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| The Human Eye - Our Prime lenses? | |
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| Tweet Topic Started: Mar 1 2009, 11:44 PM (413 Views) | |
| Mino | Mar 1 2009, 11:44 PM Post #1 |
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Alpha Elite Member
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Quote from From Wikipedia, the free encyclopedia The human eye is a significant human sense organ. At least 80% of the data that reaches the brain is collected by the eye. The eye allows human beings vision which includes color differentiation and distance or depth. The human eye has a 200° viewing angle and can see 2.7 million colors. Color blindness is a defect that prevents people from differentiating between two or more colors. Dynamic range ----------------------- The retina has a static contrast ratio of around 100:1 (about 6 1/2 stops). As soon as the eye moves (saccades) it re-adjusts its exposure both chemically and by adjusting the iris. Initial dark adaptation takes place in approximately four seconds of profound, uninterrupted darkness; full adaptation through adjustments in retinal chemistry (the Purkinje effect) are mostly complete in thirty minutes. Hence, a dynamic contrast ratio of about 1,000,000:1 (about 20 stops) is possible. The process is nonlinear and multifaceted, so an interruption by light merely starts the adaptation process over again. Full adaptation is dependent on good blood flow; thus dark adaptation may be hampered by poor circulation, and vasoconstrictors like alcohol or tobacco. The eye includes a lens not dissimilar to lenses found in optical instruments such as cameras and the same principles can be applied. The pupil of the human eye is its aperture; the iris is the diaphragm that serves as the aperture stop. Refraction in the cornea causes the effective aperture (the entrance pupil) to differ slightly from the physical pupil diameter. The entrance pupil is typically about 4 mm in diameter, although it can range from 2 mm (f/8.3) in a brightly lit place to 8 mm (f/2.1) in the dark. Whereas the link article; The maximum aperture of a human eye is about f/2.1 & minimum aperture is about f/11 or f/8.6 Here's a interesting article where someone else did all of the research to find out human eye answers. Link |
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| Stvc | Mar 1 2009, 11:56 PM Post #2 |
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Newbie
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Walao..Chim... lol |
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My Flickr | |
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| s.khai | Mar 2 2009, 12:05 AM Post #3 |
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my inspiration, my journey...
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i only read the words. i skipped the numbers..ive got number blindness LOL |
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if you think you're good, remember, the best are still learning... s.khaiphotos my multiply - my picture page my facebook - my face in my book my flickr - my flickr page | |
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| Ming | Mar 2 2009, 12:22 AM Post #4 |
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90609866
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Bro Mino , i don't think its suitable for Newbies like me ...
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Ask ... Absorb ... Equip ... Execute N E X with M I N G HERE ! A P - Ming HERE ! Macro-Ming HERE ! Pano-Ming HERE ! Food ! Food ! Foods ! HERE | |
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| Mino | Mar 2 2009, 12:53 AM Post #5 |
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Alpha Elite Member
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The human eye can see 2.7 million colors. How about CCD/CMOS sensors? Predict in future, DSLR manufacturers will start making 16 bit sensors (now; advance 14bit or standard 12bit.) This is binary arithmetic. Every additional bit adds one more power of 2. 2 power 8 = 256 levels 2 power 12 = 4 096 levels 2 power 14 =16 384 levels 2 power 16 =65 536 levels 2 power 32 =4 294 967 296 levels Mostly, all monitors are only 6bit/8 bit panel so cannot possibly show the difference between 12 and 14 bit. Obviously as monitors and printers improve, the difference will become easier to see. It can hardly be seen on-line now even with TIFF, because better monitors are 10 or 12 bit only. But technology advances so fast, it is good we can make 14 bit RAW now. In 3-4 years the difference will be easy to justify (in 100% crops). well... the Sony A900 - which I would definitely see in the "semi-pro or professional" range - runs with 12 bit only - and it does not hurt. Differences coming from the quality of the lenses used still seem to be much bigger than 12 or 14 bit. Also, although 14 bits may be overkill now, if/when sensors improve dynamic range, the extra bits will help keep the tone separation fine enough for printing without the "steps" being visible. In other words if you increase DR by just two stops, you wind up with the same gap between each brightness level as you do with 12 bits. |
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| yannh | Mar 2 2009, 09:50 AM Post #6 |
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Alpha Sniper Member
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Wonderful creation of God! Man made lenses & sensor is still so far apart..... I always amaze with the ISO level that our eyes has..... wonder how much is that.... |
| Sony Alpha. | |
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8:43 AM Jul 11