Focus Scientific

William Optics FLAT61A Adjustable Flattener for Z61 APO Refractors

A curved focal surface is an inherent feature in most telescope designs. While this of no great consequence for general visual observation, for astrophotographers the consequences of that same curvature of field is a softening of focus in the outer parts of the frame. Designed for both the Z61 and Z73 APO refractor, the Flat61 Field Flattener does what its name implies; it flattens a curved focal surface so that it closely enough conforms to the flat plane of a camera sensor.

The Flat61 threads directly into the focuser, after un-threading the 2" accessory adapter. It requires a 48mm 'wide' T-adapter, available extra for Nikon, Canon and Sony cameras. Depending on the telescope objective characteristics, and if compatible, the flattener is adjusted for the optimal sensor placement, in the manner of a focusing camera lens. The extending barrel is calibrated in millimeters; simply turn the ring until the desired degree of extension is read off the printed scale, then lock it down.

Weight: 0.27kg (0.6 lbs)