Shooting and Matchmoving
I'd like to talk with my
colleagues in the visual effects and cinematographer
fields about the pluses and minuses of shooting visual
effects with anamorphic lenses, as opposed to spherical lenses.
From the development of
Cinemascope in 1953, through the later widespread use of
Panavision lenses, anamorphic has long been the preferred 35mm
filming format of big feature films. But that started to change
when Silverado was shot in Super
35 spherical in 1985. And then director James Cameron pushed the
industry back into the common use of Super 35 spherical, with True Lies andTitanic, as well as
with the Ron Howard Super 35 production of Apollo 13.
The reason that Cameron
championed Super 35 spherical is that anamorphic lenses have
many problematic aberrations, which make them difficult to use
for visual effects, That's why the original Star Wars 4 visual
effects were shot on spherical Vistavision, since anamorphic
photography is quite counter productive for vfx.
So life was good for a
while, in the vfx heaven of spherical 35mm photography.
But since 2010,
anamorphic has been making a resurgence, especially sinceJohn Carter of Mars.
And in the digital age of Alexa and Red high end production
cameras, anamorphic photography has seen a rebirth.
And this resurgence is
perhaps not a good thing.
This is because, from a
Matchmove perspective, anamorphic sucks.
We have been working
closely with 3D Equalizer for the last two years, who have
developed sophisticated tools to handle the asymmetrical lens breathing of
anamorphic lenses. We know that spherical lenses exhibit a
slight focal length zooming during focusing, which is commonly
called "lens breathing". It is easy for us to solve for animated
symmetrical lens breathing in spherical. But anamorphic lenses
breathe differently in
the vertical and horizontal. So this asymmetrical anamorphic
lens breathing is quite a headache to track, even with the
excellent new anamorphic lens distortion models from 3D
Equalizer. It is common for a spherical shot to be tracked in
half the time as an identical anamorphic plate shot.
I recently was a
Matchmove supervisor on a major Hollywood action film, which was
shot with Alexa XT anamorphic, Alexa XT spherical and Alexa 65
non-trivial for an visual effects professional or audience
member to discern the difference between Alexa anamorphic
and Alexa spherical. But anamorphic is quite painful to track,
so what is the point of using that format, instead of
tried and true spherical? Of course anamorphic has
theoretical advantages, such as higher pixel count, weird lens
flares, softer images, heavy barrel distortion and
distinctive asymmetrical rack focuses.
Many current Alexa
anamorphic productions are actually using Panavision C lenses,
which are from the 1960s. These lenses are not very sharp, but
they are much more compact than more "modern" anamorphic lenses,
which are often bulky and heavy.
As a side note, the Alexa
65 footage on this same show was difficult to track, since it
was almost all underexposed and quite grainy. We had many shots
on the exact same sound stage set and because it was lit for
T/2.8 and the larger format Alexa 65 lenses only open up to T/4.
So even though the Alexa 65 is a 6K camera, an underexposed 6k
image looks much worse and is more difficult to track than a
plain vanilla Alexa XT spherical properly exposed.
currently capture can be 6k and exhibition in theaters is 4k
max, I think a director wishing to have an Anamorphic Release
should capture at the highest Spherical resolution that is
practical given the time, budget and local, 6k or higher if
possible. Then after all VFX work is complete, all the
Anamorphic artifacts and quirks can be applied digitally in
post like a DI session. Gate size must be chosen to be sure
through post there is always enough image captured to cover
for the needs of anamorphosizing in post. Since Anamorphic is
a less perfect result, we can digitally degrade any footage to
have the anamorphic signature attributes, but let's capture
the sharpest, best exposed, highest resolution flat image
like to open this subject up for discussion. I want to be
completely clear that in Matchmove departments around the
globe, when anamorphic plates are ingested into a Matchmove
department to track, there is a collective groan among the
cropped to 2.40:1
|Alexa anamorphic 4:3
|Alexa spherical 16:9
|Alexa Open Gate spherical
|Alexa 65 Open Gate
-Michael Karp, SOC
Arri ProRes is intended as an Alexa upscale to 4k UD
format. Details here.
It would seem from this chart that if you shoot Alexa Open
Gate spherical, the pixel count for 2.40:1 is almost as high
as anamorphic (4,8 million pixels, versus 5.6 million pixels).
Plus the spherical lenses are much sharper.