Anamorphic lens

Anamorphic lenses are a type of camera lens used to capture images. A non-standard device in television and often filmmaking also, they have very rarely been featured in the production of Doctor Who.

Anamorphic lenses are the key component of a process, initially intended for use with film stock, employed to produce a wider aspect ratio by way of recording a warped image which can be "de-squeezed" during projection (or post-production). In some cases, such as with the Dr. Who films' Techniscope, the anamorphic process is in fact limited to post-production, altering the dimensions of the image to conform to cinema standard formats.

Alternatively, the recording of footage with anamorphic lenses during principal photography, as during the Chris Chibnall era, entails the use of a different practice. The vertically extended frames, captured in the aspect ratio of the camera sensor, are reconformed to the geometrically correct aspect, in this case 2:1, thus restoring much of the expected geometry to the image. However, the opposite is also true: light features of the image that appear perspective-correct in the initial footage become distended as a result.

An example of the "blue streak" flares.

The visual makeup of the final product of anamorphic footage is thus qualitatively different to imagery captured by more standard spherical lenses. Many distinctive features caused by different attributes of the technology and process are observable. Shorter focal lengths exhibit increasing cylindrical curvature of geometry falling outside the centre of the lens, most visible in straight lines at horizontal extremes; squeeze/stretch factors, combined with shallow focus, produce vertically extended elliptical bokeh; the increased number of elements featured in the lenses leads to the preponderance of lens flares, including the unique long, horizontal blue "streaking", which in turn may be warped by image rectification. Technical differences further differentiate their profiles: shallower depth of field and reduced intake of light dictate much cinematographic decision making.

Lenses of this type used on the show include Cooke and Angenieux brand anamorphics.