What is HDR?
HDR stands for High Dynamic Range. Dynamic range is the difference between the lightest light and darkest dark. Once your subject exceeds the camera’s dynamic range, the highlights tend to wash out to white, or the darks simply become big black blobs. It’s difficult to record a photo that captures both ends of this spectrum. This is what HDR is: a specific style of photo with an unusually high dynamic range that couldn’t otherwise be achieved in a single photograph. A person's eyes has a much wider dynamic range than most cameras shooting in JPEG can capture. To me, this is how I see a scene normally.
How it works:
At the most basic level, an HDR photo is really just two (or three, or more) photos taken at different exposure levels and then combined together with software to create a better picture. Ideally, the photographer takes a range of bracketed photos – that is, photos of the same subject taken with varying shutter speed/aperture combinations in order to produce a set of images with varying luminosity and depth of field. Then, with the help of advanced post-processing software, the photographer is able to blend the photos together and create a single image comprised of the most focused, well-lit, and colorful parts of the scene.
Using RAW files to create HDR photos
I shoot exclusively in the RAW file format. It captures a much wider range of data from my camera sensor and allows me the expanded dynamic range I need to create HDR photos.