I have a Canon 6D. The "File Numbering" setting is set to "Continuous", and for the most part, it behaves that way. However, unlike my experience with previous Canon DSLRs (e.g. my Canon 30D), there's a gotcha: When I format a card, the numbering sequence continues, but in the 100CANON folder.

So, for example, I can do this:

  1. Shoot an image - It gets id 0004, within folder 100CANON. On the display, this is listed as 100-0004.
  2. Format card. (Low-level format is off, in case that matters.)
  3. Shoot another image. It gets id 100-0005. Continuing, as I would expect.
  4. From the File Numbering menu, select Manual Reset.
  5. Shoot an image. This now gets id 101-0001. It's in the 101CANON folder. As I would expect, after the Manual Reset (There's also Select Folder -> Create folder, though that only changes the folder number, and the image number remains contiguous. If I did this at this point, and selected the newly-created folder, I'd get 102-0002, not 102-0001, which a Manual Reset would give me.)
  6. Format card.
  7. Shoot again. I'm now at 100-0002. So, it continued the image sequence, but reset the folder.

What I would like to have happen, instead of what I get in step 7, is to continue with the same folder number, as well, and thus get image 101-0002. With the canon 30D, this was what I got... and I could expect to combine the folder number and the image number together (as is done on the display during in-camera playback) to get a unique number across the life of this camera - provided I don't roll over past folder 999CANON.

Is this a bug? Is this something I can change somehow, in a menu item I'm not seeing? Is there a good workaround - perhaps re-formatting the card on the computer after extraction, and creating folders as needed, instead of doing it in-camera? (Would that get me into trouble? Some indications in this question seem to indicate that in-camera formatting is preferred, though there's not a clear explanation of why.) What if I skip doing "format", and simply erase all the files (leaving folders intact), either from the computer, or with 'Erase all images on card'? Will either of those be problematic in some way?

Anyway, the latter seems to work... removing all images (either from the computer (leaving the folders - or at least the last one - in place), or from the camera), without formatting the card (in either place), seems to keep my numbering doing what I want it to. I suppose I'll adopt this workaround (also known as a change in behavior; I grew accustomed to following the advice to "always format"). However, if anyone knows of a way to get the folder numbering to not reset in this way (or Canon, if you're listening, and could add such an option, or revert to your past behavior), that would be great to hear about.

I got 10,000 images (or so) into my use of this camera before noticing this problem... I look forward to having future photos have unique IDs, even if I got some overlap between the first time I formatted after rolling to 101CANON, and my early use of the camera. My import scripts renumber things based on folder number (and camera serial number, thus giving me a globally-for-me unique ID, in theory), so I'll maybe go manually renumber the almost 2000 images I shot before figuring this out (and/or before finding a solution), and I'll switch to "Erase all" from here on, and/or set something up to format and then re-create the folders, if that really does seem necessary for some reason.

  • 1
    Who moved my cheese?
    – Michael C
    Dec 13, 2013 at 3:55
  • Heh... Am I just complaining about change, @MichaelClark? Perhaps so. Well, I've got my workaround, I guess, and I've changed my "My Menu" to reflect it. Still, this strikes me as a regression, and a misrepresentation of what "continuous" numbering ought to mean... 100-0001 100-0002 ... 100-9998 100-9999 101-0001 101-0002 ... 101-0305 [format card here] 100-0306 What? Where'd that 1 go? :-P
    – lindes
    Dec 13, 2013 at 7:45
  • I pulled out my 50D and checked it. The 'new' system of resetting the folder # to 100 every time the card is formatted in camera is at least that old (2008). Since there has not yet been enough of an outcry from users to induce Canon to revert back to the old system in over five years, I wouldn't hold my breath for that. My import naming convention ignores folder numbers and instead adds the date the image was taken (IMG_yymmddxxxx.cr2 or MGC_yymmddxxxx.cr2). Though I guess it is theoretically possible to take more than 9999 images with the same camera in the same calendar day...
    – Michael C
    Dec 13, 2013 at 17:02
  • Yeah, I guess I'm a "bad consumer" - I hadn't purchased a DSLR since the 30D. ;) Anyway, the big reason I care about it is that while I'm shooting, if the folder-number is part of things, I can give someone (at an event, say) a 7-digit ID number (written on the back of my business card, say), and they can ask me for that image later, and I'll know exactly which one it is. (I actually prepend a letter, which is tied to the serial number of the camera I use, and which I know... thus truly making it unique for me.) I.e.: I can figure out the exact unique ID from the back of the camera.
    – lindes
    Dec 15, 2013 at 20:16
  • Since I generally know what the date is when shooting (:-) I could do the same thing on the back of a card: 131215-0001. The only difference is it would be 10 instead of 7 digits. Hey, the phone company has made most of us start dialing the area code for local calls as well as long distance, so we now have to remember 10-digit phone #s instead of 7.
    – Michael C
    Dec 15, 2013 at 21:57

4 Answers 4


Sadly, this seems to no longer be possible.

