American Cinematographer - May 2023 - 22

Optics Spotlight | Forming Glass
Jess Hall, ASC, BSC acknowledges he " had a pretty hefty list of requirements
for Chevalier in terms of lenses " - and to meet them, Panavision's
Dan Sasaki devised an experimental set of T0.9-1.4 primes.
Dubbed the " Ultra High Speed Primes, " the lenses offer " a bit more of
a vintage style, with softer contrast to give the feeling of deeper depth
of field, even at incredibly fast stops, " Sasaki describes.
" One of the problems with larger-format and fast lenses is that
depth of field becomes so shallow that it often becomes an image that
is difficult to manage, " Sasaki notes. " But depth of field is a perception
- it's about what the eye sees and the brain determines is in focus
relative to the information in a scene. If you have a super-sharp, contrasty
lens, then it's very easy to determine what is or isn't in focus and
the depth of field appears to be less. But, if you have a softer-contrast
lens, where the slope of the MTF is more gradual and occupies
a greater volume under the curve, the apparent difference of what is
in focus and what is out of focus appears to be less abrupt, giving the
impression of greater depth of field. "
In the attempt to produce the illusion of greater depth with such
a high-speed lens, Sasaki also manipulated the plane of focus (aka
Petzval or field curvature), making the edges of the image focus
behind the central object - the opposite of most lenses - and the
falloff more closely follow the curvature of the human face. (Editor's
note: The field of focus in a normal lens is a flat plane - parallel to the
film plane. But in a " natural " or uncorrected lens, this field is curved
forward so the center of the lens focuses farther away than the edges,
and an optical designer has to force the edges to focus farther away
so the plane is flat. In the case of Chevalier, Sasaki forced this plane
to focus backward - away from the focus plane - so that the center
would focus closer than the edges. This means that instead of just the
tip of an actor's nose being in sharp focus and everything else falling
away, the plane of focus would form an ellipse that more closely followed
a face. As a result, the area of faces that includes the nose and
cheeks becomes more focused, making it appear that those images
have more depth of field.)
" These lenses are never mathematically sharp, " Hall says, " but we
were aiming for a more ethereal sharpness, where the falloff isn't as
extreme and you effectively get more perceived depth of field. "
The markings on two of the show's Panavision Ultra High Speed
Prime lenses, highlighted by Hall.
The cinematographer also wanted the lenses to replicate the
warm halation of the candlelit scenes in Barry Lyndon, and Sasaki's
efforts to achieve this led to a happy accident. " We really studied
those images to look at the lenses' aberrations, " Sasaki recalls.
" While incorporating those aberrations into these new lenses,
I actually made a big mistake. We had limited time to make the
modifications, so we based the results on a lens projector. A couple
of days before production, I got the look we'd discussed and was
really excited to show Jess, and then I suddenly remembered that
lens projection shows the opposite effect of aberrations! So, the
warm halation I'd built into the lens actually became a blue/violet
halation from photographed light. It was really lucky that Jess loved
the effect. It added an additional, natural color separation to the
highlights - but it was a mistake! "
Says Hall, " It was a mistake that parlayed into a unique look and
became quite special. I fell in love with it. "
Sasaki describes the UHS primes as " an experimental set of
lenses that were inspired by Barry Lyndon and Jess Hall's love for
vintage optics. They were also built to share some of the imaging
characteristics of our new VA primes. Since the initial designs
were capable of covering a 65mm sensor, we were able to reduce
the diagonal and pick up some speed with a custom image circle
reducer, which allowed us to produce lenses capable of an f/0.9 to
f/1.4. This was a hugely experimental endeavor, and if it weren't for
Jess' inspiration and patience, this project would not have taken off
as well as it did. "
Hall notes, " The markings on our set - 0.9-1.4 - matched
exactly what I found in testing and shooting, in relation to my
light-meter readings - which were confirmed via waveform and
precise monitoring. For example, when moving from the 50mm T0.9
to the 40mm T1.2, I had to raise the light levels by approximately
half a stop. Changing focal length from the 50mm T0.9 to the
75mm T1 also required more light, and so on.
" Dan and I have this ongoing collaboration, " the cinematographer
adds. " He brings something I can't always bring, and we meet on
very fertile ground. "
- Jay Holben
22 / MAY 2023
American Cinematographer - May 2023

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