AF 'beeping success', but completeley out of focus

kirschm

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I am just testing my 2 year old Panasonic 20/1.7, because sometimes the AF is out of focus.

Test environment:
Center (small) focus field, no eye detection, high contrast subject within the focus field, not very bright (inside room conditions), using tripod for constant results.

It might happen that I focus 30x and everything looks good (e.g. when checking by the magnification).

Then the next 30x (same unchanged condition) the AF also tells me 'success' (by this beeping noise), but the result is completely (not only slightly) out of focus.

What's the reason for 'indicating success', but beeing completely out of focus?
 

taz98spin

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I have a E-P5 and when I use my Oly 25/1.8 with it, I will always get the green confirm and beep noise indicating that the AF is in focus, but sometimes the shots are not in focus.

It seems to me the focusing system is overly eager to focus?
 

sammykhalifa

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I know I have more success with AF on my EPL 2 when I switch over to the small focus box. There are instructions on it somewhere but I can't seem to find it right now.
 

kirschm

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I know I have more success with AF on my EPL 2 when I switch over to the small focus box. There are instructions on it somewhere but I can't seem to find it right now.
Sorry, forgot to mention: I already use the small focus box...
 

dhazeghi

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Do you mind posting a full-sized example (on Dropbox etc.)? I do see occasional false confirmations on the E-PM2 with the 20/1.7 in lower light, but it is the exception, not the rule.
 

kirschm

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Do you mind posting a full-sized example (on Dropbox etc.)? I do see occasional false confirmations on the E-PM2 with the 20/1.7 in lower light, but it is the exception, not the rule.
It's not an issue of the PM2... I used the Pana 20/1.7 for more than 2 years with my old PL1 and PL2... I just checked all those pictures... and it's the same... be it PL1, PL2 or PM2...

E.g. focussing a 3 meter subject... completely out of focus... and the focus distance in exiftool.exe shows 'infinitiy' as distance... I know the exiftool info might not be reliable... but in my cases it always reflects the mal-focussing of the Pana...
 

kirschm

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I now decided for an alternative solution regarding Pana 20/1.7 and Olympus body (I have a separate Olympus body for the Pana only... I don't like changing lenses).

I use a 'fast big sensor compact camera' for low light shooting (e.g. my Samsung Ex1)... the results in practice are better than Oly body plus Pana 20/1.7... a much better 'IBIS' (even 1/8 sec no problem) and very reliable focussing...
 

dhazeghi

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It's not an issue of the PM2... I used the Pana 20/1.7 for more than 2 years with my old PL1 and PL2... I just checked all those pictures... and it's the same... be it PL1, PL2 or PM2...

E.g. focussing a 3 meter subject... completely out of focus... and the focus distance in exiftool.exe shows 'infinitiy' as distance... I know the exiftool info might not be reliable... but in my cases it always reflects the mal-focussing of the Pana...
Well, if it happens consistently and across different bodies, I'd be inclined to blame the problem on a bad copy of the lens. In theory this sort of thing shouldn't happen with CDAF, but I have seen reports of misfocussing lenses due to bad AF motors, though not of the 20/1.7 specifically.

One other thing to do is to clean the contacts on the lens with isopropyl alcohol and ensuring that it is well seated.
 

phigmov

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It would be good to see an example if you can post one.

Two quick things -

* Sometimes I notice I get an AF confirm even though I'm out of focus - this is often because I'm within the minimum focus distance (usually me shooting flowers with a 20 or 45) and shooting a burst with unsteady hands
* Sometime I get the thing I intended to be in focus, just out of focus (ie the AF has locked onto something else entirely and I'm blissfully unaware)

Does using a centre-focus or tap-to-focus make any difference or increase your odds of a keeper ?
 
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