Why are NASA astronauts (still) lying?

[ka9q]

I think it's been known a very long time. Simple observation of the pupil of the eye shows that it has both a very limited range and a fairly fast response time, neither of  which explain the wide dynamic range of the eye and the time it takes to dark-adapt to get that full range.

Furthermore, you lose the ability to dilate your eyes as you get older, just as you lose the ability to focus the lens. Certain drugs also stop down the iris, such as opiates. Yet your vision still maintains a pretty wide dynamic range.

[nomuse]

I wonder if some of the difficulty in describing the dynamic range of the eye is because it is not a simple system. I remember reading that the rods are concentrated in the center, the cones more present in the periphery, suggesting that different parts of the instantaneous field of vision have different sensitivities. But in the complete system, your eyes are rapidly scanning, presenting different parts of the retina to each part of the scene being imaged (and reconstructed piecemeal by the brain while doing so).

[Bob B.]

I remember reading that the rods are concentrated in the center, the cones more present in the periphery

It's the other way around - rods on the periphery and cones in the center.  Since rods are responsible for night vision, a person can seen fainter objects (such as when looking through a telescope) when using his/her peripheral vision.

[Dalhousie]

I think it's been known a very long time. Simple observation of the pupil of the eye shows that it has both a very limited range and a fairly fast response time, neither of  which explain the wide dynamic range of the eye and the time it takes to dark-adapt to get that full range.

Furthermore, you lose the ability to dilate your eyes as you get older, just as you lose the ability to focus the lens. Certain drugs also stop down the iris, such as opiates. Yet your vision still maintains a pretty wide dynamic range.

It wasn't covered when I did vision physiology as a biology student in the late 70s, 30 years after Clarke wrote his book.

[nomuse]

I remember reading that the rods are concentrated in the center, the cones more present in the periphery

It's the other way around - rods on the periphery and cones in the center.  Since rods are responsible for night vision, a person can seen fainter objects (such as when looking through a telescope) when using his/her peripheral vision.

Yah, I knew about the averted vision. But I can never seem to remember which one is the rod and which is the cone.

[Echnaton]

I remember reading that the rods are concentrated in the center, the cones more present in the periphery

It's the other way around - rods on the periphery and cones in the center.  Since rods are responsible for night vision, a person can seen fainter objects (such as when looking through a telescope) when using his/her peripheral vision.

Yah, I knew about the averted vision. But I can never seem to remember which one is the rod and which is the cone.

Another reason that averted vision works is that the further from the center of the eye the rods are, a single nerve pathway to the brain covers more and more rods.   The arrangement provides a more sensitive threshold for seeing at the expense of detail.

[Valis]

Yah, I knew about the averted vision. But I can never seem to remember which one is the rod and which is the cone.

A biology teacher told us to think about which one you'd rather have in hand when you are in dark. OK, that works better in Finnish, where the translations are more like "staff" and "peg", respectively.

[Al Johnston]

Cones are for Colour vision...

[dwight]

I am starting to get concerned about the wellbeing of of our fiesty OP? He promised us he was back, but there has been nary a peep since. Oh I do hope misfortune hasnt befallen him as I was ready to hear his convincing arguments about an alleged hoax...

[smartcooky]

I am starting to get concerned about the wellbeing of of our fiesty OP? He promised us he was back, but there has been nary a peep since. Oh I do hope misfortune hasnt befallen him as I was ready to hear his convincing arguments about an alleged hoax...

Drive By Spam!

[Andromeda]

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[Tedward]

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Oh, in shoals of them, think that was obvious from day one. Do you get shoals of sea birds? Or is it flocks, what about sea birds that dive under water to get at the fish, would they be a flock above the water and a shoal underneath?

[Tedward]

Cones are for Colour vision...

They are not.



They are for ice cream.....


OK. On my way out in shame.

[Zakalwe]

Yep...classic seagull poster...flaps in schreeching and dropping guano everywhere. Then drops out without any acknowledgement of his errors.

he's still over on YouTube trying to make out that the Hubble images are all fake. Sheesh...I wonder how nutcases like Weisbecker gets through life. Do they get confused over cartoons and wonder why the coyote manages to survive huge rocks dropping on his head?

[Tedward]

They get through life by avoiding where they will be accountable to people with real knowledge on a stage where they can be shown to be in error. They know this.