RedCat 61 WIFD f/4.9 Petzval APORedCat 61 WIFD Designed from the ground up with the ability to handle the newest generation of large, heavy, high resolution cooled cameras, the rock solid optical tube assembly is uncompromised in quality. The movement of the focuser is integrated inside the main tube assembly, so there are no movements of a focuser drawtube visible from the outside. Enjoy the benefits of a traditional two speed fine focuser, while not worrying about limitations