How to Create Custom Image Folders with a Nikon D3100
By default, your Nikon D3100 initially stores all your images in one folder, which it names 100D3100. Folders have a storage limit of 999 images; when you exceed that number, the camera creates a new folder, assigning a name that indicates the folder number.
If you choose, however, you can create your own, custom-named folders:
Display the Setup menu and highlight Storage Folder.
Highlight New and press the Multi Selector right.
You see a keyboard-style screen similar to the one used to create image comments.
Enter a folder name up to five characters long.
Use these techniques:
To enter a letter, highlight it by using the Multi Selector. Then press OK.
To move the text cursor, rotate the Command dial in the direction you want to move the cursor.
To delete a letter, place the cursor under it and press the Delete button.
After creating your folder name, press the Zoom In button to complete the process and return to the Setup menu.
The folder you just created is automatically selected as the active folder.
If you take advantage of this option, remember to specify where you want your pictures stored each time you shoot: Select Storage Folder from the Setup menu and press. Highlight Select Folder and press the Multi Selector right to display a list of all your folders. Highlight the folder that you want to use and press OK. Your choice also affects which images you can view in playback mode.
If necessary, you can rename a custom folder by using the Rename option on the Storage Folder screen. The Delete option on the same screen enables you to get rid of all empty folders on the memory card.