5D Mark IV unexpected creates new folder on CF card

[rusty007]

It used to be that a new folder on the CF card was created after a lot of images were taken, like a thousand, but now I'll shoot a bunch of frames in the 100 folder and the next day's shoot will start in a 102 folder. For example, after formatting the card the 100EOS5D folder fills after 40 frames then the next day a new folder is started. The first folder ended in frame 1X1A2605. The current card is a 128GB but I did swap it for a new 64GB to test it was working OK, then went back to the newly formatted 128. I can't work out what's happening and why the sudden change after years of working as expected. Its on continuous file numbering.

[p4pictures · Accepted solution]

The folder and file number depend on a combination of factors. 

You format a card so naturally it’s blank and folder 100EOS5D is created, but the file number carries on from the previous last file number. So if previously 1X1A2605 was the file the first one on the newly formatted card will 1X1A2606. 

However when you remove the card, if you have an SD card in the other slot, and you close the card door. The camera will now see the SD card and use the higher folder and image number from that card. So if the SD card has 101EO5D on it and image number 1X1A6000 then when you open the card door and put in the fresh formatted card the camera will create folder 102EOS5D so as not to flash with ans image on the SD card and also update the camera filename to 1X1A6001.

Each folder on a card will only hold images from 0001 to 9999, but once it reaches 9999 the next image will be 0001 in a new folder even if there was only that one image 9999. 

The key is that closing the card door with an SD card in will update the camera image file number and folder to avoid a clash of file names and folders.