Digital slr photography Exposure

Exposure In photography, exposure is the total amount of light allowed to fall on the film (or electronic sensor) during the process of taking a photographyIn photography, exposure is the total amount of light allowed to fall on the film (or electronic sensor) during the process of taking a photography It is measured in exposure value (ev) with higher values denoting more light entering the cameraIt is measured in exposure value (ev) with higher values denoting more light entering the camera It is controlled by three factors:It is controlled by three factors: Shutter SpeedShutter Speed Aperture (f-stop)Aperture (f-stop) Film Speed/Sensor Speed (ISO)Film Speed/Sensor Speed (ISO)

Shutter speed Shutter speed refers to how long the camera shutter opens to let light inShutter speed refers to how long the camera shutter opens to let light in Expressed in fractions of a second or full seconds (i.e. 1/60 th, 1/500 th, 1/1000 th, 2, 3)Expressed in fractions of a second or full seconds (i.e. 1/60 th, 1/500 th, 1/1000 th, 2, 3) The higher the denominator number, the faster the shutter; numbers above 1 are very slowThe higher the denominator number, the faster the shutter; numbers above 1 are very slow A faster shutter means that less light is let into the cameraA faster shutter means that less light is let into the camera

Shutter speed Fast shutter speeds are used to “freeze” actionFast shutter speeds are used to “freeze” action Sports or action photographySports or action photography Slow shutter speeds are used when a “blurring” effect is desiredSlow shutter speeds are used when a “blurring” effect is desired Classic waterfall shot, nighttime traffic shotsClassic waterfall shot, nighttime traffic shots

Fast shutter speed

Slow shutter speed

aperture Aperture (or f-stop) refers to a diaphragm that opens and closes to let more or less light into the cameraAperture (or f-stop) refers to a diaphragm that opens and closes to let more or less light into the camera Aperture settings are standardized and expressed as numbers such as 2.8, 4, 5.6, 8, 11Aperture settings are standardized and expressed as numbers such as 2.8, 4, 5.6, 8, 11 The lower the number, the wider the opening and the more light gets let into the cameraThe lower the number, the wider the opening and the more light gets let into the camera Apertures can affect the “depth of field”Apertures can affect the “depth of field” Refers to the areas of the photo that is in full focusRefers to the areas of the photo that is in full focus Wide apertures have a shallow depth of field (out of focus background)Wide apertures have a shallow depth of field (out of focus background) Narrow apertures have a large depth of field (everything is in focus)Narrow apertures have a large depth of field (everything is in focus)

Depth of field Shallow depth of field Full depth of field

Film speed (ISO) Film speed refers to the sensitivity of the film or image sensor to light – how fast is it able to capture the imageFilm speed refers to the sensitivity of the film or image sensor to light – how fast is it able to capture the image Expressed in ISO numbersExpressed in ISO numbers i.e. 50, 100, 200, 400, 800i.e. 50, 100, 200, 400, 800 The higher the number, the faster the image is capturedThe higher the number, the faster the image is captured Faster “film” tends to be grainierFaster “film” tends to be grainier

Iso settings Low ISO – clear image High ISO – digital noise

Setting exposure Automatic ( AUTO ) – Camera decides settingsAutomatic ( AUTO ) – Camera decides settings Programmed Auto ( P ) – you change the shutter speed and aperture without changing the exposureProgrammed Auto ( P ) – you change the shutter speed and aperture without changing the exposure Shutter Priority ( S ) – you set the shutter speed (higher is faster)Shutter Priority ( S ) – you set the shutter speed (higher is faster) Aperture Priority ( A ) – you set the aperture for wide or narrow depth of fieldAperture Priority ( A ) – you set the aperture for wide or narrow depth of field Manual ( M ) – you select any shutter speed and aperture settingManual ( M ) – you select any shutter speed and aperture setting

Under & Over exposure Cameras set exposure based on 18% grey reflectivenessCameras set exposure based on 18% grey reflectiveness Overexposure occurs when too much light is let into the cameraOverexposure occurs when too much light is let into the camera Picture is too brightPicture is too bright Underexposure occurs when not enough light is let into the cameraUnderexposure occurs when not enough light is let into the camera Picture is too darkPicture is too dark

exposure Overexposed Underexposed

Exposure situations There are a couple situations that pose difficulties when taking photographsThere are a couple situations that pose difficulties when taking photographs Subject is in front of a bright window – hard to get an even exposure because subject is too dark and background is too lightSubject is in front of a bright window – hard to get an even exposure because subject is too dark and background is too light Taking pictures on snow or ice – camera is fooled and snow/ice may look greyishTaking pictures on snow or ice – camera is fooled and snow/ice may look greyish

Exposure situations Use “fill flash” to help “Stop down” a step or two to let more light into the camera