Search results for “Aperture”

Aperture Exposure & Metering f-stops (EV) The adjustable opening inside a lens that controls how much light passes through to the sensor, and with it the depth of field. N = f / D

Aperture Blades Optics, Lenses & Filters count The overlapping leaves inside a lens that form the iris, whose number and shape determine the geometry of the opening.

Aperture Priority Exposure & Metering A semi-automatic mode, marked A or Av, in which the photographer sets aperture and ISO while the camera chooses shutter speed.

Effective Aperture Exposure & Metering f-stops (EV) The working f-number of a lens once it is focused close, which is always darker than the marked aperture because the lens is extended away from the sensor. N_eff = N × (1 + m)

Camera Obscura Film, Darkroom & Historic Processes A darkened room or box in which a small aperture projects an inverted image of the outside world onto an inner surface.

Depth of Field Preview Cameras, Formats & Systems A control that stops the lens down to the working aperture so the actual depth of field can be seen before exposure.

Depth of Field Scale Focus & Depth of Field m / ft Markings on a lens barrel showing the near and far limits of sharpness for each aperture at the set focus distance.

Diffraction Optics, Lenses & Filters µm The spreading of light waves as they pass the edge of an aperture, which softens the image at small f-numbers. d = 2.44 × λ × N

Diffraction Limit Optics, Lenses & Filters f-stops The aperture beyond which diffraction, rather than lens design or sensor resolution, becomes the factor limiting sharpness. N_limit ≈ pixel pitch / 1.22λ

Entrance Pupil Optics, Lenses & Filters mm The apparent size and position of the aperture as seen from in front of the lens, which is what the f-number is calculated from. D = f / N

Equivalent Exposure Exposure & Metering stops (EV) Any different combination of aperture, shutter speed and ISO that yields identical image brightness. N₁²/t₁ = N₂²/t₂

Exit Pupil Optics, Lenses & Filters mm The apparent size and position of the aperture as seen from behind the lens, which governs how light strikes the sensor.

Exposure Exposure & Metering lux-seconds (lx·s) The total amount of light that reaches the sensor or film, set by the combination of aperture, shutter speed and the scene's brightness. H = E × t

Exposure Triangle Exposure & Metering stops The teaching model that links aperture, shutter speed and ISO as three interdependent controls, where changing one requires compensating with another. Aperture ↔ Shutter ↔ ISO

Exposure Value (EV) Exposure & Metering EV A single number describing every combination of aperture and shutter speed that produces the same exposure. EV = log₂(N² / t)

F-number Exposure & Metering Dimensionless ratio The ratio of a lens's focal length to the diameter of its entrance pupil, written f/2.8, f/8 and so on, and the standard way of stating aperture. N = f / D

Guide Number Lighting & Flash m at ISO 100 A measure of a flash's power, equal to the product of the correct aperture and the subject distance at a stated ISO. GN = N × d

Low-light AF Rating Focus & Depth of Field EV The dimmest light level at which a camera's autofocus is specified to work, quoted in EV at a stated aperture and ISO.

Manual Mode Exposure & Metering A mode, marked M, in which the photographer sets aperture and shutter speed directly and the camera only advises.

Pinhole Camera Cameras, Formats & Systems mm A lensless camera that forms an image through a tiny aperture, giving infinite depth of field and extremely long exposures. d = √(2 × λ × f)

Program Mode Exposure & Metering An automatic mode, marked P, in which the camera selects both aperture and shutter speed while leaving other controls to the photographer.

Sensor Dust Sensors & Digital Capture Particles settling on the sensor's cover glass, which appear as dark spots in the image at small apertures.

Shutter Priority Exposure & Metering A semi-automatic mode, marked S or Tv, in which the photographer sets shutter speed and ISO while the camera chooses aperture.

T-stop Exposure & Metering T-stops A measured aperture value that accounts for the light a lens actually transmits, rather than the geometric ratio an f-number implies. T = N / √(transmittance)

Results for “Aperture”