Science C4 Flashcards
aperture
the opening in a lens through which light passes to enter the camera; opens to different sizes to allow more or less light to enter the lens.
camera eye
The ability to record or recall detailed impressions of what one sees with photographic accuracy.
charge-coupled device (CCD)
the sensor used in digital cameras instead of film, used for serious astronomy; an electron device used for data acquisition; composed of many tine pixels, each of which records a buildup of charge to measure the amount of light striking it.
ciliary muscle
a ring of smooth muscle in the eye’s middle layer that adjusts the shape of the lens to allow for focusing objects at various distances on the retina
compound eye
- mostly in insects; use many small vision units called ommatidium. A tiny lens sits at the outside end of one end, touching a cone that directs light to the receptors within the tube walls.
cones
-cones detect colour
-Cones can’t function in low light, so all you can see are shades of grey.
Humans have three types of cones, Birds have five different types of cones
Nocturnal animals have MORE rods than cones in their retinas.
Remember: Rods = light, Cones = colour & detail
cornea
the transparent front part of the eye that covers the iris and pupil; helps refract light
diaphragm
a device for varying the effective aperture of the lens in a camera or other optical system.
far-sightedness
Farsightedness - cannot see close objects clearly
- lens is unable to refract light enough to focus on the retina
- image falls behind the retina
- corrected by converging (convex) lenses
film
When light strikes the film, the film changes chemically, forming an image.
iris
band of muscle in the eye that controls the size of the pupil and the amount of light entering the eye (similar to the diaphragm of a camera)
lens
Lens (eye): a transparent biconvex structure in the eye that helps to refract light to be focused on the retina
Lens (1): a transparent biconvex glass lens that refracts light
near-sightedness
Nearsightedness - cannot see distant objects clearly
- lens refracts light too much
- image falls in front of the retina
- corrected by diverging (concave) lenses
nocturnal
Nocturnal Animal Eyes - animals are awake at night.
-The eyes of nocturnal vertebrates allow them to collect as much light as possible in 3 main ways:
Pupil size
Tapetum Lucidum
More Rods
Nocturnal animals have MORE rods than cones in their retinas.
optic nerve
nerve that leads from the retina to the brain
- the optic nerve connects to the retina; this creates a blind-spot
Rods
Rods are highly sensitive to light,
rods are sensitive to even small amounts of light, they can function in very low light.
Rods are far more sensitive to low levels of light than cones.
phosphors
The phosphors in night vision googles glow green when the particles strike them. The person wearing the Goggles sees a glowing green image.
Rods
Rods are highly sensitive to light,
rods are sensitive to even small amounts of light, they can function in very low light.
Rods are far more sensitive to low levels of light than cones.
pixel
When a computer receives an image, it divides the picture up into small elements called pixels. Each pixel is assigned coordinates just like the row and seat numbers for a stadium seat. The resolution of an image refers to the number of pixels per unit area. Pixels are small elements that make up a picture.
pupil
opening in the eye that lets in light (dim = large pupils [dilated]; bright = small pupils [constricted])
resolution
Resolution: refers to the number of pixels per unit area
Imagine, two images are the same size
The one with more pixels will look best
More pixels = smaller sized pixels = Better Quality
= high resolution
Less pixels = larger sized pixels = Poorer Quality
= low resolution
retina
special lining on the back of the eye; when light hits the retina, receptor cells send messages to the brain, which translates them into an image
- rods - very sensitive to light; used in low-light conditions
- cones - can distinguish color; cannot be used in low-light conditions
shutter
lies behind the aperture. The shutter acts like a set of doors that open when you press the button to take a picture. The longer the shutter remains open, the more light enters the camera and strikes the film or sensor (CCD).
tapetum lucidum
(nocturnal animals) They also have a layer inside their eyes called the tapetum lucidum, which acts as a mirror to reflect light inside their eye.
is a layer of tissue in the eye of many vertebrates. Lying immediately behind the retina, it is a retroreflector.
Compare structures in the eye with the comparable camera structure.
Lens
Lenses
In camera, the lens moves closer/further from the film to focus. In your eyes, the lens changes shape to focus.
Pupil
Aperture
Tiny muscles in the iris change the size of the pupil like the aperture of a camera to control the amount of light getting into the eye. The aperture is the hole.
Iris
Diaphragm
The iris controls the size of the pupil and allows in certain amounts of light.
The diaphragm is what controls the aperture size.
Retina
Film
-When light strikes the film, the film changes chemically, forming an image.
-When light hits the retina, receptor cells send messages to the brain, which translates them into an image
Eyelid
Shutter
The shutter acts like a set of doors that open when you press the button to take a picture. The longer the shutter remains open, the more light enters the camera and strikes the film or sensor
An eyelid is a thin fold of skin that covers and protects an eye.
What are rods and cones and what are their similarities and differences?
Rods are highly sensitive to light,
rods are sensitive to even small amounts of light, they can function in very low light.
Rods are far more sensitive to low levels of light than cones.
-cones detect colour
-Cones can’t function in low light, so all you can see are shades of grey.
Humans have three types of cones, Birds have five different types of cones
Nocturnal animals have MORE rods than cones in their retinas.
Remember: Rods = light, Cones = colour & detail Simular:
-Rods and Cones are the photoreceptors of an eye.
- Both absorb light (photon) at a different wavelength.
- These are modified nerve cells.
- The process of phototransduction is same in both the cells.
Know the differences between near and far-sightedness and the types of lens required to correct each.
near = can't see things from far away, lens: concave far = can't see things close up, lens: convex
Be able to describe how night vision goggles work and what type of particles are involved.
In night vision goggles, light is focussed onto an image intensifier. Inside the intensifier, the light energy releases a stream of particles. These particles then hit a phosphor coated screen. The phosphors glow green when the particles strike them. The person wearing the Goggles sees a glowing green image.
In a digital image what is the photo image converted into?
pixels
What are the advantages of digital imaging?
The advantage of digital imaging is how quickly it can be moved from location to location. When you digitize images the image is sent through the camera which will turn it into digits, so when you reopen the image it will still be there whether it’s on a computer or camera. Another advantage of digital imaging is that digital cameras can be created to collect different parts of the electromagnetic spectrum.
How are compound eyes different than camera eyes?
Camera Eyes vs COMPOUND EYES
Are often found in insects
Each eye is made up of many smaller units.
Each individual unit is called an ommatidium
Describe how fish/bird/cat/owl eyes are different than human eyes?
The insect compound eye is like having lots of little eyes looking in different directions, but each little eye doesn’t see very well. The human eye can swivel, but it only looks in one direction at any given moment.
