The William Optics RedCat 51-II-U APO is a 250mm prime lens suited to a DSLR or astrocam. The 4-element Petzval lens arrangement will ensure a flat image plane, meaning no flattener is required and your stars will be sharp to the edge of the field.

The latest version of the RedCat 51 has a concealed tilt adapter, which you can use to correct any tilt in the imaging train.

Fields of view for the RedCat 51 will depend on your camera’s sensor size. For example, an APS-C size frame will give a field of view of approximately 5.4° x 3.6°. A full frame camera will give a field of view of 8.25° x 5.5°.