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Old Jul 5, 2018, 1:19 PM   #1
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Default focus at infinity

Hi,
I have a z712 which allows 4 choices wrt focusing. AF/Macro/Manual/ and Infinity. Here's how the manual describes them:

Working range:
Auto: 19.7 in. (50 cm)–infinity @ wide; 47.2 in. (120 cm)–infinity @ telephoto
Close-up/Macro: 4.7–23.7 in. (12–60cm) @ wide; 7.9–51.2 in. (60–130 cm) @ telephoto

If I read this right, it defines infinity as 50cm wide open, and 120cm at full telephoto. Macro and manual I get; but I'm not sure what the difference between AF and Infinity is; except perhaps that AF doesn't focus until you half depress the shutter button.
Does anyone have a better handle on this?
Thanks,
..... john
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Old Jul 5, 2018, 8:14 PM   #2
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Quote:
Originally Posted by Shinnen View Post
Hi,
I have a z712 which allows 4 choices wrt focusing. AF/Macro/Manual/ and Infinity. Here's how the manual describes them:

Working range:
Auto: 19.7 in. (50 cm)–infinity @ wide; 47.2 in. (120 cm)–infinity @ telephoto
Close-up/Macro: 4.7–23.7 in. (12–60cm) @ wide; 7.9–51.2 in. (60–130 cm) @ telephoto

If I read this right, it defines infinity as 50cm wide open, and 120cm at full telephoto. Macro and manual I get; but I'm not sure what the difference between AF and Infinity is; except perhaps that AF doesn't focus until you half depress the shutter button.
Does anyone have a better handle on this?
Thanks,
..... john
That sounds about right. My old Panasonic FZ28 would have a different minimum focus based the focal length depending on the mode used. It had a momentary display to indicate what the distance was.

I had a Kodak ZD710, but I can't remember how it did work. I know it didn't have that scale like the Panasonic.
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Old Jul 5, 2018, 9:34 PM   #3
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Infinity isn't a separate mode.

What the manual is telling you is that, in wide angle, the camera will focus between 50cm and all the way to infinity, whereas in telephoto, it will focus between 120cm to infinity. At the macro/close up setting, it will focus between 12 and 60cm in the wide angle mode, and between 60 and 130cm when in the telephoto mode. In close up mode, it won't focus all the way to infinity.
Taken from the Z612 review:
AF range:
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    Old Jul 5, 2018, 11:08 PM   #4
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    What strikes me odd though, is that 2 of the 4 options appear to serve the same function. One shows only [AF], and the other shows [AF] and a mountain icon. (The other two are Manual, and Macro/[AF])
    ..... john
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    Old Jul 6, 2018, 10:00 AM   #5
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    Apparently, the landscape mode ignores the program to focus on foreground objects, and just sets focus to infinity, which makes sense if you aren't using manual focus and want to be sure of having distant objects sharp.
    https://resources.kodak.com/support/..._UG_GLB_en.pdf
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    Old Jul 8, 2018, 6:27 PM   #6
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    Quote:
    Originally Posted by Shinnen View Post
    Hi,
    .... If I read this right, it defines infinity as 50cm wide open, and 120cm at full telephoto. .... Thanks, ..... john
    G'day John
    You're also talking about 'infinity' ...

    A couple of thousand years ago when I was studying optics as part of the Photography Diploma course at Melbourne's RMIT [now RMIT university], the recognised industry standard for infinity was "1000x the focal length of the lens". I understood this to be a recognised standard thru the optics industry and have never seen anything that might alter this

    Therefore - as the lens focal length alters, be it a series of prime lenses -or- a zoom lens, the "infinity distance" will alter accordingly

    Hope this helps
    Phil
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    Last edited by Ozzie_Traveller; Jul 8, 2018 at 6:31 PM.
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    Old Jul 9, 2018, 4:43 PM   #7
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    OK. Thank you all for your help.
    ... john
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