Lens Packages By Neil Blevins Created On: Aug 1st 2014 Software: Any
When doing a live action film shoot, you buy or rent your
camera (usually rent), and then you choose a set of lenses that you
intend to shoot on. This set is usually referred to as a "Lens Package"
(I've also heard it referred to as a "Lens Kit"). While you could
potentially use an unlimited number of lenses, in general, you'll find
a Director or Director of Photography will tend to favor a small subset
of lenses, in some cases, and entire film might be shot using only 3-4
lenses.
How does this affect us in CG? Well, in CG, you can change your lens to
whatever you want. This gives you great power, but it also can break
consistency. Like in live action, maybe every time there's a closeup on
a character, the director chooses their goto 35mm lens. In CG, every
closeup might have a completely different focal length, which means
your character starts to look weird because every shot their face is
distorted in a slightly different way. So I highly recommend, if you're
doing a CG film, to make yourself a lens package, a small set of lenses
you'll be using for your virtual shoot. It will not only guarantee more
consistency (like how many films color grade a sequence to have a
consistent color scheme), but it will also more closely emulate the way
a real live action shoot is done. So if you're trying to emulate a live
action feel, best to emulate some of their techniques as well, and give
your virtual camera the same constraints the live action camera has.
Lets talk about a simple lens package, which might consist of a wide
angle lens (lets say 35mm), a telephoto (lets say 100mm), and a 50mm,
which is approx the same as what the human eye sees. Wide Angle lenses
tend to distort your subject, bulging things close to camera, and there
tends to be more apparent distance between your foreground and
background objects. Telephoto lenses tend to flatten out space,
decreasing the apparent distance between foreground and background
objects. But more on this topic in a different tutorial. From the
perspective of Lens Packages, having at least these 3 types of lenses
would let you achieve a number of different types of shots and stay
very consistent.
If you want to bring things to the next level and use a more
reality accurate camera in cg, different lenses also tend to have
different apertures which is marked in f-stops. So a specific lens
may only allow for a limited number of f-stops. The aperture controls
how much light enters the camera (so how bright the image will be) as
well as the depth of field (how blurry the background is). Again, more
detailed discussion of aperture should probably have its own tutorial
since its a complex topic. But for a true lens package, you should
limit yourself not just to specific focal lengths but each focal length
should be limited in terms of aperture. You can find this information
out by looking up real world lenses and see what sort of aperture they
tend to have.
For extra bonus points, each lens would also have a specific
distortion, for example, wide angle lenses tend to have some degree of
barrel distortion, and some telephoto lenses tend to have pincushion
distortion. But not all cg cameras allow you to modify the distortion
on the lens.
Talking to some experts, I found out that many of my favorite films
from the late 70s, early 80s were shot on Panavision cameras. For
example, The Empire Strikes Back and Indiana Jones And The Temple Of
Doom was shot on Panavision C Series Anamorphic Lenses. A little more
research shows that this lens package used for these films included:
These are all fixed lenses (Prime
Lenses) BTW, which means they only have one focal length each. You can
of
course throw a zoom lens into the mix, which will give you multiple
focal lengths, like say a 36-82mm lens. Although many films from that
era didn't use zooms, and used Fixed Lenses only. For at least some
info on what your favorite films were shot with (although lens focal
lengths are not included), feel free to check out http://shotonwhat.com/.
The standard 3dsmax camera actually has a lens package built in to the
tool, see below...
So you have a preset number of lenses, or you can adjust the focal
length above to be whatever you want. I wish there was a simple way to
customize this lens package, as it would make things way easier.
Knowing what lens package was used on a film can also help you if
you're a VFX person. Knowing what lenses were used for what shots makes
it far easier to replicate these real world cameras in the virtual
world (which is the process of matchmoving). And if you're adding some
full CG shots to the film, it's best to stick with similar lenses to
the ones used for the live action shoot, to help blend your completely
virtual shots with the practical shots.
So next time you're doing a short CG film, and you've done a little
research into wide angle and telephoto lenses, and in what situation to
use them, consider going one step further and make yourself a 5-10 lens
"package" of specific focal lengths, and stick to using those lenses
for your virtual shoot, only deviating if absolutely necessary. Or to
go one step further, have each lens have a specific focal length,
specific aperture range, and a specific type of lens distortion.
Unless of course the goal is to make something not of this world, in
which case all bets are off :)
