Re: ATM :Filters

["B. Pepin" <atmjedit@conceptsnet.com>]

Hi Ulhas,

This sounds like an interesting experiment, but a friendly warning: This
filter sounds UNSAFE to use alone for solar viewing, unless you are
projecting the image through the filter onto a screen, and viewing it that
way. It probably will let through considerable heat and ultraviolet
radiation. Also, a single coated glass filter of this type will not have a
narrow enough bandpass to block transmitted light around the absorption line
you want to "see through" to bring out H-alpha features, but it will
increase the contrast of solar features to some extent, possibly intensify
limb-darkening, etc., especially with photography and black-and-white film.

----- Original Message -----
From: Ulhas Deshpande <ulhas@nagpur.dot.net.in>
To: ATM <atm@shore.net>
Sent: Thursday, September 28, 2000 11:55 PM
Subject: ATM :Filters


>
> Hello All
> Where can i find out the characteristics, Center lambda ,transmission vs
> lambda,etc for various filters.When we talk of Nebula filter or H alpha
> filter what are the parameters one is looking for?
> I have found a glass filter which is centered at 652 nm and the
transmission
> drops to15% at  8nm each side. Can this be used to view the sun at H
alpha?
> Will it require additional filtering to reduce the transmission? Like
using
> it with the mylar solar filter which I have? The mylar filter makes the
sun
> yellow and the glass filter is red.
> The skies are now quite clear with the Cygnus bright overhead. I am hoping
> to finish figuring my Cass mirror in another week so I can star test it
and
> send it for aluminising.
> Wishing you all clear skies
> Ulhas
>
>