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Idea for an occulting disc?

Posted: 22 Aug 2009, 12:41
by justanotherpete
Was trying to think of a way to reduce the brightness of the solar disc in my PST to make prominences etc at the limb stand out more and came up with this:

Take one of these filters (nearest I could find to plain glass): ... _d499.html

Then attach to it centrally a small circle of black card / paper / insulating tape that's approximately or slightly less than the diameter of the sun's image in the eyepiece (probably some trial and error would be needed here).

Then viola! An occulting disc filter that screws into the eyepiece you are using with your PST; most of the sun is obscured except for the limb so perhaps prominences would be more visible?

Just wondered if anyone had any thoughts on whether this might work?

Posted: 23 Aug 2009, 21:50
by astrogeorge
    As far as I'm aware using colour filters with your pst makes no difference. There for i would just buy something like the meade moon filter.

Posted: 24 Aug 2009, 17:21
by Cosmic
All i know about black spots is what I read in Treasure Island :)
however seems like a goer so why not try it and report back to us.
Bests of luck

Posted: 29 Aug 2009, 08:57
by justanotherpete
Thanks for the suggestion George - I'll look into that :)

Posted: 29 Aug 2009, 14:43
by Solar B
Hi Pete

            You should be able to De-tune the Etalon away from surface
            detail and towards Limb,i have used variable Pol filters
            in the past with PSTs which do improve contrast a bit on
            the surface,for ulitimate PST views a Double stack filter
            is required,this is great for surface and limb,proms can take
            on more of a 3D affect.