Push processing

[1][page needed] Push processing involves developing the film for more time, possibly in combination with a higher temperature, than the manufacturer's recommendations.

Push processing allows relatively insensitive films to be used under lighting conditions that would ordinarily be too low for adequate exposure at the required shutter speed and aperture combination.

This technique alters the visual characteristics of the film, such as higher contrast, increased grain and lower resolution.

[2] John Alcott won an Oscar "for his gorgeous use of natural lighting" in Stanley Kubrick's 1975 period film Barry Lyndon, set in the 18th century, where he succeeded in filming scenes lit only by candlelight through the use of special wide-aperture Carl Zeiss Planar 50mm f/0.7 lenses designed for the low-light shooting on NASA's moon landings, and then push-processing the film stock.

[3] Larry Smith, the cinematographer for Kubrick's 1999 film Eyes Wide Shut, used push-processing to increase the intensity of the color.

A photograph pushed by 2 stops, showing strong grain
A roll of Cinestill 135 color film showing checkboxes that can be used to remember the EI for push-processing (expressed in stops relative to the box speed of ISO 800/30°).