Focus mechanism in anamorphic lenses with counter-rotating cylindrical elements eliminating horizontal breathing during focus pulls.
The Rotating Astigmatizer is a focusing principle for anamorphic lenses, developed in 1954 by Robert Gottschalk for Panavision. Two cylindrical glass elements—the astigmatizers—rotate counter to each other during focusing, while the spherical main group is shifted linearly.
The Problem it Solves
Simpler anamorphic lenses focus using a variable front diopter: a movable lens in front of the main lens. This works but has side effects—chromatic aberration increases, the minimum focus distance remains far, and the image expands horizontally during focus pull (mumps effect). The Rotating Astigmatizer avoids this: the horizontal image axis remains stable, only the vertical axis changes minimally.
Who Uses It
Panavision used the Rotating Astigmatizer in almost all of their anamorphic lenses—C-Series, E-Series, T-Series, Ultra Panatar. For a long time, it was an exclusive Panavision technology. Xelmus from Ukraine incorporated the principle into their Apollo series starting in 2019, making it accessible as a purchasable lens for the first time. The design allows for minimum focus distances of 38 cm—exceptional for anamorphic lenses.
In Comparison
Variable Front Diopter: cheaper to manufacture, more chromatic aberrations, further minimum focus. Rotating Astigmatizer: more complex, fewer aberrations, closer focus, no horizontal breathing. Rear anamorphic designs (like ARRI Master Anamorphic) circumvent the problem differently—they place the cylindrical elements behind the spherical group.