I have a sizey problem and have never used forums but I have tried everything else so here goes!
Usual method of copying CR2 files:
Canon 5D mkiii
Legit Sandisk 16gb Extreme CF card
Copying the files to a late 2013 27" iMac.
The files seem to have corrupted somehow, I can only view about 30 images through the camera LCD, the rest come up with a question mark.
The CF card is identified by the mac BUT there are no files there, but within "get info" of the CF, it says it is a full card.
I have tried using different card readers.
I have tried copying the files to the SD card slot and putting them on the computer form the SD - the files are there and they are the correct normal file size but there is no preview and the file is un-openable in several programs.
I have tried formatting that SD card and using "card rescue" to bring them back but the same problem occurs.
I have contacted a specialist and he said he will try and get them back for $300 if recoverable and $0 if nothing is recoverable...
I am wondering if any legend out there can share some info to this rare case.... the photos are for a client and it's all quite stressful.
Clearly the data on your memory card is corrupted and it may be that the card, itself, is physically/electronically damaged.
If various photo-recovery programs cannot see the picture data then it card is probably bad and the images are lost. If only the directory information on the card is written incorrectly but the images are accessible on the card if you knew where the data was, then maybe an image recovery program that recognizes raw photos from your camera, would be able to find the other photos. Since you have now formatted your card, some of the directory information has been wiped out, so only a program that recognizes images would be of any use.
I'd suggest using as many photo recovery programs as you can, to see if any of them find more image thumbnails than the 30 or so you saw originally, and if so then try to recover using those. If no other recovery programs can find anymore thumbnails then the images probably are not there, anymore, because the card memory electronics are damaged. Usually the photo-recovery programs will scan and show you the htumbnails of images for free but then you have to pay to actually save off the recovered images. It could very well be that the programs are able to recover the embedded preview JPGs but not the raw data. The embedded preview JPGs are better than nothing.
Some higher-end cameras have two card slots and you can have the camera write the same image to each of two memory cards in case one of the cards goes bad. From what you say you must not have had your camera configured this way.