How were early CinemaScope anamorphic lenses designed, and how did later anamorphic systems differ?
Asked 10/24/2025
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I’m trying to understand the optical design of early anamorphic cinematography systems such as CinemaScope. From what I’ve read, the earliest setups used an anamorphic attachment on the camera and a complementary attachment on the projector, rather than a fully integrated taking lens.
Am I basically correct about that? More specifically:
- Were these early anamorphic attachments essentially cylindrical lens elements that compressed or expanded the image in only one axis?
- Are there good references or ray-trace diagrams that explain how anamorphic optics are laid out?
- Did later anamorphic designs change substantially, for example by integrating the anamorphic group into the lens rather than using a front attachment, or by using different optical forms?
Originally by uhoh. Source · Licensed CC BY-SA 4.0
uhoh
7mo ago
2 Answers
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I haven't seen many ray traces, probably because they look basically the same for an anamorphic lens. It's just that they look slightly different in the vertical and horizontal axis (diagram of anamorphic lens element traces from pencil of rays website)
It might be best to think of the add on lenses as simple diopter elements; except that they only have a magnification in the vertical axis. They are always combined with spherical/aspherical elements for the image formation. The add-on camera lens element is a front anamorphic element, and the projector element is a rear anamorphic to correct the distortion; you can also have middle anamorphic elements. And there are positive (vertical stretching) and negative (horizontal compressing) aspheric elements; both give the same basic effect (used individually).
The thing to take from the above ray trace is that the vertical and horizontal nodal points are different. And that difference is called the anamorphic distance. This is a 3D image formation affect that cannot be corrected in 2D. I.e. an image that is compressed horizontally during recording can only be corrected by stretching for display/projection at the focal plane (E.g. elliptical bokeh).
Anamorphic elements can be circular in cross section, but they do not need to be. Front anamorphic elements often were/are some form of rectilinear in shape like this freewell adapter. Sometimes the rectilinear shape is just a mask, and sometimes it doesn't exist at all (internal/rear elements).
Originally by Steven Kersting. Source · Licensed CC BY-SA 4.0
Steven Kersting
7mo ago
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Generated from our catalog & community — verify before relying on it.
Yes—at a high level, early CinemaScope-style systems used anamorphic attachments with the taking lens on the camera and a complementary element on the projector. The anamorphic part changes magnification in one axis only, while the rest of the lens forms the image.
The key idea is cylindrical/anamorphic power: the lens focuses or magnifies differently horizontally and vertically. So instead of behaving like an ordinary spherical element that brings rays to a point, an anamorphic element effectively acts in one direction only. That’s why anamorphic optics are often described as having different behavior on the two axes, and why ray diagrams look similar to normal lenses except that horizontal and vertical sections differ.
Later systems did evolve beyond simple front attachments. Anamorphic groups can be placed at the front, middle, or rear of a lens design, and the image-forming optics are typically combined with spherical or aspherical elements. In practical terms, later anamorphic lenses are often more integrated designs rather than just add-on attachments.
If you look for ray traces, search specifically for cylindrical/anamorphic lens ray diagrams; they’re usually shown as separate horizontal and vertical optical sections.
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