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Old Jun 28, 2005, 2:04 PM   #1
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back in the old days of 35mm SLRs, lenses hadmarkings to denote theapproximate distance at which the lens was focused. i know the FZ'z don't have that, and there's all sorts of stuff online about DOF and hyperfocal distances and the like, but my question is this: lenses used to be considered focusedat infinity when focused onanything beyond a certain distance. usually this was something between 30 and 100 feet, depending on the lens. manual focus lenses were limited in travel, and when you cranked the focus ring all the way around to the stop, you were at infinity. the FZ's electronic "manual" focus ring has no stops, so there's no way to tell if you've maxed out the focal distance, much less how far away that is.is there any way to find out how far away an object must be before it's considered 'infinity' for optical/focusing purposes with the FZ20?
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Old Jun 29, 2005, 12:59 PM   #2
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anyone got any ideas on this?
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Old Jun 29, 2005, 1:44 PM   #3
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Beyond a certain point everything is in focus. That depends on the amount of zoom used. Beyond the minimum focusing distance I'd say, though the camera needs to know the distance to the subject. If that distance is greater than a certain value focus is said to be at infinity.
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Old Jun 29, 2005, 1:51 PM   #4
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squirl033,

I'm not sure what, exactly, you're asking for. But that's me. :?

If it helps at all, I can point you to a few threads that pre-date your joining this group.

The first discusses a method of focusing to infinity with an FZ10. (This method may have been superseded with the "Landscape" scene mode, but I've not used that yet.) The discussion can be viewed at

http://forums.dpreview.com/forums/re...ssage=10885279

The second presents a label that Klaas Bloem designed for his FZ10 and a technique for using the manual focus ring to select 3M distance at various zoom ratios. (Klaas, where are you? We miss you.) The following link directs you to the discussion at

http://forums.dpreview.com/forums/re...ssage=10870039

and

http://www.users.bigpond.com/vkelim/...distance-scale

The link to his label doesn't appear to work any longer but you can see it at

http://klaas-bloem.fotopic.net/p7161591.html

Hope this helps.


Dick

[Edit: While these links refer to the FZ10, they should apply (with minor modifications if any) to the FZ15 and FZ20 as well.]


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Old Jun 29, 2005, 2:19 PM   #5
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PvB wrote:
Quote:
Beyond a certain point everything is in focus. That depends on the amount of zoom used. Beyond the minimum focusing distance I'd say, though the camera needs to know the distance to the subject. If that distance is greater than a certain value focus is said to be at infinity.
yeah... it's where that "certain point"is onthe FZ that's puzzling me...


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Old Jun 29, 2005, 6:23 PM   #6
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Acording to the online depth of field calculator at http://www.dofmaster.com/dofjs.html in the worst case (maximum optical zoom, maximum aperture), the FZ20's hyperfocal distance is 1202.9 feet.

I think hyperfocal distance is probably the answer to the question "where does infinity begin?"

At widest zoom, still at f/2.8, the hyperfocal distance is 8.34 feet!

It might be a good idea to verify these figures through some other source, before accepting them as gospel.
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Old Jun 29, 2005, 7:11 PM   #7
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"where's infinity?"

Sounds like a topic on a philosophy forum, not a panasonic forum :P :G
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Old Jun 29, 2005, 7:13 PM   #8
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trooplewis wrote:
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"where's infinity?"

Sounds like a topic on a philosophy forum, not a panasonic forum :P :G
there's one in every crowd! :G




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Old Jun 30, 2005, 12:04 AM   #9
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Oh yeah, and Buzz Lightyear wants to know how to focus on infinity...and beyond!:blah:
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Old Jun 30, 2005, 2:24 AM   #10
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I have talked with engineering at Panasonic on occasion, and they have assured me that sharp focus at maximum zoom is infinty on these cameras.

Theoretically, 1X(6mm) is 6.56 feet at max. focus, 2x is double that (13.12 feet at 12mm), 11X= 72.16 feet at 66mm, 12x=78.72 feet at 72mm.

Now that means that the zoom range from 11x max focus to 12x max focus is roughly 6.56 feet. Divide that by 6mm for the same range, and you get 1.09333333 feet per mm between 11 and 12 times. So the farthest point of focus is from 77.63 feet at 71mm to 78.72 feet at 12mm. Now, from what I have read in books on photography, typical dof is 1/3 in front of, and 2/3 behind the point of focus before you start messing with the aperture. (Keep in mind, that my numbers on dof may not totally hold up due to the natural magnification that comes with using small chips and lenses matched to them) o .364 feet in front of, and .729 feet behind the focus point. Which to my mind would make 79.45 feet the beginning of infinity.

Now, who wants to back me up? Shoot my math down? or Just accuse me of being on drugz for putting this much time into thinking about and posting this?

FZFUN/MainFragger/Ex-Stan
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