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    Re: Eyesight dangers using telescopes
    From: Frank Reed
    Date: 2009 Jun 26, 18:38 -0700

    Bill Morris, you wrote:
    "From a quick scan of the medical literature on solar retinopathy it seems 
    that you can get retinal burns without using a telescope or gazing at the sun 
    while under the influence of "substances". Several cases are reported of 
    people simply sunbathing at low latitudes in bright sunlight."
    
    Really? That's amazing! I would have thought that evolution would have 
    eliminated this. That is, unaided vision should be relatively immune to 
    damage from the Sun for "normal" people. Are we talking about fair-skinned 
    northern Europeans lying on equatorial beaches? That's probably info not 
    recorded in the abstracts in the medical papers... I've seen a couple of 
    articles stating that repeated glimpses of the Sun over a course of some 
    hours are associated with damage. I could imagine all-day sunbathers falling 
    into that category. Maybe they even train themselves, unintentionally, to 
    ignore the reflex to look away...
    
    You wrote:
    "I had assumed that the light intensity at the retina was greater, without really thinking about it."
    
    And I certainly assumed as much until I saw the details worked out 
    theoretically many years ago AND conducted some experiments to make sure it 
    wasn't all "smoke and mirrors". It's certainly counter-intuitive, and there 
    are plenty of specific cases of this that still confuse me.
    
    -FER
    
    
    
    
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