Canon EOS 90D Instruction Manual page 724

Formatting Memory Cards
Conditions Requiring Card Formatting
The card is new.

 The card was formatted by a diff erent camera or a computer.
The card is full of images or data.
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A card-related error is displayed ( = 613).
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Low-Level Formatting
Perform low-level formatting if the card's writing or reading speed seems

slow or if you want to totally erase the data on the card.
Since low-level formatting will format all recordable sectors on the card,

the formatting will take longer than normal formatting.
During low-level formatting, you can cancel formatting by selecting

[Cancel]. Even in this case, normal formatting will already be complete
and you can use the card as usual.
Card's File Formats
SD/SDHC cards will be formatted in FAT32. SDXC cards will be

formatted in exFAT.
When recording a movie with a card formatted in exFAT, the movie will be

recorded in a single fi le (instead of being split into multiple fi les) even if it
exceeds 4 GB. (The movie fi le will exceed 4 GB.)
It may not be possible to use SDXC cards formatted with this camera in other
o
cameras. Also note that exFAT-formatted cards may not be recognized by
some computer operating systems or card readers.
Formatting or erasing data on a card does not completely erase the data. Be
o
aware of this when selling or discarding the card. When disposing of cards,
take steps to protect personal information if necessary, as by physically
destroying cards.
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