I recently ran into a situation where my SD card for my DSLR is full. I had already taken a backup of my photos inside the card and from what I have learned after reading some of the guides online that first formatting will erase the files permanently. And secondly, format types are kind of different in a Mac, than on a Windows machine.

I have a 64 GB card and as per this guide, I have use the exFAT format. I haven't applied anything, as I want to be sure whether it is right or wrong as I can't afford to experiment with things.

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    \$\begingroup\$ This makes it look like you are keeping all your pictures in the camera. Bad idea. SD cards are not too reliable (and can be stolen with the camera). Plus working with a near-full card prevents it from using wear-leveling and makes it wear out faster. Consider SD cards as a medium to transfer pictures from your camera to your computer and nothing more. The normal state of an SD card is "empty". \$\endgroup\$
    – xenoid
    Mar 17, 2020 at 14:33
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    \$\begingroup\$ This question is about the differences between Mac and Windows file systems, not photography, per se. The differences don't matter when cards are formatted in camera. \$\endgroup\$
    – xiota
    Mar 17, 2020 at 17:57
  • \$\begingroup\$ @xiota - yeah, that was actually the idea. But I appreciate community engaging and helping me with best of their knowledge. I am overwhelmed already! \$\endgroup\$ Mar 17, 2020 at 19:38
  • \$\begingroup\$ On Windows it is a pain in the but right from the getgo, with Mac it is super easy & intuitive, but then with each subsequent update it becomes more and more difficult until eventually you want to scream and dig up steve jobs in order to ask WHY \$\endgroup\$
    – Alaska Man
    Mar 17, 2020 at 19:54
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    \$\begingroup\$ @AlaskaMan what's the pain with a simple right click > format? \$\endgroup\$
    – phuclv
    Mar 18, 2020 at 13:21

3 Answers 3


Why not save all the confusion and just format it in the camera?

Both Mac and Windows can read, write and format exFAT, but you need to make sure you are using MBR rather than GUID and the correct sector size that the camera prefers.

Rather than have to work all this out, especially if you're not even sure what they mean… just let the camera do it instead. The camera will also by default add some special folders it needs (DCIM and additional folders inside that) that neither Mac nor Windows will know to create.

If you format in the camera itself, neither Mac nor Windows will have any trouble with the card, and the camera will be very happy too.

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    \$\begingroup\$ Dittoes: I never insert a camera card into my computer without write-protecting it first. I don't want Windows or MacOS to add their index files, thumbnail caches, etc. I let my camera do all of the writing. \$\endgroup\$ Mar 17, 2020 at 12:13
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    \$\begingroup\$ I've never actually been all that bothered about what my Mac writes to the card. I also delete as I import, so the Mac is doing most of the work. It doesn't seem to upset the camera at all. I do, however, always format in the camera, just to save the above 'faffing about'. \$\endgroup\$
    – Tetsujin
    Mar 17, 2020 at 12:18
  • \$\begingroup\$ What if I want to move the files to my laptop. In this case don't you think I should be using my Mac to first move and then format? @SolomonSlow \$\endgroup\$ Mar 17, 2020 at 19:32
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    \$\begingroup\$ @LucijaBardot, I don't understand. Tetsujin's suggestion pertains to how you clear out the card after you have copied the files. The suggestion, with which I and others here agree, is to use the "format card" function of the same camera in which you plan to re-use the card. How you copy the files, and to where, is pretty much up to you. \$\endgroup\$ Mar 17, 2020 at 20:13
  • \$\begingroup\$ @Tetsujin I never delete as I import. A bad transfer due to an issue with the reader, cable, destination hard drive, etc. could corrupt images that you do not know are corrupt until later, after you've erased the card! (Sure there are recovery techniques if the card has not been overwritten, but why risk that hassle if you're going to format again in camera before reusing?) I always backup my transfer and verify that I have two good copies of the images from a card before I format that card. \$\endgroup\$
    – Michael C
    Mar 18, 2020 at 22:57

I can only strongly recommend not to format the SD card for use in the camera on a Mac or PC. A lot of write failures that I hear from in the Fuji and Sony context (including freezing of the camera itself) have been traced back to SD cards that were not formatted in camera.

Telling us, that you ran into a full SD card and are only now creating a backup of it, shows me that you use the card to actually keep the photos permanently on the card.

I can only plead you not to do that. SD card failures are quite common. Almost every photographer that I know, had a failure eventually. There is a reason after all, that especially wedding photographers always demand 2 card slots in their cameras, just to have a backup if the main card dies during a session.

See this research of SD cards failing by Tony Northrup: https://www.youtube.com/watch?v=qqo-MtNy2Ps

Best practice is to copy all files from the card to you hard-drive as soon as possible and then reformat in camera, making sure the card is good to go and in the exact format that your camera likes.

SD cards are cheap, but photos and the connected memories are precious.

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    \$\begingroup\$ SD cards fail all the time. You can increase the fail-rate with user-error, but the truth is they're really fragile. I used to get through literally thousands of them for work. However, assuming no operator error, then I see no concern with using the computer to write or delete from them. The single main reason to use the camera to format in the first place it it's really hard to get it wrong that way. I fully agree, though, don't use them for storage long-term & absolutely never as the only copy of any data. \$\endgroup\$
    – Tetsujin
    Mar 17, 2020 at 15:39
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    \$\begingroup\$ @Tetsujin so what I understand is to move the files on Mac, but format it using my camera? \$\endgroup\$ Mar 17, 2020 at 19:36
  • \$\begingroup\$ @LucijaBardot Exactly that. \$\endgroup\$ Mar 17, 2020 at 20:20
  • \$\begingroup\$ @LucijaBardot Move the file to your Mac, back them up somewhere else (external hard drives are a lot cheaper per MB than flash memory is), THEN format it in camera. \$\endgroup\$
    – Michael C
    Mar 18, 2020 at 23:00

As noted in another answer, all major operating systems (Mac, Windows, and all Linux distributtions) can read, write, and format XFAT -- but it's probably better if you don't format your old cards, whether from computer or in camera. Keep them instead, and buy a new one.

Your 64GB SD card will probably cost less than $20 if you don't get it from a camera store (if you do, it might be five times that figure). For that price, I'd consider it worthwhile to keep the original card, like keeping negatives in file pages in a cabinet. Sure, this gives up the "bad frames are free" paradigm of digital, but it means you can go back and look at what you didn't like on the frames you didn't originally decide to keep, and learn from your mistakes.

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    \$\begingroup\$ SD cards are more robust than single use. Buying a new SD card everytime is unneccessary, as is trying to deal with content on piles of cards. \$\endgroup\$ Mar 18, 2020 at 19:49

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