The Hiltner 2.4-meter telescope (named after W. A. Hiltner, 1914-1991) is a fork-mounted equatorial telescope which is close to, but not quite, a Ritchey-Chretien design in its nominal f/7.5 focus. Behind the primary mirror is an instrument rotator, and behind that is usually mounted the Multiple Instrument System (MIS), which must be removed for use of the 8K CCD in order to open up the field of view.

FIELD OF VIEW

The principle cause of vignetting is associated with the central perforation of the primary itself, which consists of a 305 mm aperture sitting 899 mm in front of the f/7.5 focus, creating vignetting for image diameters greater than 182 mm, corresponding to 35 arcmin, just larger than the diagonal of the 8K array, 34 arcmin (or 24 arcmin on a side). The baffle behind the primary is somewhat over 11 inches in diameter, near the front surface of the primary (according to Bob Barr, 25 Nov. 1998), which would produce an unvignetted field diameter of about 6.3 inches, or 160 mm (31 arcmin). The uncorrected field suffers from focal surface curvature, astigmatism and some coma at large field angles.