Posting an answer with the workaround I'm going with, though, so I can "accept" something (because I don't quite want to go with the other answer that's been given yet - though it does present other viable workarounds that some could use, and I welcome other answers, if folks have them):

Instead of doing a "format" each time, do an "Erase all images on card". This will leave the folder names intact, and the camera will continue to increase the combination of folder number and image number monotonically (until folder number gets to 999, and image number to 9999; after that, it resets).

  • 1
    The biggest downside to this method is that formatting allows the memory controller on the card to discover bad sectors and remove them from available space. Most flash memory cards are made with slightly more memory than the rated card capacity. This allows for any bad sectors to be 'masked' before leaving the factory and some of the excess memory is used on place of the bad sectors. As the card ages and sectors start going bad, the controller will continue to swap out bad sectors for some of the excess memory on the card. Since a vast majority of the chips are made by a small core of...
    – Michael C
    Dec 15, 2013 at 22:05
  • 1
    ...suppliers, often the chips that are provided to the premium manufacturers (SanDisk, Lexar, Transcend, etc) are those which have the fewest masked sectors when leaving the factory and the chips provided to lower end manufacturers are the ones that had more defects that had to be masked.
    – Michael C
    Dec 15, 2013 at 22:07
  • 1
    It is just my opinion based on an educated guess, but I think you will eventually have a greater chance of flash memory card problems by never formatting them than by regularly formatting and then creating/naming folders on the computer instead of in the camera. The 'always format in-camera' mantra was created because no one wanted to have to teach consumers how to properly set up a card for use on a different machine than the one it will be used in.
    – Michael C
    Dec 15, 2013 at 22:13
  • 2
    You can just copy the folders on a PC, format the card (in camera as you wish), then paste the folders back. I believe this will achieve the same result while gaining the benefits of doing a card format. Dec 31, 2013 at 2:31
  • 2
    Thank you @MichaelClark - this is the first time I've seen someone explain the reasoning behind "always format the card". Much appreciated.
    – FreeMan
    Aug 3, 2016 at 19:51

I'm not sure it is possible to do exactly what you want formatting the card in camera without modifying the code in the camera's firmware, but here are two possible workarounds that might work for you.

1) To the best of my knowledge recent Canon DSLR bodies in the xD series starting with the 7D in 2009 allow the user to change the image name prefix. The 5DIII includes this feature, and I assume the 6D does as well. (After looking at the 6D Instruction Manual, it seems the 6D does not have this ability. The 7D, 5DIII, and 1D X do include the feature. We're leaving this in the answer for the benefit of owners of those cameras who might benefit from using it.)

The default form of an image file name is IMG_0001.cr2, but I have my 7D set to use my initials: MGC_xxxx.cr2. This prevents me from having duplicate file names from my other body, a 5DII that does not allow customization of the prefix. Allowable characters are A-Z, 0-9, and _ (except for the first character which can not be an _. This is because when you are working in the AdobeRGB color space instead of sRGB, the first digit will be replaced with an underscore _.) That leaves you 36 allowable characters for the first digit and 37 for the following three digits. This works out to a little over 1.8 million unique combinations. Each time you format your card in camera, advance the prefix by one character. Start with AAAA, then AAAB, AAAC, and so on. When you reach AAA9, then roll over to AABA, AABB, AABC, and so on. You will have to rewrite your import scripts to use the image file prefix rather than the folder number, but both are four characters long. The advantage is that the prefix has over 1.8M possible combinations vs. the 900 possible combinations between 100 and 999 inclusive. You will likely never exhaust 1.8M codes.

2) Instead of formatting in the camera, use your PC. As long as you use the correct file system (FAT32) and set up the needed folder structure after you format the card via the PC there should be no issues using the card. The reason almost everyone says to format in-camera is because that is the most user friendly way to guarantee the correct file system and folder structure.

