How to Protect Photos on a Nikon D3100 or D5100
You can protect pictures from accidental erasure by giving them protected status on your Nikon D3100 or D5100. After you take this step, the camera doesn’t allow you to delete a picture from your memory card, whether you press the Delete button or use the Delete option on the Playback menu.
You can also use the Protect feature when you want to keep a handful of pictures on the card but delete the rest. Instead of selecting all the pictures you want to trash, protect the handful you want to preserve. Then set the Delete menu option to All and dump the rest. The protected pictures are left intact.
Formatting your memory card, however, does erase even protected pictures. In addition, when you protect a picture, it shows up as a read-only file when you transfer it to your computer. Files that have that read-only status can’t be altered until you unlock them in your photo software. In Nikon ViewNX 2, you can do this by clicking the image thumbnail and then choosing File→Protect Files→Unprotect.
Protecting a picture is easy:
Display or select the picture you want to protect.
*In single-image view, just display the photo.
*In 4/9/72 Thumbnail mode, use the Multi Selector as needed to place the yellow highlight box over the photo.
In Calendar view, highlight the image in the strip of thumbnails that appears on the right side of the screen. (Press the Zoom Out button to jump between the calendar dates and the thumbnails.)
Press the AE-L/AF-L button on your D3100 or D5100.
See the key symbol near the button? That’s your reminder that you use the button to lock a picture. The same symbol appears on protected photos during playback.
To remove protection with the camera, display or select the image and then press the AE-L/AF-L button again.