Cameras · two Canon exFAT cards
Canon dual-slot backup is incomplete
Why is one Canon card missing files from a dual-slot shoot?
Short answer
Often by design, not deletion: in Canon's standard, auto switch or record separately modes, the two cards are meant to hold different files, and stills and movies can go to different slots. Only record to multiple mirrors both. Check the configured slot function, compare filename ranges on both cards, and scan only for genuine gaps.
The situation
One slot contains a shorter filename range than the other.
Before treating this as a loss, read which slot function the camera was set to. Only recording to multiple cards mirrors everything; standard mode, auto switch and record separately each fill the two cards differently, and stills and movies can be routed to different slots as well.
01 / Diagnose
Work out what actually disappeared
In standard mode the body writes to the selected card until it is full, auto switch then continues on the second card from that point, and record separately sends RAW to one card and JPEG to the other. Each of those leaves a filename range with legitimate gaps compared to the other slot. Only the record to multiple setting should produce two matching cards.
Backup, auto-switch, RAW/JPEG split, and still/video separation produce different expected contents.
Check the last known path, trash and backups without writing to the original device.
02 / Protect the source
Preserve the best recovery chance
- 1
Look up the slot function and the still and movie routing in the camera menu or in the settings stored with the images.
- 2
Take both cards out, label them by slot and list the filename ranges and capture times each one actually holds.
- 3
Mark the gaps that the configured mode does not explain and treat only those as candidates for a recovery attempt.
- 4
Scan just the card with the genuine gap, read-only, and export its results into a folder named after that slot.
Do not copy files between the two cards to make them match, and do not format the shorter card because it looks incomplete. A card that was never meant to hold those frames has nothing to give back, while the card that did still holds the evidence.
03 / Choose the method
Match the tool to the source
For stable, readable exFAT, NTFS and FAT16/FAT32 or uncompressed IMG, DD, RAW and BIN images.
Unconfirmed exports are marked .UNVERIFIED.
Where the configured mode never wrote a file to a card, no scan can produce it, and a full card in auto switch mode is not a fault at all. File Recovery Hero reads exFAT, NTFS and FAT volumes read-only and repairs neither damaged clips nor incomplete backups.
04 / Verify
Check the recovered content, not just its name
The shoot is complete when every frame number from the camera counter appears once on its intended slot, when files recovered from a card open at full resolution or play to the end, and when mirrored pairs from the record to multiple setting agree in size.
Keep the source until two verified copies exist. One working preview is not enough.
Sources and technical references
FAQ
Questions about this recovery case
Can two Canon exFAT cards be recovered in this situation?+
Before treating this as a loss, read which slot function the camera was set to. Only recording to multiple cards mirrors everything; standard mode, auto switch and record separately each fill the two cards differently, and stills and movies can be routed to different slots as well. The result still depends on what remains readable on the source.
What should I avoid before scanning?+
Do not copy files between the two cards to make them match, and do not format the shorter card because it looks incomplete.
Does scanning write to my memory card?+
Your memory card is only read. Nothing is saved to it.