point at which a set focus
>> would yield an acceptable sharpness for an object at "infinity" and
>> also provide that same acceptable sharpness (circle of confusion) at
>> the nearest point, for any given focal-length/f-stop combination. I
>> have wracked my brain trying to remember that term, with no success;
>> does anyone recall it? It _might_ have been "Hyperfocal distance".
>> Allen

>
> Correct.
>
> http://en.wikipedia.org/wiki/Hyperfocal_distance
>
> They give an example of focussing a 50mm lens working at f/16 to 5.2m,
> when everything from 2.6m to infinity is then "in focus".


That's probably a useful definition for 4"x6" snapshooters, but
maybe not so good for others that occasionally make larger prints.
Maybe a better way to put it with that example would be that for a
specific print size, focus would be best at 5.2m, but at infinity
and 2.6m, sharpness would still be pretty good, but noticeably
inferior with closer than normal examination, or not very sharp in
larger size prints. For larger print sizes where a "smaller circle
of confusion" would be needed, the hyperfocal distance would move
slightly closer to infinity from 5.2m, and the DOF would also
decrease slightly with the "near" DOF border moving slightly closer
to infinity from 2.6m (by 1/2 the change in the h.d.) and the "far"
border remaining at infinity. And of course if you give pictures to
one of our professed pixel peepers whose places his proboscis
against the prints for perusal, all bets are off.


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