Lenses Contain both convex and concave lenses

Lenses Many concave and convex lenses, called elements are grouped together to produce a specific magnification and correct color aberrations

Lenses Each element adds the chance for reflection in the lens Called lens flare

Focal Length A measurement of the magnifying power of a lens

Focal Length As magnification increases, field of view decreases 50mm - normal film lens

Prime and Zoom Lenses Prime Lens - fixed focal length Zoom - can adjust the focal length (magnification)

Focal Length - Normal Lens

Exposure Image sensor needs only a tiny bit of light to expose an image

Exposure Too much light, the picture is overexposed Too little light, the picture is underexposed

Exposure A camera has two mechanical mechanisms for controlling exposure: Aperture Shutter Shutter, Aperture (in the lens)

Exposure - Aperture An expandable opening like the iris of your eye that controls how much light passes through the lens

Exposure - Aperture Usually constructed of thin, sliding, interlocking metal plates

Exposure - Aperture As you close the iris down to a smaller aperture, it stops more light from reaching the image sensor

Exposure - Aperture The size of the aperture is measured in stops or f-stops The higher the f-stop rating, the more light the aperture is stopping

Exposure - Aperture “Lens speed” is determined by how wide its iris or aperture can open. The wider the aperture, the faster the exposure can be.

Exposure - Fast lenses A 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 - Aperture Aperture and shutter speed are interrelated

Exposure - Shutter Opens and closes very quickly to control how much light passes through to the image sensor

Exposure - Shutter Shutter speed is a measure of how long the shutter stays open, measured in seconds and fractions of seconds

Exposure - Reciprocity Means that many different shutter speed/aperture settings all yield the same exposure f16 f11 f8

Exposure - Reciprocity If shutter speed or aperture is shifted in one direction, the other is shifted in the opposite direction the same amount.

Exposure - Reciprocity If 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 - Reciprocity ISO can also affect shutter speed and/or aperture settings

Exposure - Reciprocity Every time the ISO value is doubled, it makes the image sensor twice as sensitive Each value = 1 stop

Exposure - Reciprocity The 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.