What are the differences between cones in the periphery of the retina and those in the center?
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The short answer is that there is no difference on a cellular level.
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Each of the eyes are slightly recessed, and each eye points in a slightly different direction.  This makes it so that depending on which eye detects the most light, the insect is able to determine the direction of the light.  Humans, by contrast, find the location of light by having a lens which focuses the incoming light on the photo-sensitive retina at the back of the eye.
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Your eye has a converging lens, so if you ever played with magnifing glass you know the effect of such lens. It concentrats all the light in one dot, which is on the back of the retina.
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That really is a fun and interesting question!!!\n\nOur cones are not necessarily identical, which means that out perceptible gamut will not map identically on the xy plane. (Click on the link from Discover Labs listed below for pictorial examples of these differences, for example in color blindness) \n\nHowever the difference for most of us is so insignificant that it doesn't matter. \n\nThat is what professionals like photographers, artists and cinematographers, etc. base their success in their professions on. Also remember that colors are not arbitrary but are determined by their wavelengths. There may be some other issues on a quantum level, More...\n\nYou'll find some fun, interesting and easy to understand theory in addition to great explanatory  illustrations here at this link:\n\nhttp://www.discover.uottawa.ca/~aelsawah/csi4133/Lab02.htm
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The other answers are okay as far as they go.  However, the unique feature of the retinal ganglion cells is that they are the only cells (i.e. defined as the cells) that project out of the retina to the brain.  The other cells in the retina make their connections within the retina.
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1) its optical centre\n2) 1/2 cm\n3)converges, diverges\n4)perpendicular incidence of light\n5)ciliary muscles
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The light was not reflected.  Think about this:  if you look into someone's eye (through their pupil), can you see the back of their eye?  No.  The light is actually absorbed by special cells in the retina called photoreceptors (rods and cones).  These cells start the transmission of light information to the brain.
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Haven't you noticed that violet seems dim compared to blue? That's because only the blue cones are reporting it, but the green cones report a little when blue light hit them.
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To elaborate on the previous response: Color is merely your brain's interpretation of light (electromagnetic radiation in the visible spectrum) entering your eye. A difference in color corresponds to a difference in the light's wavelength. And just as there are an infinity of numbers between 0 and 1 (fractions), you could also technically say there are an infinite number of colors between the shortest wavelength of visible light and the longest. This is the answer you'd get from a physicist.\n\nBut, a physiologist/neurologist might have a different answer. As I stated, color is an interpretation of the chemical reaction between light and the rods and cones in the back of your eye. The fact that it's an interpretation and the fact that we can't detect very small differences in wavelength suggests that there is a much smaller set of colors that we, as humans, could define given our very limited built-in equipment (our eyes). Even among humans it varies though, I have no idea what my girlfriend is talking about sometimes. It's not for lack of trying, my eyes/brain (as with many guys) is capable of detecting a smaller set of colors than girls. Is her set more valid than mine?\n \nAnd I'm sure an artist and a poet would tell you something completely different :)
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Different photoreceptors respond more or less strongly to different wavelengths (colours) of light. Digital cameras use more than one type of photodector for each pixel of the picture. By comparing the strengths of the signals from different detectors you can tell what colour the pixel should be.\n\nFilm cameras do the same thing, but use different chemicals in the film instead of photodectors. The different chemicals respond to different wavelengths of light.
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There are two types of light receptors in the human eye - rods and cones.\n\nRods are very sensitive to light, but don't see color well.\n\nCones require brighter light to work, but they are used for color vision.\n\nThere are three types of cones... one for each primary color.\n\nIn red-green color blindness a genetic defect causes the cones that detect green light to be missing or to not work.  The result is vision with no green component.
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You're right, Red+Blue=Violet.  The light doesn't have to interfere.  You don't have violet cones in your eye (you have 3 that are more or less maximally receptive at red, green, and blue)... your brain interprets equal amounts of blue and red neurons firing as the color violet.  It also interprets equal amounts of red and green light as yellow.  \n\nNow you should wonder what happens when light of 400nm hits your eye.  You don't have violet cones, but this light is not in an energy eigenstate, so you can express it as a linear combination of red and blue wavelengths... the result is that 400nm light will excite red and blue cones in equal amounts so you view it as violet.
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speed smear or high speed smear\n\nIt should be noted that this effect is mostly in your peripheral vision
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This is different than what is normally called the "blind spot".  That is a spot off to the side of your vision where all of the optic nerve enters the eyeball.  A good demonstration of the blind spot can be found in the link below.  You can even cut & paste the demo into paint and change the color of the spot to see how color affects it.\n\nWhat you're experiencing is a more subtle phenomenon.  Cones (think ice cream cone) sense color, while rods (think magician's rod) sense only black and white.  Rods are don't work well in bright light, but work very well in low light situations such as when all the lights are turned off, but there is still light from an outside street lamp.  OTOH, cones work well in bright light, but stop working almost completely in low light.  \n\nAnother aspect of this is that cones only cover central vision, whereas rods cover the entire retina.  There are also fewer rods in the central vision.\n\nSo.  You are in a dark room or on a dark street.  The light from the computer screen/car ahead of you knock out the rods in your central vision but not the peripheral vision.  Then the light goes out and the cones stop working while the central rods haven't gotten started yet, but the peripheral vision is still working well.  So you can see things out of the corner of your eye but it disappears when you look straight at it.  Boo!  It must be a ghost!
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study area. It is the only place where eyes are highly focused/concentrated. Reading under less intensity of light can affect your eye sight.
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There are two basic differences.\nThe main one is the number of rods at the back of the eye. These minute rods are very sensitive to light. Nocturnal animals have many more of these than humans.\nThe second reason is that nocturnal animals can open their pupil to a much greater extent and so let in more light.\nThe quote below refers to owls but is just as valid for animals.\n\n"The eyes themselves are modified in nocturnal species to improve sensitivity in low light intensities. This is achieved by several adaptations; they are very large, a Snowy Owl weighs as much as our own, secondly they are tubular rather than round giving a relatively large cornea in proportion to the overall size of the eye which enables more light to enter the eye. The light passes through the pupil, (which can be closed by the iris to a small pinprick in bright light, or, opened so wide that virtually no iris is visible at night) to the lens. This is large and convex causing the image to be focused nearer to the lens hence retaining maximum brightness. One draw back is that owls are long sighted and cannot focus on objects, which are to close, tactile bristles around the beak partially compensate for this. The tubular shape also gives a comparatively large retina size which is packed full of light sensitive rods, about 56,000/ square mm. in the Tawny Owl. These rods are far more sensitive than cones at low light levels The phenomenal light gathering properties of the owls eye is further enhanced in many species by a reflective layer behind the retina called the tapetum lucidum reflects back onto the rods any light that may have passed through the retina without hitting one the first time. Tawny owls would appear to have the best developed eyes of all the owls, indeed of all vertebrates, being probably about 100 times more sensitive at low light levels than our own. To put this into perspective, a Tawny Owl can locate prey several metres away by the light of just one candle about 1700 feet away!"
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Portion(s) of the retinal field that are non-functional (i.e., blind areas). Scotomas may be central, if caused by macular or optic nerve disease, or peripheral if the result of chorioretinal lesions or retinal holes.