Idea for an occulting disc?

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justanotherpete
Posts: 173
Joined: 07 Sep 2007, 20:24
Location: Rosyth

Idea for an occulting disc?

Postby justanotherpete » 22 Aug 2009, 12:41

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):

http://www.rothervalleyoptics.co.uk/baa ... _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?
Thanks
Pete

astrogeorge
Posts: 126
Joined: 25 Oct 2007, 10:06
Location: Kirkcaldy
Contact:

Postby astrogeorge » 23 Aug 2009, 21:50

Hi,
    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.
Celestron C100ED-R, Meade LX200 10" &  Series 5000 80mm Apo, Coronado PST
EQ6 Pro with GPS
Meade Series 4000 Eyepieces  & 2x Apo Barlow
Tele Vue 4x & 5x Power Mate
Meade DSI Colour & DSI II Pro, Image Source DBK 21, Canon Eos 400D

Cosmic
Posts: 364
Joined: 12 Jun 2008, 11:39
Location: Dunfermline
Contact:

Postby Cosmic » 24 Aug 2009, 17:21

Pete
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
Cosmic
Meade 8inch  SCT. Observatory mounted on an HEQ5 Pro using EQMOD Canon 1000D modified DSLR,200mm Dobsonian, 200mm Celestron C8, 15x70 Astro Binoculars. 2x Mintron ccd cameras, lots of other stuff.

justanotherpete
Posts: 173
Joined: 07 Sep 2007, 20:24
Location: Rosyth

Postby justanotherpete » 29 Aug 2009, 08:57

Thanks for the suggestion George - I'll look into that :)

Solar B
Posts: 162
Joined: 07 Dec 2006, 23:00
Location: Dalgety Bay

Postby Solar B » 29 Aug 2009, 14:43

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.

                                                                                     

                                                                                     
                                                                                Brian
" Gentlemen only ever use Refractors "


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