The human eye sees about the same field of view as a 50mm lens on a full frame digital camera (roughly 46 degrees). Of course we can actually see more widely than this but 50mm is generally accepted to be what we 'see', without getting into a snoreworthy discussion about peripheral vision and the like. This makes a 50mm lens the best choice for taking shots that look 'normal' to us, having a correct perspective and minimal distortion. This is especially important for keeping straight lines in architectural photography and flattering angles in portraiture, as lenses wider than this begin to distort the image as they capture a wider field of view.
Sometimes however a 50mm lens, or even a wide angle lens, simply won't do if you want to get all your subject or surroundings in one shot or convey the totally gobsmacking majesty of somewhere in the world you just spent a squillion bucks to get to.
|Anza Borrego Desert, July 2012, stitch of 9 images over 360 degrees|
|The road to Mauna Kea, Big Island Hawaii, 25 images, 360 degrees|
At this point I will welcome you to the wonderful world of panoramic images; by this I mean taking a series of single images of a scene and merging them into one shot.
|Dawn of the Supermoon May 2012, 8 images, 180 degrees, hand stitched|
Apparently some mobile phones and compact cameras now have auto-panorama features. I've seen people press a button on their camera or phone then spin around and out pops an acceptable panorama (unless you want to print it large I suspect and you're happy with whatever random settings the phone picks). It used to be that to make a nice panoramic photo you had to set your camera exposure and focal length manually and take a series of images, overlapping each a little, then open them all together and stitch the sons of beaches together in Photoshop.
|Brisbane, May 2014, 9 images around 230 degrees|
|Halemaumau Crater, November 2013, 11 images, over 180 degrees|
|Secret Island on Oahu, October 2013, 15 images, 180 degrees|
A good pano could take days of work. This is still the way I do it; taking a series of overlapping shots on a 35-50mm lens panning across my scene. Photoshop now has an automerge feature that does a pretty darn good job of making a single image out of a series. Unless you have moving lines in the image like surf, then it sucks at it; it's back to coffee, lots of squinting and doing the work yourself.
|End of Chain of Craters Road, November 2013, 34 images, 360 degrees|
Panoramas created like this of course make gigantic files that you can print pretty much the size of your street if you want. We have several done in this way in our own home to remember our travels.
|Oahu's west coast, October 2013, 13 images, close to 180 degrees|
|Go Padres! Petco Park in San Diego July 2012, 5 images, close to 180 degrees|