What is a Panorama?
Webster’s dictionary defines a panorama as “a full and wide view of something,” derived from two Greek words: pan, meaning “all,” and horama, meaning “sight, spectacle, that which is seen.” The first documented use of the word was in 1787 by Robert Barker to describe his paintings of Edinburgh and London. There is no formal aspect ratio or field of view (FOV) that defines a panorama, but it is generally accepted that to be a panorama a photo must have a field of view that is wider than the human eye and at least a 2:1 aspect ratio, meaning at least twice as wide as they are tall. Some people accept either characteristic to define a panorama, others insist on both characteristics being met. After much research, I’ve discovered there really is no concrete definition to what constitutes a panorama however.
Field of View (FOV)
Humans have an almost 180° horizontal field of view, but only about 120° of that is binocular (both eyes) with depth perception. Thus there is some disagreement on how wide a FOV a photo must cover to be considered a panorama. I personally go with around 140° or more horizontally. A full sphere would be 360° horizontal and 180° vertical. These spherical panoramas are my favorite type of panorama to shoot.
That brings up an interesting dilemma however—what of vertical panoramas?! Do they also need a 140° vertical FOV to be considered a “panorama”? Or would a vertical FOV of 70° or more be enough to qualify since that is about what a human can see with visual acuity without moving the eye? Perhaps the field of view is too difficult a measurement to define a panorama and the aspect ratio is a better requirement.
Most DSLRs (cropped sensor and full frame sensor) shoot an aspect ratio of 3:2 (or 1.5:1). Most point and shoot cameras, four thirds cameras, compact cameras, etc., have an aspect ratio of 4:3 (or 1.33:1). High definition video, such as DVDs, Blu-ray, HDTV, is typically 16:9 (or 1.78:1). Movies theaters are usually either 1.85:1 or 2.39:1, which gets into panoramic aspect ratio, but not usually the same FOV obviously (unless it’s an OmniMax theatre). Common print sizes for panoramas are 2:1, 2.5:1, 3:1, 4:1, and 6:1 so I tend to crop my panoramas along those aspect ratios for easier printing, my favorite being 3:1. Many places will do custom printing of any aspect ratio though. Some projections like stereographic or “little planet” and a hemisphere of the full sky are 1:1 or square and still considered to be a panorama due to the extreme field of view. From my research, the overwhelming opinion is that to be a panorama an image must be at least a 2:1 ratio minimum. The majority of photographers, print competitions, and panoramic associations didn’t stipulate the field of view as a requirement to be considered a panorama.
Wide-angle photography can often be confused as panoramic photography. A 14mm rectilinear lens like my favorite Nikon 14-24mm f/2.8 on a full frame 35mm sensor gives a horizontal FOV of 104°. You could crop the top and bottom off a single frame from that lens and call it a panorama, but a purist would still consider it to be wide-angle photography and not panoramic photography because the horizontal FOV is still less than human vision. A 16mm fisheye on the other hand has a horizontal FOV of 137° and a cropped 2:1 or wider aspect ratio could be considered a true panorama without stitching, although the subject would be distorted due to the projection.
Gigapixel and High-resolution Photography
The size or density of a photo has little to do with it being a panorama or not. A panorama does not have to be a very high resolution. Technically speaking, a gigapixel photograph is one that consists of more than 1 billion pixels, regardless of field of view or aspect ratio. A high-resolution stitched photograph in my opinion is one that is larger than your camera’s sensor by a significant amount. A high resolution or gigapixel image isn’t necessarily a panorama though since the aspect ratio might be less than 2:1 and the FOV might be less than human vision (regardless of aspect ratio), but most panoramic associations and print competitions do not seem to make this distinction. Ironically, many accept any high resolution or gigapixel stitched image as a panorama regardless of aspect ratio, which I find inconsistent. I tend to call anything higher than 50 megapixels, and not wider 2:1 aspect ratio, a high-resolution image and not a high-resolution panorama, but that’s my personal opinion. The same with gigapixel images.
In the photography world panoramas mean different things to different people, but generally it is accepted to be a bigger than normal view—whether that means aspect ratio, focal length, field of view, or size seems to be an individual interpretation. If this topic is of interest, I plan to write a series of articles on panoramas: their history, different types of projections and methods of displaying them, and also how to shoot and create them, covering both hardware and software from simple to complicated. Follow the New England Photography Guild blog or Facebook page for more!