Heya! Welcome back to the Anamorphic Cookbook! I’m Tito Ferradans
and this is the fourth chapter of Module 1. This module gives you a
good foundation of knowledge about the origins of anamorphic in film, how the lenses work,
why anamorphic is such a big deal and how you can use it to boost production value in your work.
If you missed the previous chapters, I highly recommend you check them out before moving forward
In this chapter I’m gonna talk about how anamorphic lenses do what they do,
and what sets them apart from regular, pedestrian, spherical lenses.
WTF IS A SPHERICAL LENS?
Spherical lenses get this name because the curvature for each of their elements is part
of the radius of a larger sphere. For example, here’s the cross section of a Helios 44.
These would be the spheres for each face of each element.
The difference in their size - radius! - is what controls how each element shapes the light.
In recent times aspheric elements have become more and more common,
but their effects are pretty much the same as spherical elements for the purposes of
our comparison. To learn more about aspherical elements, check the link in the description
The spherical shape ensures that light behaves the same in all directions. For example if one
of the elements causes the red beams to veer off-track increasingly towards the edges,
that’ll happen uniformly towards all edges in the image circle.
ANAMORPHIC PRISMS
The cornerstone for anamorphics on the other hand is distortion. Yes, a special and controlled
distortion, applied only in one axis. There are two main ways to create this distortion.
The first method, less popular these days is using prisms.
It was introduced in 1831 by Sir David Brewster in his Treatise in Optics.
He demonstrated it with a pair of similar refracting prisms, one with the apex (the
pointy part) to the right and the other one to the left. Changing the angle between them causes
the image to be compressed or expanded in a single axis, making for a controllable variable squeeze
wanamorphic system. This concept is actually the base for Panavision’s Super Panatars, which lived
in the same time period as Chrétien’s Hypergonars - both of these mentioned in the previous video.
The prism design is not as strong as Chrétien’s because the lenses get big
pretty quick, making them unwieldy in the field,
plus it is more difficult to achieve good chromatic aberration performance,
and field focus. Performance is asymmetrical when comparing both sides of theimage, since each side
of the picture is being compressed by one of the prisms. They’re great for projection because those
remain at a fixed focus distance, but not so great for the dynamic environment of filming.
ANAMORPHIC CYLINDERS
The second method for anamorphosis is the one used in the Hypergonars and the vast majority of other
anamorphics ‘til this day. The compression is created by cylindrical glass elements.
If you look at the drawings on Chrétien’s patent, you can see that if we expand this shape,
it doesn’t turn into a sphere, but a tube,
a cylinder, hence the name, cylindrical glass. Curvature exists only in one axis,
creating the squeeze. The wider the cylinder, the lesser the squeeze. So a lens with a wider
cylinder diameter has a more subtle compression than one with a narrower cylinder diameter.
A common issue that arises from this shape is compression tends to be uneven across the frame;
much more pronounced near the edges than in the center. If you look at the usual two-element
design featured in most projection lenses, like Kowas and Sankors, it’s easy to see that
as we approach the tangent of the cylinder. the thickness of the glass in the lens
increases dramatically. That correlates to the stronger compression and is rooted in
how the optics work - we’ll talk a bit more about it later on, in Module 2.
To make matters worse, the squeeze factor is only the advertised value at infinity focus,
becoming weaker and weaker as the elements approach one another for close focus.
For example, the original CinemaScope lens had a squeeze of 2.5x when focused farther than 30ft
and that went down to 1.8x when focused at 5ft.
TECHNICAL RECAP
We ran through a lot of concepts in this chapter so far, so here’s a short summary:
prisms can be used to squeeze an image and even create variable squeeze systems,
yet they disappeared over time because they don’t perform as well as cylinders.
We use cylindrical glass on anamorphics now, but the basic cylinder shape doesn’t hold a constant
squeeze across the frame and it also doesn’t hold constant squeeze over the focused distances.
These optical traits are what led to the whole mumps drama in Hollywood.
You put an actor in the center of the frame, they don’t look as thin as they do on the sides
of the frame. Then you push in close and now your talent definitely looks chubbier than real life,
with a rounder face - and this was at a time without a body-positive mentality.
Skinny is key - check the “Magic Portrait Filter” video in the resources after this chapter.
The original CinemaScope lens is a very flawed piece of equipment
being used as a key element in a multi-million dollar industry.
In the next module we’ll look at how some of these issues have been addressed over time,
but before we get to that we have to talk about aspect ratios and how that relates to anamorphic
pictures and their “je ne sais quoi”, what makes them so special to audiences and filmmakers.
But that’s next week. For now, use the comments below to shoot any questions
you have about the structure of these lenses and if you’re not a member,
remember that you can get these videos early by clicking the “Join” button right below the video!
It costs less than a coffee cup every month, and it gets you much more than just early access.
I hope you learned something cool here today, and I’ll see you next time. Tito Ferradans, out.