Astrograph 135mm D-ERF Custom Cell to fit 186mm 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 186mm diameter. Typically this means it will fit all OTA's produced by United Optics for 150 / 152mm 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. When fitted to the following OTA's the focal ratio will change as follows;

Tecnosky 152mm F5.9 Achromat (also fits TS-Optics 152mm F5.9, Altair Starwave 152 and others). Focal ratio becomes F7.17 (with TZ-4 this is F28.7, with Quark F30.85)

APM Telescopes 140mm F7 Doublet Apochromat. Focal Ratio becomes F7.84 (with TZ-4 this is F31.36, with Quark F33.71)

APM Telescopes 152mm F7.9 Doublet Apochromat. Focal Ratio becomes F9.6 (with TZ-3 this is F28.82)

​Tecnosky 152mm F7.9 Triplet Apochromat. (also TS-Optics 152mm ED Triplet and 150mm Doublet, Altair Wave 152mm ED Triplet and 150mm EDF Doublet). Focal Ratio becomes F9.6 (with TZ-3 this is F28.82)

APM-LZOS 152mm F7.9 Triplet Apochromat (Aluminium Tube). Focal Ratio becomes F9.6 (with TZ-3 this is F28.82)