Nikon has added an in-camera HDR feature for the first time in their DSLR bodies with the D5100. The camera will take two photos with varying exposures; you can let the camera choose the exposure delta automatically or you can specify it yourself within a range of 1-3 EV full stops. You can also choose to let the camera automatically meter the scene for the base exposure or set the exposure manually in M mode.
Before I discuss the IQ there are a few quirks to the feature. First, the HDR option in the Shooting Menu is grayed-out if your image quality setting is RAW or RAW+JPEG; you must first choose a JPEG-only quality setting before the HDR option is available (btw, a big pet peeve of mine with the D5100 is that the camera displays a generic “This option is not available at current settings or in the camera’s current state” whenever you try to do something that is invalid for the camera’s configuration, rather than telling you what corrective action needs to be taken to make the option available). Another quirk is that the camera returns to non-HDR mode after you take a photo, so if you want to take multiple HDRs you have to return back to the shooting menu between each photo, or configure the Fn button to do this for you.
Quirks aside, how is the IQ for the HDR mode? Pretty good actually. I’m still evaluating exactly what tone mapping decisions the camera is making for different scenes but on balance the camera renders HDR how most shooters expect it should. Here’s a sample taken via a tripod. I haven’t evaluated the camera’s ability to align photos yet. I first took two raws with +0 and +3 EV, to demonstrate what the exposure is like, then took an HDR JPEG with the same exposure settings.