OH oh 40D missing files - WTF?

[MathewLodge]

This really does sound like a CF card issue, based on what Chuck has stated.

What's puzzling is the fact that the images could be read at one point, and now can't be -- which suggests something flipped bits in the CF card between it being packed away and unpacked at your studio. This is possible, of course, through electrical damage (typically static electricity discharge).

If there are bad memory cells or flipped bits in the sectors on the CF card that the FAT32 file system used for storing the directory contents, then the content of the files themselves could be on the CF card (i.e. the sectors containing the contents would be written) but they would have no directory entries -- so recovery tools wouldn't be able to "see" them.

The potential here (and it is a long shot, to be sure) is to make a sector-by-sector copy of the CF card, and then search it with a hex editor for something that looks like the start of a Canon Jpeg file header. Then you'd pray that the 40D wrote the file to consecutive sectors and hope you could recover it all by pulling out everything up until the start of the next Jpeg header you spotted. Repeat until you pull out everything that looks like a Jpeg and review them all. That's the theory -- no idea how you'd actually do it with standard tools (not my specialty).

Mathew

[DougAxford]

Thanks for the reply. I doubt that there was any electrical problem. I don't pack CF cards, they stay in the camera until moments before being read by the reader.

The recovery software clearly shows no other artifacts except as noted earlier.

My question still remains: Is there any way to duplicate this and if it does happen again, then what. If there is a problem with the CF card, how can I prove this without having to send it to the mfg.?

Right now, I have set aside the camera and card and I won't be needing it soon - got others that I can rely on.

Doug

[imported_ChrisP]

What firmware are you running? Canon had some issues like this and they updated the firmware.
It only happened once to me but the 'missing' images were put into place where I had deleted files. FIlling in the blank spots, so to speak. Since then I NEVER delete files on the camera - too damned freaky.


I saw it happen too, luckily. I had just gotten the camera and was playing with HTP and chimping and took a shot and it reviewed on the LCD, then took another with HTP off or on, whatever, and it came up. I then hit the 'play' button so I could scroll between and compare them and they weren't there! At home later I found them stuck in the middle, numerically speaking.

Have you sorted all your files by shoot time to see if they show up? Even if the numbers are out of sequence the times will be right.

[Buddy Thomason]

A few thoughts...

If I understand correctly, there's little support for a camera related issue causing the lost images.

You say the card was used "hundreds of times before." I have gained the impression over time that these cards have a limited functional lifespan and should be replaced well before reaching that limit. What is the limit? Memory card makers don't say and in reality may not even know. Routine replacement of memory cards probably makes sense even in the absence of reliable lifespan data - as part of the cost of doing business. Having successfully used that card as much as you have, it would be difficult to argue a mfg defect or design flaw.

Do you sometimes delete non-keepers as you go? I've accidentally lost good images while hurriedly deleting rejects to avoid running out of space on the card. As card capacity has increased and because my 1D series bodies provide a second card slot my behavior has changed. I don't worry about exhausting available memory any longer, so I have quit trying to delete non-keepers on the fly.

I understand both of these possibilities may seem unlikely from your point of view but on the other hand, expert status not withstanding, the answer is probably somewhere among all the ideas mentioned in this thread.

[Buddy Thomason]

Originally Posted by DougAxford

My question still remains: Is there any way to duplicate this and if it does happen again, then what. If there is a problem with the CF card, how can I prove this without having to send it to the mfg.?

- I'm assuming there's no way to reliably or consistently duplicate the problem.

- If it happens again... Well, it happened once - with that card. I'd retire (destroy or recycle) that card and not use it again for anything.

- Unfortunately, proof of a CF card problem in this situation, if possible at all, might best be established by factory testing. If that's true then I'm confused as to why you wouldn't want to send them the card for examination. There's nothing to lose and you probably won't be using that card again anyway.