Stopping down

In photography, stopping down refers to increasing the numerical f-stop number (for example, going from f/2 to f/4), which decreases the size (diameter) of the aperture of a lens, resulting in reducing the amount of light entering the iris of a lens.^[1]^[2]^:112

Reducing the aperture size increases the depth of field of the image. In the case of film cameras, this allows less light to reach the film plane – to achieve the same exposure after stopping down, it is necessary to compensate for the reduced light by either increasing the exposure time, or using a photographic film with a higher speed. In the case of digital cameras, stopping down the aperture allows less light to reach the image sensor – to achieve the same exposure, it is necessary to compensate for the reduced light by either increasing the exposure time, or increasing the signal gain of the sensor by increasing the camera's ISO setting. Alternatively, more light can be added to the scene by increasing the amount of light illuminating the scene, such as by using or increasing the strength of electronic flash or other light sources.^[3]

As a lens is stopped down from its maximum (widest) aperture, most lens aberrations (spherical aberration, coma and astigmatism) are decreased, but lens diffraction increases. The effect is that for most lenses, the balance between the decreasing aberrations and the increasing diffraction effects of stopping down the lens means that lenses have an optimum aperture for best results, often about three stops closed down from maximum aperture, so for a lens with a maximum aperture of ƒ/2.8, ƒ/8 would be the optimum aperture.^[2]^:180

Photography

Outline

Terminology	35 mm equivalent focal length Angle of view Aperture Black and white Chromatic aberration Circle of confusion Color balance Color temperature Depth of field Depth of focus Exposure Exposure compensation Exposure value F-number Film format Film speed Focal length Guide number Hyperfocal distance Metering mode Perspective distortion Photograph Photographic printing Photographic processes Reciprocity Red-eye effect Science of photography Shutter speed Sync Zone System

Genres	Abstract Aerial Architectural Conceptual Conservation Cloudscape Documentary Ethnographic Erotic Fashion Fine-art Fire Forensic Glamour High-speed Landscape Lomography Nature Nude Photojournalism Pornography Portrait Post-mortem Selfie Social documentary Sports Still life Stock Street Vernacular Underwater Wedding Wildlife

Techniques	Afocal Bokeh Brenizer Contre-jour Cyanotype ETTR Fill flash Fireworks Harris shutter HDRI High-speed Holography Infrared Kirlian Kite aerial Long-exposure Macro Mordançage Multiple exposure Night Panning Panoramic Photogram Print toning Redscale Rephotography Rollout Scanography Sabatier effect Stereoscopy Stopping down Strip Slit-scan Sun printing Tilt–shift Miniature faking Time-lapse Ultraviolet Vignetting Xerography

Composition	Diagonal method Framing Headroom Lead room Rule of thirds Simplicity

Equipment	Camera light-field field pinhole press rangefinder SLR still TLR toy view Darkroom enlarger safelight Film base format holder stock Filter Flash beauty dish cucoloris gobo hood hot shoe monolight Reflector snoot Softbox Lens Wide-angle lens Zoom lens Telephoto lens Manufacturers Monopod Movie projector Slide projector Tripod head Zone plate

History	Timeline of photography technology Analog photography Autochrome Lumière Box camera Calotype Camera obscura Daguerreotype Dufaycolor Heliography Painted photography backdrops Photography and the law Glass plate Visual arts

Digital photography	Digital camera D-SLR comparison MILC camera back Digiscoping Digital versus film photography Film scanner Image sensor CMOS APS CCD Three-CCD camera Foveon X3 sensor Image sharing Pixel

Color photography	Color Print film Reversal film Color management color space primary color CMYK color model RGB color model

Photographic processing	Bleach bypass C-41 process Cross processing Developer Digital image processing Dye coupler E-6 process Fixer Gelatin silver process Gum printing K-14 process Print permanence Push processing Stop bath

Lists	Most expensive photographs Photographers Norwegian Polish street women

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References

↑ London, Barbara; Upton, John; Stone, Jim (2013). Photography. (Eleventh ed.). Pearson Education Canada. ISBN 978-0205933808.
1 2 Allen, Elizabeth (2011). The Manual of Photography. (10th ed.). Oxford: Elsevier/Focal Press. ISBN 978-0240520377.
↑ Langford, Michael; Bilissi, Efthimia (2010). Langford's Advanced Photography. (8th ed.). Oxford: Focal. ISBN 978-0240521916.

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