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Old 09-10-2017, 09:16 PM   #21
Purple Haze
 
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Default Re: What if you replaced all cones with rods?

Long before Lasik was a thing, I had a friend with 20/5 vision. He could read a newspaper at 20'.
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Old 09-10-2017, 09:32 PM   #22
Flyndaran
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Default Re: What if you replaced all cones with rods?

That's slightly better than the best possible assuming human sized pupils due to physics.
He was probably not seeing every letter clearly, but partly guessing based on rules of language.
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Old 09-11-2017, 12:10 AM   #23
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Default Re: What if you replaced all cones with rods?

Quote:
Originally Posted by Purple Haze View Post
Long before Lasik was a thing, I had a friend with 20/5 vision. He could read a newspaper at 20'.
Max possible given human pupil size is around 20:10.
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Old 09-11-2017, 04:19 AM   #24
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Default Re: What if you replaced all cones with rods?

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Max possible given human pupil size is around 20:10.
That's what Ted Williams had, which was considered a medical marvel when he had his military physical for WWII.
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Old 09-11-2017, 07:54 AM   #25
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Default Re: What if you replaced all cones with rods?

Let me add a recommendation: Animal Eyes, by Michael F. Land and Dan-Eric Nilsson (Oxford University Press). It was my single most valuable source for writing GURPS Powers: Enhanced Senses. If you want to write an actual book, you might as well read a systematic survey rather than going by the bits and pieces various of us happen to know and contribute.
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Old 09-11-2017, 11:20 AM   #26
sir_pudding
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Default Re: What if you replaced all cones with rods?

My right eye is something better than 20:20. For years I thought my left eye needed correction because my vision is noticeably poorer there, and I always couldn't understand why I was always just waived on after eye tests because I felt certain that I must have failed the left eye portion by being unable to read lines that were fine for my right eye. Turns out my left eye is fine, but my right eye is closer to 20:15. I think this actually has a lot to do with my migraines.

Edit: I can read line 10 mostly on the Schelling chart with my right eye, which I think means that my vision there is between 20/15 and 20/10 but I am having trouble finding explanations for lines 9-11 online.

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Old 09-11-2017, 11:37 AM   #27
whswhs
 
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Default Re: What if you replaced all cones with rods?

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My right eye is something better than 20:20. For years I thought my left eye needed correction because my vision is noticeably poorer there, and I always couldn't understand why I was always just waived on after eye tests because I felt certain that I must have failed the left eye portion by being unable to read lines that were fine for my right eye. Turns out my left eye is fine, but my right eye is closer to 20:15. I think this actually has a lot to do with my migraines.
Your average mammal has around 20:150-20:200, I think, or -5 to -6. But I went with -4 for the new Bad Sight in Enhanced Senses, to be compatible with other forms of Bad Sight.
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Old 09-11-2017, 11:53 AM   #28
sir_pudding
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Default Re: What if you replaced all cones with rods?

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Your average mammal has around 20:150-20:200, I think, or -5 to -6. But I went with -4 for the new Bad Sight in Enhanced Senses, to be compatible with other forms of Bad Sight.
20:200 (for humans) is legally blind, which might reasonably be a worse condition then either form of Bad Sight (Bad Sight plus a Minor Handicap quirk giving an additional -2 to near or far vision?) .
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Old 09-11-2017, 12:12 PM   #29
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Default Re: What if you replaced all cones with rods?

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Originally Posted by sir_pudding View Post
20:200 (for humans) is legally blind, which might reasonably be a worse condition then either form of Bad Sight (Bad Sight plus a Minor Handicap quirk giving an additional -2 to near or far vision?) .
Legally blind means eligible for compensation as if blind, not being actually unable to see. GURPS bad sight is quite severe, it arguably reaches the definition of legally blind.

In terms of actual effects, at a range of 1 yard, 20:20 vision has a resolution of 0.01" (about 1 pixel on a typical monitor). Having a resolution of merely 0.1" will not especially affect anything most animals care about, though for animals with binocular vision it does affect parallax detection (range uncertainty of a couple inches at a range of 1 yard).
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Old 09-11-2017, 12:16 PM   #30
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Default Re: What if you replaced all cones with rods?

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Legally blind means eligible for compensation as if blind, not being actually unable to see. GURPS bad sight is quite severe, it arguably reaches the definition of legally blind.
20:200 is closer to -6 than -4.
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