Why do cameras put photos in multiple folders on a memory card?

Question

Recently when looking at my memory card I noticed that there were multiple folders on the memory card. The file path looked like this:

DCIM/100D5100
DCIM/101D5100 

The D5100 is the camera I am using but I have seen this behavior on multiple cameras. Why does the camera(s) automatically split the photos into multiple folders?

Note: The photos will go from 1 - 345 for folder 1 then 345 - 700 for folder 2 etc. but I have not seen any patterns that would dictate when a new folder is created.

Answer 1

This is really a case of read your camera manual. If your camera did not come with a full one, there will be one on a CD. The behavior greatly varies.

Usually cameras use filenames which gives them 4-digit numbering (some use 5 numbers), so you could in theory have 9999 photos in a single folder. However, cameras can break down these images in folders differently. Furthermore, some cameras let you control this using their Setup/Config menus:

• Some DSLRs like the Pentax K-5 aim to keep folders with a set number of images (500 in this case) but they can give you more since they won't break up a bracket.
• Some cameras wont break up bursts, some put them in separate folders.
• Some also have separate folders for images taken in panorama assist mode.
• A few models also break up folders by calendar days and name the folder according to the month and day.
• They can also break things by number of photos shot instead of counting the ones kept. In this case you will have always less than a certain number. Nikon entry-level cameras usually follows this approach with a limit of 499 or 999.
• Finally, some DSLRs, SLDs and a handful of ultra-zoom let folders be created by the user. In this case the folder still contains 3 digit sequence number which increments should the folder itself goes beyond the capacity which the camera likes.

Personally I find this annoying to have to copy from more than one folder but I'm not the one designing these things! What I do is to rename all files sequentially using a small Python script after copying the keepers to my computer.

Answer 2

On most (all?) cameras I have seen, the directories are numbered starting at 100, and the files are numbered 0000-9999 in each folder for up to 10,000 images in each folder.

One logical reason I can think of to split files like this is to avoid running into filesystem limits with the maximum number of files per directory. For FAT32, which most modern cameras use, there is a limit of 65,534 files per directory. By limiting to 10,000 images per directory, that means a maximum of (in most cases) 20,000 files per directory (if shooting in RAW+JPEG mode), which is well under the 65k limit.

Of course most memory cards will fill up with far fewer than 65k images (unless perhaps shooting with a very low quality).

The other reason I know of is simply for convenience sake. Numbering the directories and the files gives you an easy way to tell how many images you've taken.

Now, when you start swapping memory cards between cameras (or even in the same one) you often throw off the camera's internal counter, and it gets confused about where images should go.

Suppose you have two cards, one who's last image was stored as 101/5000, then you put in a new card which contains an image called 104/2000, the camera will (in my experience, although this is likely vendor/firmware specific) jump to 104/2001 for the next image. Then when you put the first card back in, the camera may not jump back to 101/5001, but may continue with 104/2002, thus leaving you with an apparent gap in your photo numbers.

Answer 3

Flimzy is on track with his theory about filesystem limits, but not quite. I don't recall it completely (it's been a couple of years since I learned it at the university) but the actual reason is performance. The more files you put in a directory the more difficult it gets to handle them. A list with 1000 files consumes much less memory than a list with 10.000 files, so this immensely speeds up filesystem operations, especially in a small system like digital cameras. Filesystem operations being: listing files, deleting files, creating previews (especially multiple images in a grid).

One could argue here that modern cameras should have enough computing power to handle such tasks, maybe this is correct. I have no idea what kind of processors are used in digital cameras, maybe this behavior is a relic from older cameras and the engineers program them out of habit that way.

Answer 4

On my Nikkon D5100 it puts 1000 photos in each directory. The problem, as mentioned above, is that when connecting to the PC from the camera, Windows Exploerer does not see the folders. I recently had over 2300 photos from one session. I only got the photos from the first one. I have a USB chip reader that supports a number of different chips. Using this, Explorer saw the three folders o the chip and I could copy them easily to my PC. This is easier than writing a script,

Answer 5

Consider this: 1000, 5000, or 10000 files (photos) per folder, you're always at risk of losing some if they get consolidated into any SAME PC folder.

Once you see the message "File IMG 3333 (OR, any # from 1 - 9999) already exists in the folder you are moving [or copying] to -- do you wish to proceed"?

Which image do you wish to lose? Neither, I'll bet. Retaining the 3-digit prefix # of the camera's folder, along with the 4 digit file # (yyy-xxxx) provides a unique "Serial #" for each & every photo. No matter which or how many ever are directed to a same PC folder, no 'either / or' response will ever cause the loss of one or the other.

Thank you, camera designers, for the foresight. But few users catch on right away, indicating you just need to communicate more thoroughly in you manuals.