Ok, I managed to get one of these filters for the C8.
Tried it out today….
Very poor results!
I need to double check the collimation of the C8 just to make sure it’s not contributing to the issue.( I’ll probably temporarily mount the filter on the SW120mm which I know, with the Baader wedge gives excellent results)
Visually, it didn’t want to come to focus and the image was soft and lacked significant detail. Not impressed!
The filter seems to be made from two (??) layers - a shiny heavy reflective front layer and a dark rear layer which results in an orange solar image.
The President of the supplier of the filter material American Paper Optics says his business is 3D and Eclipse glasses and that he doesn’t know about the suitability of his filters to telescopes!!!!
I’ve sent emails to Celestron to ask for further technical details of this filter - transmission curves and surface quality- 1/10 or 1/4 wave or what?
In fairness I will retest this filter with the SW120.
Stay tuned.