Just get a new DSLR for Christmas? Had a DLSR for a year or two? Either case, is your firmware up to date (don’t assume new means up to date)? Nikon as well as other manufactures update their camera firmware continually. That’s a very good thing! And the majority of the time, the firmware is updated with no fanfare, it just gets released. For example, the Keymission 360 had a firmware update just last week! You need to go to your camera, toggle down in the menu to Firmware, check the numbers and then check if there is an update. You can check Nikon firmware updates here. Firmware updates can contain minor to major upgrades so it is important to keep them up to date!
