2-part-filter for solar filter film, for medium refractors like Skywatcher ED100 or TS CF-90 Apo and similar, telescopes. Maximum Lenshood-/Dewcap-diameter is about 125mm. Heat-thread-inserts (M5) are needed for the base-part (to fix the base to the dewcap) and M4 countersunk screws, nuts and washers for connecting the two top-parts and the filter

The filter system is made of two main parts:

1.) Base-part: connection to telescope

2.) Filter-top: (two filter top rings) between two top parts the filter film will be attached

Base and Filter part are connected via magnets. I use magnets with 5 or 6mm diameter and max. 2mm height (take a look to the pictures below).

Advantage with the magnets: During a total solar eclipse, when the totality has been started, you can easily remove the filter to make pictures of the visible corona and prominences. And you can easily fit the filter in front of the telescope again.

In addition, for all the "non solar eclipse days" you can use the magnet holder system to provide a filter top with e.g. ND5.0foil for watching and ND3.0 foil for photography.

The base part can be attached, fixed and centered on the telescope lens hood with three M5 screws, through "Ruthex" threaded inserts.
I painted the top part looking towards the sun in white color, to reduce heat-up process and therefore to minimize thermal elongation.

Attention: Never watch the sun without a filter made for that like Baader solar filter foil!!!

Check the solar filter for damage before each use!

If you don't know what to do exactly, ask a local amateur astronomer or person with knowledge about that!

Additional Info for a filter storage and for a save transport:
You can use any round shaped plastic box where you normally store 1,75mm 1kg filament spools. I'm using a simple 3.3 litre round shaped box.