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by Bruce Sherman on Fri Jun 30, 2017 9:09 pm
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Bruce Sherman
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I recently purchased a Sony a6000 for pics of family, grandchildren, vacations, etc. While on a recent trip I would download my pics each day (from a SanDisk 64 GB SD card) and then format the card in the camera. One day I accidentally deleted some pics before downloading and without realizing what I had done I formatted the card. I used the same card the next day and while downloading that day's pics I realized what I had done the day before. I did not format the card again.

When I returned home I tried to recover the missing pics from the card using SanDisk Rescue Pro Deluxe. The only pics that Rescue Pro would "recover" was pics from the last day. These pics had never been deleted. No pics from the second to last day or any prior days, i.e. pics that I had deleted, were recovered.

I have used Rescue Pro Deluxe in the past on a SanDisk CF card used in a Canon DSLR. I remember that there were pics from days and months earlier after the card had been formatted several times.

What's different this time that would not allow recovery of pictures taken before the last time the card was formatted? I never even came close to filling the 64 GB card at any time. Probably had a max of 4 or 5 GB.

Would appreciate any help. Thanks.
 

by aolander on Sat Jul 01, 2017 1:25 pm
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You can only recover files that weren't overwritten.
Alan Olander
Minnesota
 

by Royce Howland on Sat Jul 01, 2017 2:29 pm
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Yes, quite true. Files are stored on the card in a consistent order. If you format the card and shoot, then format the card again and shoot again, the 2nd batch of files overwrite the first. Generally you can't recover anything if the 2nd shoot had the same or greater volume of data written to the card. At best you could recover files from the 1st shoot that were not overwritten if the 2nd shoot had a lower frame count and didn't store as much volume of data on the card.

(Technically speaking this is a simplification. If the card's onboard controller is doing any kind of wear leveling then data will be written to different memory blocks to ensure that write operations are spread around the card. But as far as the camera or operating system is concerned, files are written in a consistent order. Any trickery happens at a lower level that isn't visible to the camera or computer.)
Royce Howland
Visit my web site for photo galleries, my blog and photo tours & workshops
 

by Bruce Sherman on Sat Jul 01, 2017 5:45 pm
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Thanks Royce and Alan. I think the total size of the pics I took on the last day was greater than I had taken on any other day with this camera so all previous files would have been overwritten. This would explain what happened.
 

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