Astrograph 135mm D-ERF Custom Cell to fit 167mm 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 167mm diameter. Typically this means it will fit all OTA's produced by United Optics for 125mm Optics.

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 recommended for use with the Tecnosky 125mm ED Doublet Refractor (and also the TS Optics 125mm Doublet and Altair 125 EDF). When used with this as a solar telescope the focal ratio becomes F31.2 (using a Baader TZ-4) and F33.54 (using a Quark).