Filter questions

[Bastelhannes]

Hi folks,

playing with my SolEx Spectroheilograph and different telescopes (Skywatcher Startravel 102, Skywatcher Skymax 127, TS-Apo 70 f/6) I am thinking about filters to rpevent too much energy getting into the scope.

For the TS-Apo i tried using the Astrosolar foil with OD3.8, which is fun, but I need to increase gain too much to get nice pictures.
For the Skywatcher scopes I am using some DERF from Baader, but they of course are only useful for h-alpha.

Does anyone know a solution to use to get all wavelengths and lets enough light into the scope to obtain short exposures?

Ragards,

Karsten

[rsfoto]

Hi,

Just an idea try to use a Neutral Density filter but what about the produced heat in the SolEx ?

https://tinyurl.com/ND-Filter

[christian viladrich]

Hi Karten,
As far as I know, Christian Buil recommends using a solar wedge (Lunt or others).

[Bastelhannes]

Hi RS, hi Christian,

Thank you for your recommendations.

Christian Buil recommends a Herschel or solar wedge. I am just afraid to let so much sun into my telescopes.It is a lot of energy getting into the optical tubes.

ND filters seem to be a good solution (Thank you for the link). I am going to investigate some practical solutions.

[christian viladrich]

Hello Kartsen,
There is no problem at all with solar wedges.
I use one with my 150 mm f/7 refractor, and we have even use one (still specially designed) with a 435 mm f/15 refractor.

There is zero risk for the objective, and no problem at all for the "inside" of the optical tube as long at the light beam does not touch the easy of the tube. This is not a problem as long as you have a motorized mount. Air is not heating up inside the OTA since air is baiscally transparent.

This being said, Christian Buil also gives at alternate solution which is the use of a Hoya ND filter at the aperture of the telescope. See "partie 5"

http://www.astrosurf.com/solex/sol-ex-observation.html

[christian viladrich]

BTW, there is a group.io list for Sol'Ex. People there share information on Sol'Ex (software, procedure, mechanics, stl files, etc.).

It is both French and English speaking.

[Bastelhannes]

Thank you Christian,

Today I got to the conclusion to abandon my idea of using my C8 with the Sol'Ex. The turbulences at my obrservation place are too much. I will downsize to a aperture of 100 mm, everythign above that will increase resolution, but the turbulences destroy the image. Stacking is not possible.