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I'd like to see a source to the claim that at 40, fully fifty percent of the light that reaches your eye didn't get to the retina.
by aetherson 11y ago
I'd like to see a source to the claim that at 40, fully fifty percent of the light that reaches your eye didn't get to the retina.
- trurl 11y agoYeah, I'm only a couple years off from forty and I'm pretty sure my vision is not nearly fifty percent dimmer than twenty years ago. Certainly my glasses prescription has changed slightly, but that is more about redirecting the light.
- coldtea 11y agoHaving 50% less light getting to the retina is not necessarily that it looks 50% dimmer subjectively. E.g. it's not like having a dimmer for your room lights at 100% and 50%. I guess it's more like a 1-stop difference in photography (where again, half as much light hits the film/sensor from one stop to the next). Here's an example with half the 50% less light hitting the sensor between the two pictures. It's not as dramatic as you expect (except in the "depth of field", e.g. how focused stuff is): http://www.adammoroz.com/wp-content/uploads/2014/10/Untitled-1.jpg http://www.adammoroz.com/wp-content/uploads/2014/10/Untitled...
- good_gnu 11y agohttp://lrt.sagepub.com/content/26/2_IEStrans/95.abstract http://lrt.sagepub.com/content/26/2_IEStrans/95.abstract The abstract of this paper offers a data point that is consistent with the claim. For the purposes of this discussion, it is safe to say that the claim is not too far off.
- coldtea 11y agoThat's like one "stop" of light in photographic terms (each stop is half the light at the previous one). It might sound too much of a difference, but it's not that apparent (you can try changing an f-stop on a camera for comparison). (Probably there's some logarithmic sensing involved).