RASC Hamilton Transit of Venus

[Mark Kaye]

On 12-5-12 11:47, Andy Blanchard wrote:
> London just did whole thing on welders glasses and they are clearly too dangerous.
>    
    The common grade of welder's filters that all suppliers have and 
most welders use is #12.  While this is very thick and hard to see 
through, it is not enough to safely filter the Sun.  #14, a specialty 
filter for heavy duty arc welding is strong enough to safely filter the 
Sun, but it is not readily available.
    Welders filters are only safe to use as a cover for one's eyes to 
view the sun without optical aid.  They are not suitable for use in 
front of a telescope for a number of reasons.  They are not optical 
grade and will distort the image.
    Given the cost and difficulty of finding #14 welder's filters, it 
would be a much better idea to buy a copy of "Sky News" and get an 
approved set of eclipse glasses or get a set from any astronomy store or 
from our club.

-- 
    Clear Skies!
                MK

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