Olympus-OM
[Top] [All Lists]

Re: [OM] odd CF card (or E3) behaviour

Subject: Re: [OM] odd CF card (or E3) behaviour
From: "siddiq@xxxxxxx" <siddiq@xxxxxxx>
Date: Sat, 3 Jul 2010 00:07:58 -0700
On Jul 2, 2010, at 5:49 PM, Chuck Norcutt wrote:

> Ok, I'll try to make as much sense of this as I can.
> 
> In case 1 the scenario that makes most sense is that the card reader has 
> a problem.  I would normally say that the files on the card were 
> corrupted except you say you could view them on the camera.  If so then 
> the images on the card had to be good.  Since we won't hypothesize that 
> all 3 computers were bad the only common thing between them all is the 
> same card reader.  But there is still a possible fly in the ointment 
> here.  When you say you could view them on the computer

do you mean camera?

> do you mean as 
> in successively reviewing images in playback mode or was it just seeing 
> them pop up on the screen as they were shot.  If the latter you could 
> have been viewing just an image in the buffer that had not yet been 
> written to the card.  If that were the case the card could still have 
> been corrupt and you wouldn't have known it.  That would put the error 
> back on a corrupt card.

If above was supposed to be camera, i could view them successively, even 
magnifying some shots in playback mode to check expressions. Don’t have camera 
set to review image after exposure.


> 
> Case 2 is a total mystery to me except for hypothesizing an error in 
> finder since another app, iphoto, is able to display an entire image and 
> also export it intact.  That says the image on the card had to be there 
> in its entirety and was successfully copied to the computer.
> 
> But surely there is also a case 3?  You say you lost *all* of your dance 
> images even though you could recover older images with recovery 
> software.  Losing all of your just shot images is consistent with having 
> lost the directory.  That could happen if the camera was writing and 
> lost power or if the card was removed before the writing was done.  The 
> last thing that's written is the directory update to say where all the 
> files are located.  But that *shouldn't* happen with a normal power off. 
>  The camera is supposed to ignore power off until its done writing.  Of 
> course, if you pulled the card out of its slot before writing was done 
> the camera has lost control and you've lost your images.

That’s what I thought too, but I powered off the camera, walked back to office, 
and put card into reader. Plenty of time :( Lots of juice in battery. Wasn’t 
shooting in AFS or continuous-high-release mode either. 

> 
> Now then, why did the recovery software find old images.  It's because 
> there was still an old copy of the directory there and you deleted 
> images rather than reformat.  Deleting or erasing images doesn't 
> eliminate the directory entry that points to that image.  It only marks 
> the entry as deleted without actually erasing anything.  The original 
> entry is still there.  The camera's file system knows enough to ignore 
> the entry because it's marked as deleted.  But the recovery software 
> says, "Oh, Siddiq wants me to recover all this old stuff that's marked 
> deleted."  And that's what you got.  Your original images are probably 
> still there too but, because there was a valid but obsolete directory 
> there, that's what the recovery software picked up on.
> 
> More advanced recovery software could probably get them back but it 
> needs to know enough to scan the files themselves rather than the 
> obsolete directory.  If you had formatted the card rather than erased 
> files the recovery software would probably have picked up both the new 
> and old images but wouldn't know their camera assigned file names.
> 
> But I still can't explain everything to my complete satisfaction.  I'm 
> still bothered by the abberant behavior of the finder.
> 
> Chuck Norcutt

After the first occurrence, thought it was some freak accident, but now that’s 
it’s happened again, I’m wondering if I should worry :(

> 
> 
> 
> siddiq@xxxxxxx wrote:
>> On Jul 2, 2010, at 3:39 PM, Chuck Norcutt wrote:
>> 
>>> I'm having trouble here since parts of the story (as I understand
>>> it) don't seem to add up.  The clarifications you've added on this
>>> message and the previous one say the problem exists with the images
>>> as they are stored on the card because the corrupted images move
>>> wherever the card goes.  Or is it maybe the reader?  Does the
>>> reader move with the card? If that's true it's the camera, the card
>>> or the reader... it can't be the computer.  However you have also
>>> stated that, after a download, images on the same computer
>>> displayed by one application are corrupted but on another
>>> application they are not.  That says one of the apps is corrupting
>>> an otherwise fine image.  It can't be both ways... or if it is you
>>> have a truly confused problem scenario.
>> 
>> Sorries, was posting about two diff times this happened. The first
>> time (last month or so), all the pics on card, in camera, looked ok.
>> Put card in cardreader, Mac saw partial images (most were less than
>> 1/4th). Same card/reader on another  mac, and finally a PC, same
>> results, partial images.
>> 
>> 2nd time (yesterday), images reviewed on camera fine, but on mac
>> showed as partials in finder, complete in iphoto. if i exported them
>> out of iphoto (after importing them), they showed up complete images.
>> 
>> 
>>> You haven't used any recovery software on this card have you?  The
>>> scenario you describe (some JPEG images are truncated) can happen
>>> if you delete images on the card while you're shooting and the
>>> directory is later lost due to reformatting or other problems.
>>> With the directory gone or damaged the recovery software may not be
>>> able to figure out where some images start and end because (due to
>>> the intermediate file deletions) the image storage may not be in
>>> contiguous clusters.  Trying to read these back may produce only
>>> the first part of an image leaving some amount of the bottom
>>> portion chopped off.  The rest of the image is probably still there
>>> but the software can't figure out which intial image fragment it
>>> belongs to.
>> 
>> The only time I ran recovery app was when I lost the entire dance
>> shoot. Couldn’t recover any dance images (oddly, could recover photos
>> from prior shoots). I rarely delete images on camera, and never via
>> Explorer/Finder. Standard procedure is to first copy or import all
>> the photos to computer, put card back in E3, and delete all (or more
>> recently, format card, just because). I wonder if turning off the
>> camera right after a burst of images had anything to do with it? It
>> was just a power off via rear switch, not a battery-dying power off.
>> 
>>> Chuck Norcutt
>>> 
>>> 
>>> siddiq@xxxxxxx wrote:
>>>> On Jul 2, 2010, at 2:09 PM, Chuck Norcutt wrote:
>>>> 
>>>>> Now I'm totally confused.  The first part says the images were
>>>>> transferred to the computer OK but something unusual happened
>>>>> to them after they got there.  The second part says the problem
>>>>> moved to a different computer along with the card and reader.
>>>>> Got a different card or reader?
>>>> The first time this happend (last month I think), I did try
>>>> taking the card/reader to a PC and another Mac to eliminate my
>>>> own machine out of the loop. all three machines showed the same
>>>> partial image. Mac 10.5, 10.6 and WinXP/sp3
>>>>> Also I don't know what it means (physically) to "re-export" an 
>>>>> image from the iphoto library on a Mac.  I don't know if that
>>>>> means the image was physically copied to a different place or
>>>>> only that a pointer to it was handed off.  There are different
>>>>> implications of each.
>>>> importing copies to the applications photo library/database, so 
>>>> diff/new file, not a pointer to the same one
>>>> 
>>>>> Chuck Norcutt
>> 
> -- 
> _________________________________________________________________
> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
> Themed Olympus Photo Exhibition: http://www.tope.nl/
> 

-- 
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz