Internal Filter Holder for Askar SQA85

This internal filter holder is designed for the Askar SQA85 telescope. It allows for the installation of a filter with an M48F thread (for 2" filters) directly into the M76F-M48M adapter, eliminating the need for an additional filter drawer.

The holder securely clamps inside the adapter between the adapter and the telescope, facilitating easy filter installation. The holder extends the back focus by 0.5 mm, while the addition of a filter shortens it by approximately 0.8 mm, resulting in a total back focus "error" of about 1.3 mm, which is negligible for the Petzval design of the SQA series.

This model is also compatible with other refractors in the SQA series that use the M76-M48 adapter ring. It is recommended to measure before installation for best fit. The model is printed in PETG, although black matte PLA could also be used to reduce reflections.