Astrograph 135mm D-ERF Custom Cell to fit 156mm Dew Shield

This is a custom made cell to take a Baader 135mm D-ERF Energy Rejection Filter. It is made to fit dew shields with a 156mm diameter. Typically this means it will fit an Astro Physics 130mm F6.3 Refractor. It may fit other OTA's sharing this dew shield size.

By acting as both an aperture stop and ERF, the cell permits a wider range of scopes to be converted for use with rear mounted H-Alpha filters for solar observing and imaging.

When fitted the 135mm D-ERF provides an aperture of 125mm.

This ERF cell is optimised for use with the Astro Physics 130mm F6.3 Starfire Refractor. When used with this as a solar telescope the focal ratio becomes F26.2 (using a Baader TZ-4) and F28.17 (using a Quark).