ZWO 131mm Quad APO Refractor Maksutov DSO imaging cannot live without

DSO imaging cannot live without long exposure

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

which includes the B1800 blocking filter

Mother’s Day or just-because gift

but slightly to either side

ZWO 131mm Quad APO Refractor Maksutov DSO imaging cannot live withoutZWO 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