Page 135 of your EOS 6D Instruction Manual explains how to create the needed folder structure and how to name folders. All folders with images must be created inside a folder named "DCIM". Basically each folder name must have 8 digits consisting of three numerical digits from 100 to 999 and five alphabetic (or _) digits. There can only be one folder that begins with any unique 3 digit number between 100 and 999, regardless of the five alphabetic characters that follow. You can have both a folder "100AAAAA" and "101AAAAA", but not both a folder "100AAAAA" and "100AAAAB".

One easy way to do this would be to erase all images on the card (which would leave the folder structure intact), copy the card's disc image to your computer, format the card in camera, then copy the disk image back onto the card.

  • Thanks for your thoughts, Michael. As for point 1, that looks interesting, yet the 6D seems not to have this feature for some reason. (Or at least I'm not seeing it in the manual, nor in the menus, though perhaps I missed it?) Also, that strikes me as a more cumbersome step than I was hoping to take to get a card ready to shoot again. I want the old behavior that "just worked".
    – lindes
    Dec 13, 2013 at 7:40
  • As for 2, that might work, though I don't believe the filesystem is FAT16 - that couldn't accommodate the 64GB card I have. I imagine it's FAT32, though I haven't checked. Anyway, I'd rather do things in-camera... See here (the reply after the quoted thread) for one reason why... I'd like to have the camera be the device to do all the writing, to the extent possible. (Now if I could only tell MacOS not to add .fseventsd and such...)
    – lindes
    Dec 13, 2013 at 7:41
  • Yes, it is FAT32. Thanks for catching that. As for writing to the card using the computer instead of the cameras, se the new edits to the answer.
    – Michael C
    Dec 13, 2013 at 15:46
  • ScottieC at the link in your comment is correct about 'quick formatting' in-camera and wear leveling. I'm not sure ScottieC at the link in your comment is totally correct about corruption stemming from writing to the card from the computer. As long as your computer is capable of using FAT32 without adding additional stuff to the file system created on the card.
    – Michael C
    Dec 13, 2013 at 15:57
  • 1
    The memory controller on board the card itself handles wear leveling.
    – Michael C
    Dec 15, 2013 at 21:59

The in camera file numbering has always be clunky. (On all the versions of Canon camera that I have used) I have always ignored those and do the renaming before I import to computer. I am using Aperture, but I assume all good photo management software has functionality to do this on import.

  • Unfortunately, I'm really looking for something in-camera... I already do some degree of renaming on import, but I do that to a name that corresponds to the number on the camera display while shooting, and that's what I'm trying to get to increase monotonically. I've found a workaround that seems to work for me, and I'm thinking this answer really doesn't give me much to help things... downvoting. :-/
    – lindes
    Dec 18, 2013 at 8:51

I know this is an old thread but I find no new info on the 6D file renaming issue and until I got a new 7DMkII it never was an issue. It's convenient having my files come out of the 7D marked 7DM2 001 instead of IMG 001 but it's never been that important because I always change the photo name anyway.

I'm sure you've all done this, but I've always created a file folder for each camera (5D, 50D, or 7D) and downloaded the camera photos into their respective folders. I highlight all the photos in the folder and then I can rename the photos under Properties using the camera designation...if I want to (like 5D) and the computer will give it new consecutive numbers starting with 1. I name it by the event such as NewYears16. This is also when I entered copyright info and such, until I got a camera that did it for me.

If I need to know what camera a particular photo came from, it's in the EXIF information. If I want to put different camera photos in the order they were taken, I sort them by date and time first and then rename them. I've done it for so long the only thing that slows me up is the RAM in the computer. But I really do like the in-camera naming in my 7DM2. It just doesn't stay named that once it leaves my camera.

  • Thanks for this, but it doesn't actually solve the question I asked. I'm trying to get a unique ID out of the camera itself, which also matches what the camera displays as I'm shooting (so that if, say, I make paper notes of an image number to give to someone, that can be an exact match to my files later). This means I need the camera to not reset the folder number. "Erase all" has been a viable workaround for me. Occasionally, I'll actually format a card, and then I just make sure to make new folders until I'm back where I started. Not my idea of fun, but it works.
    – lindes
    Aug 22, 2016 at 16:38

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