Ultra wide angle lens

However this does not always pose a problem, as even the sun in a photograph takes up such a small amount of space that its presence can often have little negative impact on the overall composition.

When using an ultra wide-angle lens, the sky often constitutes a very large portion of the frame, and may need to be darkened for the image to appear balanced.

Note that a polarizing filter, which also darkens the sky, will often give uneven results when used on an ultra-wide angle lens.

For a long time it was thought that only symmetrical optical diagrams could ensure the geometrically precise transfer of light without distortion becoming apparent near the edge of images (as the viewing angle increases).

However, with modern technology and understanding of optics, ultra wide-angle lenses can these days eliminate distortion almost completely.

[2] Longer lenses magnify the subject more, apparently compressing distance and (when focused on the foreground) blurring the background because of their shallower depth of field.

Leitz Elmarit R19/2.8 ultra wide angle lens for Leica R cameras
Ihagee Exa camera with Carl Zeiss Jena Flektogon 1:4 20 mm super wide angle lens
Curvilinear (above) and rectilinear (below) image. Notice the barrel distortion typical for fisheye lenses in the curvilinear image. While this example has been rectilinear-corrected by software, high-quality wide-angle lenses are built with optical rectilinear correction.
Bearing 8/3.5 fisheye. A capture of an entire scene, including the sun is shown (180-degree circular fisheye). The underside of the seagull is illuminated by flash
How focal length affects perspective: 18 mm (ultra wide-angle), 34 mm (wide-angle), and 55 mm (normal lens) at identical field size achieved by different camera-subject distances. Notice that the shorter the focal length and the wider the angle of view, perspective distortion and size differences change.