ZWO 131mm Quad APO Refractor Maksutov Celestron engineers drew on their

Celestron engineers drew on their decades of expertise while designing every detail

but slightly to either side

6 Tele Vue Parfocal Group B* Use with Bino Viewer Y DIOPTRX Compatible Y FoneMate Compatible Y Field Stop (mm) 8

The mechanical design of the Askar 91F itself adheres to Askar's consistent philosophy of taking into account the user's habits and minimizing the user's invisible costs

ZWO 131mm Quad APO Refractor Maksutov Celestron engineers drew on theirZWO FF131 APO Flat Field Apochromatic Refractor *Focus can be achieved within a back focus range of 4273 mm, measured from the M54M48 interface shoulder. Main Features Flexible Connectivity for Multiple Configurations Uniqueness Four Element Optical Design The FF131 APO features a four element, fully air spaced apochromatic optical design. All four elements work together to deliver a flat imaging field without the need for an additional field