pinhole cameras converging & diverging lenses. pinhole image

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