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Re: Telescope danger to sight. Was: Venus transit ...
From: George Huxtable
Date: 2004 May 13, 22:07 +0100
From: George Huxtable
Date: 2004 May 13, 22:07 +0100
Jared Sherman said- "Tha may be why the generic advice is simply never to look at it rather than trying to explain exactly how and when the threshold for dmaage is passed." and perhaps I was being unduly hard on him in responding-- "It is anti-scientific obscurantism at its worst! Although it may indeed be true (and to me now, the evidence is accumulating) that a telescope does NOT increase the intensity of the Sun's image on the retina, only its size, it seems that Jared would rather not know that." That was indeed somewhat over-the-top and caused him to reply- "Honestly, George, I don't know how you draw these assumptions about what I might prefer. Asking me directly would doubtlessly be more reliable than making assumptions." Which is fair enough. If I misrepresented Jared's view, then I'm sorry. It's just that UNDERSTANDING provides the sort of illumination that never blinded anyone. If we can understand what's going on, then that provides a rational way to assess what is safe practice and what isn't. Ken Gebhart asked an interesting question as follows- "Are there any anecdotal cases of eye damage from sextants that anyone on the list can personally attest to?" And so far, on this list, with all its years of experience of sextant use, not one member has responded. I think that might help us all to put this matter into perspective, and help us to separate the science from the superstition. Please note that I am NOT advocating that anyone should look directly at the Sun, either directly or through a sextant telescope. Care is certainly called for. But perhaps some understanding of the matter might dispel the belief that an optical accident will necessarily result in instant blinding, before the blink-response has had time to work. George. ================================================================ contact George Huxtable by email at george@huxtable.u-net.com, by phone at 01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. ================================================================