Quote:
Originally Posted by DuckieTigger
@AnotherCat: You are forgetting that the human eye has an iris that regulates how much light hits the retina. Outdoors does not necessarily mean more light hits the retina, only because it is brighter.
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No I did not and I wonder what makes you so determinedly claim so when you haven't yet asked if I had forgotten it or not
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The pupillary response is only capable of regulating some of the range of light intensities that we normally encounter. I am not going to tell you why because you will only want to pick holes in what I say rather than ask for clarifications if needed. So I will set you a little task which I am sure you will undertake if you have a genuine interest. All information needed for the task will be found on the internet.
1. Get the typical human eye diameters for maximum and minimum dilation. Calculate the ratio of the areas (light intensity passed is in the same ratio). Let's call that A.
2. Get the typical values for the ends of the easily comfortable range of light intensities the eye can manage (e.g. compare a lit room with a bright sunny day) and calculate the ratio of the intensities. Let's call that R.
Now investigate and report back as to whether or not R is very much different to A. Comment on what this means with respect to how much the pupil can control the intensity of light entering the eye when going between differing light intensity environments. If you find that the pupil cannot effectively manage the light intensities identify the other mechanisms that are used.
Also investigate and report back why the pupil response differs between individuals and according to situations, and the significance of those things when going between differing light intensity environments.
Then report back as to the veracity of your claim that I had "forgotten that the human eye has an iris that regulates how much light hits the retina". State whether or not what you have found means that it is safe to assume that the pupil will contract sufficient to alleviate the much higher intensity of blue light outside in comparison to that from a typical device.
As can be seen, if I had to explain all of that stuff (even just to the limits of my very small knowledge of a complicated subject that crosses several sciences) it will be fairly lengthy and tiresome. So it seems to me it is fair enough for me to just give you the leads into being able to explain it to yourself and ask you to report back your conclusions.
{For others, DuckieTigger is likely to find that A typically equals around 15 or so and R in excess of 250. So the pupil can control light intensities over a ratio of around 15:1 whereas the change in environmental light levels we regularly traverse is in the ratio in excess of 250:1}