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Pinhole CamerasPinhole CamerasConverging & Diverging Converging & Diverging
LensesLenses
Pinhole ImagePinhole Image
Pinhole CameraPinhole Camera
Image is upside down and left to right reversed
Size of image is determined by distance from pinhole to screen/film
The smaller the pinhole, the clearer the image & the dimmer the image
Pinhole Camera PicturePinhole Camera Picture
Pinhole Camera PicturePinhole Camera Picture
Pinhole Viewing of Partial Pinhole Viewing of Partial EclipseEclipse
Shape of a LensShape of a Lens
Types of LensesTypes of Lenses
Convex Lens TermsConvex Lens Terms
Three Rays to Locate Three Rays to Locate ImageImage
Ray parallel to axis bends through the focus. Ray through the focus bends parallel to axis. Ray through center of lens passes straight
through.
Characterizing the ImageCharacterizing the Image
Images are characterized in the following way– Virtual or Real– Upright or Inverted– Reduced, Enlarged, Same Size
Object Beyond 2fObject Beyond 2f
Image is– Real– Inverted– Reduced
Object at 2fObject at 2f
Image is– Real– Inverted– Same size
Object Between 2f and fObject Between 2f and f
Image is– Real– Inverted– Enlarged
Object at FObject at F
No Image is Formed!
Object Closer than FObject Closer than F
Image is– Virtual– Upright– Enlarged
Converging Lens ImagesConverging Lens Images
Eye OpticsEye Optics
Accommodation – Shockwave Applet
Normal EyeNormal Eye
In the normal eye, the cornea/lens system project an inverted, “focused” image on the retina – which is the screen.
Myopia -- NearsightednessMyopia -- Nearsightedness
In a nearsighted eye, the image is “focused” in front of the retina.
A diverging (concave) lens is used to cause the image to be “focused” at the retina.
Hyperopia -- Hyperopia -- FarsightednessFarsightedness
In a farsighted eye, the image is “focused” behind the retina.
A converging (convex) lens is used to cause the image to be “focused” at the retina.
AstigmatismAstigmatism
In astigmatism, the cornea is irregularly shaped & the light focuses at multiple points.
The result is blurry or multiple images.
Concave Lens Ray TracingConcave Lens Ray Tracing
Ray parallel to axis refracts as if it comes from the first focus.
Ray which lines up with second focus refracts parallel to axis.
Ray through center of lens doesn’t bend.
Image Formed by Concave Image Formed by Concave LensLens
Image is always– Virtual– Upright– Reduced
Concave Lens Image Concave Lens Image DistanceDistance
As object distance decreases– Image distance
decreases– Image size increases
Image CharacteristicsImage Characteristics
CONVEX LENS – IMAGE DEPENDS ON OBJECT POSITION– Beyond F: Real; Inverted; Enlarged,
Reduced, or Same Size– Closer than F: Virtual, Upright, Enlarged– At F: NO IMAGE
CONCAVE LENS – IMAGE ALWAYS SAME– Virtual– Upright– Reduced