The William Optics FLAT68III Adjustable Flattener is a correcting lens that will produce a flat focal plane across a large sensor. It is adjustable and as a result will suit many William Optics refractors, as well as any refractor with a 92mm threaded focuser and a focal ratio between 6 and 7.5.

The standard version of the FLAT68III is supplied with a short 48mm camera adapter. This will suit most refractors, but:

• if you are using a Gran Turismo 80 WIFD refractor, you will need an additional adapter, WO-AD-M80-54-M48 set at 2mm.
• if you are using a Fluorostar 91 refractor, you will need an additional adapter, WO-AD-M80-45-M48 set at 5mm.