The Rank-Taylor-Hobson Zoom Lens

By far, this was the most popular zoom for RCA TK41s and TK60s. The Zoomar was also very popular, but that was seen mostly on black and white cameras in use prior to the mid 60’s introduction of this lens. This is often refereed to as the Varotal III and Varotal V. The Mark V model is for studio use and the Mark III for outside.

Varotal Lenses (From the RCA Product Catalog)

The Studio Varotal V and Outdoor Varotal III are variable focal length lenses designed to cover the full range of focal lengths normally used for television programming. By eliminating the need to switch to a second camera for change of lens turret position, the Varotals provide means of producing a variation of close-u p and distance “shots” with only one camera. The lenses enable observation of detailed processes without the loss of continuity entailed in changing lenses. In addition, dramatic effects may be obtained by “zooming” from a distance shot to a close-up of one portion of the scene, or from a close-up view to a distance shot.

Outdoor Varotal III

The Outdoor Varotal III Lens has been designed for versatile use in studios or on remotes. It features a unique dual range change from 4 to 20 inches and from 8 to 40 inches by means of a small lever on the lens without change of rear element or loss of picture focus. High quality definition is achieved and the lens is fully color corrected and designed for use on both color or monochrome cameras. Minimum object distance for which the entire zoom range is available is twelve feet, and a close-up adaptor is available for reducing the minimum object distance to six feet.

The zoom and focus controls for the Varotal III are combined in a lever mechanism which mounts on a bracket attached to’ the rear of the camera. The controls are mechanically coupled to’ the lens by means of a pair of flexible cables and a precision gearbox which is mounted on the lens. Zoom control is provided by rotation of the lever.

Focus control is provided by rotation of a knob mounted an the zoom control lever. The direction of rotation of the focus knob, with respect to focusing action, corresponds to that of the regular camera focus knob, for ease and familiarity of operation.

An adjustable friction brake is provided to vary the amount of pressure required to operate the zoom control in accordance with individual operator preference. This brake may also be used to lock the zoom control at any desired point within the zoom range.

Varotal V

The Varotal V is a new Zoom lens with a focal length range of 1.6 to 16 inches and a relative aperture of f/4.0 to f/22.0 throughout the zoom range. The focal length and optical speed of this lens make it suitable for both studio and outside broadcast use. The linear iris mechanism conforms to all requirements for adjustment by an iris motor drive system or manual operation.

The separate zoom and focus control of the lens are mechanically coupled to the lens by two separate flexible cables. The zoom mechanism is mounted on a bracket at the right rear of the camera, and a lever on this control adjusts the focal length of the lens. A knob is attached to this lever for adjustment of zoom friction and may be used to lock the iris at any point within the zoom range.

The zoom mechanism is a dual speed device which has two output couplings permitting a choice of zoom speeds by attaching the control cable to the desired output coupling. The focus control handle is attached to the camera pan and tilt head handle at left rear of the camera and is coupled to’ the lens by a flexible cable. The Varotal V lens requires a field lens when used on a TK4I Color Camera.

Three range extenders and a close-up adaptor are available as accessories for the Varotal V. The extenders change the range of the basic lens to 2.4 to 24 inches, f/6.0; 3.2 to 32 inches, f/8.0; and 4.8 to 48 inches, f/12.0. The close-up adaptor has a minimum object distance of three feet.

The Varotal III and V are mounted on the RCA TK-11, 31 and TK-l4 monochrome TV Cameras by means of a special mounting plate which is readily installed in place of the standard camera turret. Either lens may be mounted directly on the TK-60 camera turret. Control cables and a suitable mounting bracket for the zoom and focus control mechanism are supplied with the lens. Ordering information should specify the type of RCA camera on which the lens is to be mounted.

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