LensesContain both convex and concave lenses
LensesMany concave and convex lenses, called elements are grouped together to produce a specific magnification and correct color aberrations
LensesEach element adds the chance for reflection in the lensCalled lens flare
Focal LengthA measurement of the magnifying power of a lens
Focal LengthAs magnification increases, field of view decreases50mm - normal film lens
Prime and Zoom LensesPrime Lens - fixed focal lengthZoom - can adjust the focal length (magnification)
Focal Length - Normal Lens
Focal Length - Normal Lens
ExposureImage sensor needs only a tiny bit of light to expose an image
ExposureToo much light, the picture is overexposedToo little light, the picture is underexposed
ExposureA camera has two mechanical mechanisms for controlling exposure:Aperture ShutterShutter, Aperture (in the lens)
Exposure - ApertureAn expandable opening like the iris of your eye that controls how much light passes through the lens
Exposure - ApertureUsually constructed of thin, sliding, interlocking metal plates
Exposure - ApertureAs you close the iris down to a smaller aperture, it stops more light from reaching the image sensor
Exposure - ApertureThe size of the aperture is measured in stops or f-stopsThe higher the f-stop rating, the more light the aperture is stopping
Exposure - ApertureLens speed is determined by how wide its iris or aperture can open.The wider the aperture, the faster the exposure can be.
Exposure - Fast lensesA lens that can be opened to f1.8 is much faster than a lens that can only open to f4.Can shoot in lower light and have a wider range of aperture settings - more creative freedom.More difficult to build - more expensive
Exposure - ApertureAperture and shutter speed are interrelated
Exposure - ShutterOpens and closes very quickly to control how much light passes through to the image sensor
Exposure - ShutterShutter speed is a measure of how long the shutter stays open, measured in seconds and fractions of seconds
Exposure - ReciprocityMeans that many different shutter speed/aperture settings all yield the same exposure1/30 @ f161/60 @ f111/125 @ f8
Exposure - ReciprocityIf shutter speed or aperture is shifted in one direction, the other is shifted in the opposite direction the same amount.
Exposure - ReciprocityIf a proper exposure calls for 1/60 sec. and f16, what should the f-stop be if the exposure time was decreased to 1/125?
Exposure - ReciprocityISO can also affect shutter speed and/or aperture settings
Exposure - ReciprocityEvery time the ISO value is doubled, it makes the image sensor twice as sensitiveEach value = 1 stop
Exposure - ReciprocityThe higher the ISO value, the more noise there is in the picture, similar to grain in an image made from film with a higher ISO.