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Apertures and f-stops 2009 Len Cook

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Apertures and f-stops Sun Protection Factor (SPF) Youve heard of SPF, havent you?

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Apertures and f-stops Sun Protection Factor (SPF) Youve heard of SPF, havent you?

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Apertures and f-stops Sun Protection Factor (SPF) Youve heard of SPF, havent you?

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Apertures and f-stops Sun Protection Factor (SPF) Youve heard of SPF, havent you?

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Basic types of cameras Single Lens Reflex (SLR)

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Basic types of cameras Single Lens Reflex (SLR)

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Basic types of cameras Single Lens Reflex (SLR)

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Basic types of cameras Single Lens Reflex (SLR)

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Basic types of cameras Single Lens Reflex (SLR)

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Whole stops, third-stops Familiar apertures from 35mm equipment: 1.4 2 2.8 4 5.6 8 11 16 22 32

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Whole stops, third-stops Familiar apertures from 35mm equipment: 1.4 2 2.8 4 5.6 8 11 16 22 32 SPF-STOPS! YEAH!

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Whole stops, third-stops Familiar apertures from 35mm equipment: WHOLE STOPS 1.4 2 2.8 4 5.6 8 11 16 22 32

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Whole stops, third-stops Familiar apertures from 35mm equipment: THIRD STOPS 4 4.5 5.0 5.6 6.3 7.1 8 9 10 11

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Whole stops, third-stops 4 4.5 5.0 5.6 6.3 7.1 8 9 10 11 From 4 to 5.6 is one stop. From 4.5 to 6.3 is one stop!

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Whole stops, third-stops Your cameras have dials or buttons to change apertures. Three clicks of a dial is one stop. Three button presses make one stop. That is, if you have your camera set up to show third-stops. Many cameras can also be set to show half- stops.

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Apertures

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F-stop selection

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Wide open = full aperture

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Manual lever moves the diaphragm

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Pentagon-shaped aperture

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Minimum aperture

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Circular aperture

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Many smoothly curved blades

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Ring around the lens

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Setting 35mm camera f-stops

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f/8 and be there!

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Basic types of cameras -- shutters

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A camera shutter is a set of parts that can move quickly out of the way to allow light to hit the film or the digital sensor. When the parts are out of the way the shutter is in the open position. All modern camera shutters are controlled by timers to close after a pre-determined interval. Visual examples follow the text.

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Basic types of cameras -- shutters Shutter parts are usually curtains or blades. 35mm camera shutters were made of flexible fabric curtains for the first 50 years they were manufactured. Now all camera shutters are made of movable blades or disks.

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Basic types of cameras -- shutters Leaf shutter Mechanical device, but may be controlled electronically Quiet Flash synchronization at all speeds Open Close

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Basic types of cameras -- shutters Between-the-lens leaf shutter and diaphragm Shutter blades NO HOLE! Diaphragm blades HOLE!

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Basic types of cameras -- shutters Focal plane shutter Mechanical device, but may by controlled electronically Allows short exposure times, e.g. 1/4,000 sec. Built into camera body, so one shutter works with all lenses that fit the body Made of curtains that travel horizontally or vertically, not both.

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Basic types of cameras -- shutters Focal plane shutter Shutter is closed, ready

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Basic types of cameras -- shutters Focal plane shutter The first curtain rises to allow light to reach the film.

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Basic types of cameras -- shutters Focal plane shutter Second curtain closes

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Depth of field Step into the garden to look at blossoms two different ways.

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Depth of field

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Lenses NEVER focus anything perfectly. They just focus well enough to make our optic nerves (eyeballs) happy. Lenses turn points of light into little circles on the film. Those are called the circle of confusion. How appropriate, eh? Lenses for 35mm film and digital sensors make circles 0.03mm in diameter. Thats about one TENTH the diameter of a human hair.

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LensFilm Subject in sharp focus X Focused on film Not focused on film In the picture, but not sharp Large aperture

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Depth of field LensFilm Subject in sharp focus X Here is the size of The Circle of confusion Not focused on film In the picture, but not sharp

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Depth of field LensFilm Subject in sharp focus X OH LOOK! The light rays FIT inside the circle of confusion Not focused on film In the picture, AND NOW ITS SHARP! SMALL aperture

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