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    Re: Telescope danger to sight. Was: Venus transit ...
    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
    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
    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.
    contact George Huxtable by email at george---.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.

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